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CCIE SP Written Concepts > CCIE SP Written > Flashcards

CCIE SP Written Flashcards

1
Q

ISIS LFA FRR?

A

Pre-computed Backup route.

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2
Q

ISIS LFA FRR when there is a primary path link failure?

A

The backup routes (repair paths) are precomputed and installed

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3
Q

Can ISIS LFA FRR be more than one hop away? For what purpose?

A

Yes. Commonly used in ring topology.

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4
Q

What other protocol needs to be supported in order to run ISIS LFA FRR?

A

MPLS-TE

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5
Q

ISIS LFA FRR IOS restrictions?

A
  • TE tunnel interface not protected
  • IPv4 multicast supported.
  • IS-IS LFA calculations restricted to same level or area.
  • Only physical interfaces and physical port-channel interfaces protected.
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6
Q

What is the LFA?

A

Alternate node other than primary neighbor.

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7
Q

What algorithm is used to compute per prefix LFA’s?

A

The general algorithms found in RFC 5286

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8
Q

Why does ISIS examine LFA prefixes after SPF is performed for each neighbor?

A

IS-IS retains the best repair path .

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9
Q

Can a primary path have multiple LFAs?

A

Yes, but requires routing protocol

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10
Q

What are the attributes used for tie-breaking in ISIS LFA FRR?

A
  • Downstream
  • Linecard-disjoint—
  • Shared Risk Link Group (SRLG)
  • Load-sharing
  • Lowest-repair-path-metric
  • Node protecting
  • Primary-path
  • Secondary-path
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11
Q

How is ISIS LFA FRR configured in IOS?

A

isis [area-tag] fast-reroute remote-lfa {level-1 | level-2 } mpls-ldp [maximum-metric metric-value]

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12
Q

How is ISIS LFA FRR configured in IOS-XR?

A

interface Bundle-Ether bundle-id

address-family {ipv4 | ipv6}

fast-reroute per-prefix

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13
Q

What are some differences between SONET and SDH?

A

SONET - USA and Canada, SDH is used everywhere else.

SONET header (IP or Ethernet) may be interleaved into the payload at layer 1. Pattern is repeated until entire packet is sent.

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14
Q

What is lais?

A

Line Alarm Indication Signal (If SLOF or SLOS, set at remote end)

Low level alarm used in SONET/SDH used for failure detection

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15
Q

What is pais?

A

Path Alarm Indication Signal (Defect noticed on peer signal; minor)

Low level alarm used in SONET/SDH used for failure detection -

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16
Q

What is prdi?

A

Path Remote Defect Indication (issue with a node two sites away)

Low level alarm used in SONET/SDH used for failure detection -

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17
Q

What is slof?

A

Section loss of frame (errors in the framing pattern/alignment)

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18
Q

What is slos?

A

Section loss of signal (0->1 or 1->0 bit transitions not seen

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19
Q

Can SONET keepalives be mismatched between pairs?

A

Yes. Timers can be mismatched, one side can have it enabled, the other can have it disabled.

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20
Q

POS interface default CRC?

Extra resiliency?

A

16/32

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21
Q

What is APS for SONET and what is it used for?

A

Automatic Protection Switching - Allows for a pair of SONET links to serve as active/standby.

The working (W) link is backed up by the protect (P) link failover time is about 50ms.

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22
Q

For SONET APS, can the links be in different APS groups? How do the routers communicate APS information?

A

No, must be in the same group. The routers use Protect group protocol (PGP) to send APS info.

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23
Q

What exists over SONET/SDH for OAM functionality?

A

A Data Communications Channel (DCC). Can also be used for remote provisioning.

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24
Q

List all the SONET OC levels/Frame formats/SDH level and frame formats/and Line Rate

A

OC-1/STS-1 (810 bytes)/STM-0/51.84Mbps

OC-3/STS-3/STM-1/155.52Mbps

OC-12/STS-12/STM-4/622.08Mbps

OC-24/STS-24/N/A/1.244Gbps

OC-48/STS-48/STM-16/2.488Gbps

OC-192/STS-192/STM-64/9.953.28Gbps

OC-768/STS-768/STM-256/39.813Gbps

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25
Q

What is the frame format for an OC? How many are in an OC-3?

A

STS-1. 3 STS-1s.

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26
Q

What is LTE?

A

Long Term Evolution architecture consists of many various components that make up Mobility

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27
Q

Under mobility, what is UE? What is an example?

A

User Equipment. End-user device like a cellphone.

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28
Q

What does each UE contain? What is another name for it? What does it do?

A

Universal Integrated Circuit Card (UICC).

Under LTE context, known as Subscriber Identity Module (SIM). Identifies a phone’s number, billing plan, and all other network-related information.

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29
Q

What is eNodeB?

A

eNB, are base stations that control the mobile nodes in one or more calls.

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30
Q

What is a serving eNB?

A

A base station that is supporting a specific mobile node.

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31
Q

How many base stations can LTE mobile nodes communicate with?

A

one.

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32
Q

What is UMTS?

A

Universal Mobile Telecommunications System.

3G network that 4G LTE was built on. Was a combination of packet and circuit switched architectures.

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33
Q

What is E-UTRAN?

A

Evolved UMTS Terrestrial RAN.

Encompasses entire LTE architecture.

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34
Q

What services does E-UTRAN cover?

A
  • Mobility control
  • Radio admission control
  • eNB configuration and provisioning
  • dynamic resource allocation (Scheduling)
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35
Q

Is E-UTRAN packet or circuit switched?

A

Designed to be Packet switched, all IP network.

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36
Q

What are the upload and download rates of E-UTRAN?

A

Download - 299.6 Mbps, Upload - 75.4 Mbps.

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37
Q

What are the standardized E-UTRAN cell widths?

A

1.4 MHz, 3, 5, 10, 15, and 20 MHz

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38
Q

What is EPC?

A

Evolved Packet Core - responsible for forwarding traffic, handover events, filtering, billing and accounting.

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39
Q

Within EPC, what is HSS?

A

Home subscriber service - A central database that contains info about all the subscribers within a given network

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40
Q

What is PDN?

A

Packet Data Network - Any external network outside of LTE, like the internet.

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41
Q

What is P-GW?

A

PDN gateway -

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42
Q

What is MAM?

A

Maximum Allocation Model - support enforcement of Bandwidth Constraints

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43
Q

Describe traffic types in Diffserv-TE

A
  • regular traffic
  • constraint-based routing of “guaranteed” traffic

which satisfies a more restrictive bandwidth constraint than that satisfied by CBR

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44
Q

What is the regular regular TE tunnel bandwidth called?

A

Regular traffic or Bc0

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45
Q

What is the more restrictive or “guaranteed” traffic pool called?

A

The more restrictive bandwidth is termed a sub-pool or Bc1

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46
Q

Why is the sub-pool important?

A
  • more restrictive bandwidth constraint
  • higher Quality of Service performance in terms of delay, jitter, or loss for the guaranteed traffic.
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47
Q

What are the two models of allocating constrained bandwidth? What do they achieve?

A

MAM and RDM. Bandwidth efficiency, isolation across Class Types, and Protects against QoS degradation.

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48
Q

When would you use MAM?

A

When there is a need to ensure isolation across all Class Types without having to use pre-emption

can afford to risk some QoS degradation of Class Types other than the Premium Class.

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49
Q

When would you use RDM?

A

Prevent QoS degradation of all Class Types and can impose pre-emption.

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50
Q

What are the benefits of DiffServ-aware Traffic Engineering?

A
  • Separate admission control and separate route computation for discrete subsets of traffic (for example, voice and data traffic).
  • Develop QoS services for end customers based on signaled rather than provisioned QoS
  • Build the higher-revenue generating “strict-commitment” QoS services, without over-provisioning
  • Offer virtual IP leased-line, Layer 2 service emulation, and point-to-point guaranteed bandwidth services including voice-trunking
  • Enjoy the scalability properties offered by MPLS.
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51
Q

What is DS-Lite?

A

The Dual Stack Lite (DS-Lite) feature enables legacy IPv4 hosts and server communication over both IPv4 and IPv6 networks.

Also, IPv4 hosts may need to access IPv4 internet over an IPv6 access network. The IPv4 hosts will have private addresses which need to have network address translation (NAT) completed before reaching the IPv4 internet.

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52
Q

What are two components of the Dual Stack Lite application?

A
  • Basic Bridging BroadBand Element (B4):
  • Address Family Transition Router(AFTR):
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53
Q

How does the DS-Lite feature help?

A
  • Tunnelling IPv4 packets from CE devices over IPv6 tunnels to the ISM blade.
  • Decapsulating the IPv4 packet and sending the decapsulated content to the IPv4 internet after completing network address translation.
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54
Q

What is GPON?

A

Ethernet or passive optical network (PON) technologies

GPON is a point-to-multi point access mechanism.

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55
Q

What are the primary features and benefits of GPON?

A

● Single fiber transceiver with single-mode SC receptacle

● Complies with ITU-T G.984.2 class B+ and C+

● Digital Optical Monitoring (DOM) support

● Complies with RoHS6 directive

● Point-to-multipoint

● Broadcast protocol uses TDMA

● High port density OLT at headend

● Low-cost ONT/ONU at home

● Primary market: FTTH for voice/data/video

● Low-cost passive optical splitter enables sharing of fiber, headend equipment

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56
Q

What protocol does RSVP-TE ride over?

A

IP Protocol 46

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57
Q

What label distribution method does RSVP use?

A

Downstream on demand

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58
Q

What is downstream on demand?

A

Downstream device doesn’t provide Label mapping until requested by an Upstream device

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59
Q

What is downstream unsolicited?

A

In this mode an LSR does not wait for a request from an upstream device before signaling FEC-to-label bindings. As soon as the LSR learns a route, it sends a binding for that route to all peer LSRs, both upstream and downstream. One disadvantage of this is that it doesn’t help in conserving labels as LSR receives label mappings from neighbors that may not be the next hop for the destination. This mode is used by BGP-LU and LDP.

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60
Q

What label control mode does RSVP use?

A

ordered control

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61
Q

What is ordered control?

A

n this approach, an LSR doesn’t advertise a FEC unless it’s the egress LSR for that FEC or until it has received a label for the FEC from its downstream peer. For each FEC for which the LSR is not the egress and no mapping exists, the LSR MUST wait until a label from a downstream LSR is received before mapping the FEC and passing corresponding labels to upstream LSRs. This is used by RSVP, LDP (JunOS) and BGP-LU.

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62
Q

What is Independent control?

A

This means that the LSR sending the label acts independently of its downstream peer. It does not wait for a label from the downstream LSR before it sends a label to its peers. This mode has the potential of blackholing the traffic. For instance, when operating in independent Downstream on Demand mode, an LSR may answer requests for label mappings immediately, without waiting for a label mapping from the next hop. This mode is used by LDP (IOS/IOS-XR)

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63
Q

What label retention mode does RSVP use?

A

Conservative Retention Mode

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64
Q

What is conservative retention mode?

A

In this mode LSR store only labels from a neighbor who is currently next hop for a FEC. The advantage is that it requires less memory

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65
Q

What is liberal retention mode?

A

In this mode LSR store all the labels received by the neighbors. One dis-advantage of this mode is that it requires more memory to store all the labels but provides faster convergence.

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66
Q

What is BFD?

A

Bidirectional Forwarding Detection (BFD) is a lightweight keepalive protocol design to reduce dead peer detection time across layer 2 networks. It is used primarily on networks that do not rely on line-protocol for interface status (like Ethernet).

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67
Q

What does BFD use for transport?

A

UDP, BFD uses echo messages to test reachability between neighbors and control messages for signaling.

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68
Q

Can other protocols register to BFD?

A

Yes, EIGRP, OSPFv2/3, IS-IS, BGP, RSVP-TE, PIM, and xconnect

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69
Q

Does BFD do neighbor detection?

A

NO. BFD does not perform neighbor detection; it relies on the registered protocol to do that, then runs probes based on those discovered IPv4/v6 neighbor addresses.

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70
Q

What is VRF lite?

A

Segment networks without MPLS.

Multiple routing tables that are completely separate from each other.

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71
Q

What is the purpose of a BGP confederation?

A

To achieve a full mesh of iBGP peering.

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72
Q

What is a route-reflector?

A

Routing information exchange server for all other iBGP routers.

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73
Q

What are the 4 message types used in BGP?

A

OPEN

UPDATE

NOTIFICATION

KEEPALIVE

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74
Q

Describe the BGP open message

A

Negotiate session capabilities

Contains:

BGP ver number

ASN of originating router

Hold time

BGP identifier

optional parameters

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75
Q

Describe the BGP update message

A

Advertises any feasible routes, withdraws previously advertised routes.

Includes the NLRI that includes the prefix and associated BGP PAs when advertising prefixes.

Withdrawn NLRIs include only the prefix.

An UPDATE message can act as a Keepalive to reduce unnecessary traffic.

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76
Q

Describe the BGP notification message

A

Sent when an error is detected with the BGP session, such as a hold timer expiring, neighbor capabilities change, or a BGP session reset is requested. This causes the BGP connection to close.

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77
Q

Describe the BGP keep alive message

A

Keepalive messages are exchanged every one-third of the Hold Timer agreed upon between the two BGP routers.

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78
Q

What is Kubernetes?

A

Kubernetes, or k8s (k, 8 characters, s…get it?), or “kube” if you’re into brevity, is an open source platform that automates Linux container operations.

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79
Q

How does kubernetes enhance linux container operations?

A

It eliminates many of the manual processes involved in deploying and scaling containerized applications.

Cluster together groups of hosts running Linux containers, and manage with Kubernetes.

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80
Q

What can the clusters span?

A

public, private and hybrid clouds

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81
Q

Why is Kube needed?

A

Real production apps span multiple containers. Those containers must be deployed across multiple server hosts. Kube is needed to manage containers.

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82
Q

What does Kube orchestration do?

A

Kubernetes orchestration allows you to build application services that span multiple containers, schedule those containers across a cluster, scale those containers, and manage the health of those containers over time.

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83
Q

What other services does Kube need to integrate with?

A

networking, storage, security, telemetry and other services to provide a comprehensive container infrastructure.

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84
Q

How does Kube help with container proliferation?

A

By sorting containers together into a ”pod.”

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85
Q

What is the primary advantage of using Kube?

A

Platform to schedule and run containers on clusters of physical or virtual machines.

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86
Q

What can you do with Kube?

A
  • Orchestrate containers across multiple hosts. -Make better use of hardware to maximize resources needed to run your enterprise apps. -Control and automate application deployments and updates. -Mount and add storage to run stateful apps. -Scale containerized applications and their resources on the fly. -Declaratively manage services, which guarantees the deployed applications are always running how you deployed them. -Health-check and self-heal your apps with autoplacement, autorestart, autoreplication, and autoscaling.
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87
Q

What additional projects does Kube rely on?

A

Registry, through projects like Atomic Registry or Docker Registry. Networking, through projects like OpenvSwitch and intelligent edge routing. Telemetry, through projects such as heapster, kibana, hawkular, and elastic. Security, through projects like LDAP, SELinux, RBAC, and OAUTH with multi-tenancy layers. Automation, with the addition of Ansible playbooks for installation and cluster life-cycle management. Services, through a rich catalog of precreated content of popular app patterns.

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88
Q

What is the master container?

A

The machine that controls Kubernetes nodes. This is where all task assignments originate.

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89
Q

What is a node?

A

These machines perform the requested, assigned tasks. The Kubernetes master controls them.

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90
Q

What is a pod?

A

A group of one or more containers deployed to a single node.

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91
Q

What does Ansible do?

A

IT automation engine that automates cloud provisioning, configuration management, application deployment, intra-service orchestration, and many other IT needs.

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92
Q

How does Ansible work?

A

Ansible works by connecting to your nodes and pushing out small programs, called “Ansible modules” to them.

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93
Q

What does Ansible use?

A

YAML, in the form of Ansible Playbooks that allow you to describe your automation jobs in a way that approaches plain English.

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94
Q

Where is Ansible stored?

A

library of modules can reside on any machine, and there are no servers, daemons, or databases required.

Works with any terminal editor

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95
Q

What is a docker container?

A

A Docker container image is a lightweight, standalone, executable package of software that includes everything needed to run an application: code, runtime, system tools, system libraries and settings.

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96
Q

When does a container image become a container?

A

Container images become containers at runtime and in the case of Docker containers - images become containers when they run on Docker Engine.

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97
Q

Which docker containers run on docker engine?

A

-Standard: Docker created the industry standard for containers, so they could be portable anywhere

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98
Q

What does Openstack do?

A

OpenStack software controls large pools of compute, storage, and networking resources throughout a datacenter, managed through a dashboard or via the OpenStack API.

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99
Q

What is Openstack?

A

OpenStack is a cloud operating system that controls large pools of compute, storage, and networking resources throughout a datacenter, all managed through a dashboard that gives administrators control while empowering their users to provision resources through a web interface.

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100
Q

What is PBTS?

A

PBTS provides a mechanism that lets you direct traffic into specific TE tunnels based on different criteria.

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101
Q

What doe the mpls te tunnel priority values represent? What should higher bandwidth links have?

A

preferred (setup) and (hold) priority. Higher bandwidth links should have higher priority and will preempt.

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102
Q

What is TDM?

A

Time Division Multiplexing. a collection of 64 kbps channels, called DS0s, which are aggregated into a larger bundle to form T1/T3, E1/E3 specifications.

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103
Q

How much traffic does a DS0 carry?

A

8 bits every 125 us, which is 64 kbps.

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104
Q

How many DSOs in a T1?

A

24

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105
Q

What is the T1 line rate?

A

1.544 Mbps

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106
Q

How big is the T1 frame?

A

193 bits, 1 frame bit for OAM

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107
Q

What is the speed and bits for a T3?

A

44.736 Mbps with 28 DS1s + 69 frame bits

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108
Q

What is DWDM?

A

Dense WDM is an enhancement to the original WDM (coarse WDM) to stuff more wavelengths onto a single medium, which increases the bandwidth.

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109
Q

What is needed at each end of the DWDM link?

A

Multiplexer and de-multiplexer to combine and restore the signal

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110
Q

What is an OSC?

A

Optical Supervisor Channel can also be transmitted over the same optical medium to serve OAM purposes; it is analogous to SONET’s DCC.

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111
Q

What types of modulation are supported?

A

AM, FM, PSK, QAM, and others.

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112
Q

What is the major benefit of using DWDM?

A

It can expand optical capacity without having to lay more fiber as channel spacing between wavelengths becomes smaller.

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113
Q

What is DWDM most commonly used for?

A

commercial long-haul systems and often uses C-band frequencies.

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114
Q

What is DSL?

A

Digital Subscriber Line - widely deployed “last-mile” access technology passes digital data over telephone lines by using a different set of frequencies than are used to carry phone conversations.

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115
Q

What components comprise DSL?

A

A DSL connection is generally comprised of a DSL modem at the customer end and a DSL access multiplexer (DSLAM) at the provider end.

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116
Q

What does the DSLAM do?

A

The DSLAM aggregates many DSL connections and, using some kind of transport media like ATM or Ethernet, connects to the BRAS

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117
Q

What are the BGP Path attributes?

A
  • Weight
  • Local Preference
  • Accumulated IGP (AIGP)
  • Locally originated
  • better than BGP learned
  • AS-path length
  • Origin
  • MED Multi exit discriminator
  • Neighbor type
  • IGP metric to the next hop
  • Tie breakers IGP cost-community Multipath For eBGP only, select the oldest route For iBGP or eBGP - Always compare RID For iBGP - select route with lowest cluster-list length Lowest Peer address
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118
Q

Describe Weight

A

Optional, local only. Higher is better, and locally originated prefixes are assigned a value of 32,768 by default.

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119
Q

Describe Local Preference

A

Mandatory, non-transitive. Higher is better with a default value of 100. Typically assigned inbound to an eBGP peer to affect traffic flows outbound. This attribute is maintained across confed-external boundaries.

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120
Q

Describe Accumulated IGP

A

Allows BGP to add the IGP metric to the BGP next-hop with the remote ASes metric value. Effectively, it is an end-to-end cost carried inside of BGP.

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121
Q

Describe Locally originated better than BGP learned

A

routes locally originated by a router (“sourced”) are preferred over any learned BGP routes.

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122
Q

Describe AS-path length

A

Mandatory, transitive, and well-known. The local AS is appended to an UPDATE message when routes are advertised out of an AS. AS path pre-pending is commonly set outbound to influence traffic flows inbound (opposite utility as local preference).

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123
Q

Describe Origin

A

Mandatory, transitive, and well-known. IGP implies the route was derived from IGP (network statement),

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124
Q

Describe Multi-exit discriminator (MED):

A

Optional, non-transitive. Used to carry the IGP metric to remote ASes to “hint” at the best path within the source AS network. Can be set outbound to influence flows inbound.

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125
Q

Describe Neighbor type

A

eBGP preferred over iBGP. Confed-external is treated the same as confed- internal, so this would be a tie in that case.

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126
Q

Describe IGP metric to the BGP next hop

A

Computed locally based on the recursive route lookups. Lower numbers are preferred

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127
Q

Describe the IP cost-community

A

Optional, non-transitive. If the IGP point of POI (which is the default) is passed in a prefix via extended communities, it is considered as the first “tie breaker”.

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128
Q

Describe Multipath

A

Multipath rules can be relaxed for iBGP unequal cost (where the IGP metric can be unequal), as well as the AS-path numbers.

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129
Q

Describe For eBGP only, select the oldest route:

A

This appears at the bottom of the route details when using the “show bgp afi safi x.x.x.x” command. The idea is to reduce churn in the eBGP topology by selecting the most stable route.

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130
Q

Describe For iBGP or eBGP with the “always compare RID”

A

Select the route coming from the lowest BGP RID.

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131
Q

Describe For iBGP, select the route with the lowest cluster-list length:

A

The idea is to pick the route that was reflected the fewest number of times.

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132
Q

Describe Lowest peer address:

A

This is the final tie-breaker it is the lowest peer address where the TCP session is established.

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133
Q

What are BGP pre-checks before best path attributes are compared?

A
  1. Next-hop reachability: Mandatory, well-known, and transitive. There must be a route to the BGP next-hop.
  2. iBGP synchronization: Often off by default, this rule states that for an iBGP route to be considered for best-path, there must be a matching IGP route in the routing table.
  3. Pre-bestpath cost-community: Optional, non-transitive.
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134
Q

What is SR?

A

Segment Routing - The idea is that individual nodes and adjacencies have segment IDs (SIDs), and each segment has label bindings.

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135
Q

What is SRGB?

A

(segment routing global block) s the range of label values reserved for Segment Routing and must not overlap with the global MPLS label range allocation.

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136
Q

What is GMPLS?

A

GMPLS is an extension of the MPLS. Given an all-optical network, traffic is often carried over these fibers in multiple different wavelengths. These different light waves are multiplexed (mux’ed) at the head-end and demultiplexed (demux’ed) at the tail end of the path.

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137
Q

Why use GMPLS?

A

Guarantee connectivity. GMPLS seeks to provide a mechanism to set up “light paths” from end to end based on a set of constraints.

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138
Q

Does GMPLS support bi-directional LSPs?

A

Yes. If using this feature, the requirements for the LSP are the same in both directions, which reduces latency during setup time.

139
Q

What is MPLS-TP?

A

MPLS TP is a mechanism to adjust typical MPLS behavior (technically IP/MPLS) to better emulate TDM networks.

140
Q

Which features of IP/MPLS are not supported in MPLS-tp?

A
  1. PHP: MPLS-TP paths are statically configured and highly explicit,
  2. ECMP: MPLS-TP requires all paths to be congruent (symmetric)
  3. Label merge: When two LSPs reach a common LSR and have a common next-hop, their LSPs can be merged by using a single outgoing-label. This is not allowed in MPLS-TP since every LSP is entirely different, again, like a traditional circuit.
141
Q

What benefits does MPLS-TP support over IP/MPLS?

A
  1. No need to configure IP:
  2. Advanced OAM: Rich set of tools to monitor and manage the MPLS-TP and the PWs that run through it. This includes the Generic Alert Label (GAL) and the Generic Associated Channel (G- ACH). In summary, this provides SONET/SDH-like features such as automatic protection switching (APS) and data communications channel (DCC).
  3. Fault reporting:
142
Q

What is QinQ?

A

QinQ (dot1q tunneling or provider bridging) is a method of adding additional 802.1q headers to an Ethernet frame to tunnel it across different networks.

143
Q

What is 802.1ad?

A

802.1ad is an amendment to 802.1q which allows them to be stacked in an Ethernet frame’s header.

144
Q

What are the benefits to tag stacking?

A
  1. Adding an additional tag squares # of VLANs (2^24 = 16777216)
  2. Tags can be added (pushed), removed (popped), or changed (translated) by network devices as necessary.
  3. Provides the basis for provider bridging and provider backbone bridging (PBB)
145
Q

What is the standard ethertype?

A

0x88A8 for the outer tag (service tag, carrier tag, metro tag, tag 1, or S- tag)

0x8100 for the inner tag (customer tag, tag 2, or C-tag).

146
Q

What is 802.1ah MAC in MAC (Provider Backbone Bridges)?

A

B-MACs are service provider switch MACs that serve as the outer encapsulation for customer traffic. In this way, provider switches don’t need to learn all C-MACs, only B-MACs, of which there is one per PE.

147
Q

What is REP?

A

REP is a Cisco-proprietary protocol that is used to rapidly converge a layer 2 Ethernet network arrayed in a ring topology.

148
Q

Describe G.8032?

A

Also known as Ethernet Ring Protection Switching (ERPS). A segment is called a “ring” and an independent link between two ring nodes is called a “ring link”. The ports that run this protocol on ring links are called “ring ports”. The alternate (blocked) port is known as the ring protection link, or RPL. The node that is actually blocking a port is known as the “RPL owner node”.

149
Q

How does G.032 use CFM?

A

ERPS registers to CFM as a client.

150
Q

Describe QoS Link fragmentation (LFI)?

A

QoS link fragmentation and interleaving (LFI) is a common technique for slow WAN links to reduce latency for priority traffic.

Large data packets take longer to serialize over slow WAN links than small voice packets do.

151
Q

What is serialization delay?

A

Delay (sec) = size (bits) / rate (bits/sec) - As an example, a 1500 byte packet (12000 bits) going over a T1 link (1544000 bps) will take about ~8ms (0.008 seconds) to serialize.

152
Q

What is the slowest link that VoIP can use?

A

768 kbps (half T1) is the cutoff for a slow link.

153
Q

What is SSO?

A

Stateful switchover. RSP/RP to be written to the backup one so that it can immediately take over if the primary one fails.

154
Q

What is NSF?

A

Non-stop forwarding. During an SSO event, NSF ensures that despite a brief loss of the control plane due to an RSP/RP failure, traffic can still be forwarded.

155
Q

What is NSR?

A

Maintains the routing protocol information during an SSO event. BGP sessions can remain intact. NSR is available with OSPFv2/v3, IS-IS, BGP, LDP routing technologies currently. RVSP-TE, EIGRP, and RIP are not included.

156
Q

Does ISIS support NSR and NSF?

A

Yes. IS-IS supports both NSF and NSR. The NSF capability of IS-IS is signaled using the Restart TLV, which is carried in the hello PDUs

157
Q

Does OSPFv2 support NSR and NSF?

A

Yes. NSF requires some extensions to OSPF so that the peer routers remain aware of the restarting router. OSPF uses new “grace LSAs”, which are link-local opaque LSAs containing the grace period time in their payloads.

158
Q

What is NSF called in OSPFv3?

A

OSPFv3 calls NSF “graceful-restart”.

159
Q

Describe BGP NSR and GR

A

BGP GR’s primary purpose is the same as the other protocols: don’t introduce churn into the protocol while a router switches over, specify a grace period, and continue forwarding as normal. BGP accomplishes this by introducing the End-of-RIB (EoR) marker, as well as a new “Graceful Restart” capability.

160
Q

What is EoR?

A

Marks the end of RIB, it is effectively an explicit signal to the peer that the BGP UPDATE messages have ceased.

161
Q

Does LDP support GR and NSF?

A

Yes. Although not a routing protocol, LDP is critical for most MPLS applications. It also has the concept of GR/NSF and NSR for this reason.

162
Q

Does RSVP-TE support GR and NSF?

A

Just GR is used to maintain state information when a node in the LSP performs an RP switchover.

163
Q

Does EIGRP support GR or NSF?

A

EIGRP supports GR/NSF but not NSR.

164
Q

What is carrier delay?

A

A timer that runs in software to identify when a link goes down at layer 1. This is normally set to 2 seconds to prevent against very short flaps, which may introduce churn.

165
Q

What is BGPsec?

A

A BGP prefix is cryptographically signed with the key of its valid originator, and each BGP router receiving the path checks to ensure the prefix originated from the valid owner.

166
Q

Describe performance management and capacity procedures

A

Performance management: practice of managing network service response time, consistency, and quality for individual and overall services.

Capacity management: process of determining the network resources required to prevent a performance or availability impact on business-critical applications.

167
Q

Describe backscatter traceback

A

Forwarding of ICMP unreachables back into the core network and ultimately into a sinkhole for analysis.

168
Q

Describe lawful-intercept

A

This allows a mediation device to communicate to a router over SNMPv3 to setup/teardown wiretap sessions on a network device.

169
Q

Describe BGP Flowspec

A

Defines additional BGP NLRI to inject traffic manipulation policy information to be dynamically implemented by a receiving router. It can signal specific QoS actions, redirect traffic into a VRF for analysis, or drop the traffic.

170
Q

Describe DDoS mitigation techniques

A

ACLs, remotely triggered black holes, unicast RPF, backscatter traceback, and BGP Flowspec.

171
Q

Describe network event and fault management

A

Functions that detect, isolate, and correct malfunctions in the network.

172
Q

Describe performance management and capacity procedures Capacity management:

A

Performance management: practice of managing network service response time, consistency, and quality for individual and overall services.

process of determining the network resources required to prevent a performance or availability impact on business-critical applications.

173
Q

Describe Queuing

A

The larger the queue, the longer data has to wait. Tail drop occurs when the queue is full and admittance is prohibited.

174
Q

What are common areas for concern with capacity and performance?

A

a. CPU. Used by both control and data planes on any network device.
b. Backplane of I/O.
c. Memory and buffers.
d. Interface and pipe sizes.
e. Queuing, latency, and jitter.
f. Speed and distance.
g. Application characteristics. Small window sizes, application keepalives, and amount of data sent over the network versus what is required is often the reason for poor application performance.

175
Q

What are network best practices?

A

a. Service level management - SLA
b. Network and application what-if analysis.
c. Baselining and trending.
d. Exception management.
e. QoS management.

176
Q

What is NETCONF and YANG?

A

Network Configuration Protocol. It is a standard for configuring, deleting, and modifying configurations on network devices.

YANG is used to model the network configurations and state into tree structures; it is the data model for NETCONF.

177
Q

what additional features does NETCONF have?

A

Test configurations before committing them, being able to configure multiple network devices concurrently, and bulk-get operations that are much faster than SNMP.

NETCONF uses SSH

NETCONF messages are encoded in XML, and individual YANG data models are included as “capabilities” in NETCONF hello packets. .

178
Q

What are the benefits to YANG?

A

The structure contains several “types”, which include integers, Booleans, enumerations, pointers, and other information types to be processed.

179
Q

What is BGP RT-filter unicast / IPv4 RT-filter feature?

A

If a PE is only importing a subset of RTs, the RR will reflect all VPN routes to a PE where the majority of them are rejected due to the RT-import not being locally configured for any VRF.

180
Q

Why use AIGP?

A

Control flow of traffic.

181
Q

What is cost-community / Point of Insertion?

A

Carry cost information around BGP networks.

182
Q

What is BGP MVPN

A

Encompass all of the solutions meant to transport multicast traffic from place to place in a VPN environment.

183
Q

What was the original multicast solution?

A

Draft-Rosen, used GRE tunnels to connect all of the PE devices in a given MVPN instance

184
Q

Where is PIM applied

A

Customer and Core, P router just act as transit.

185
Q

What is supported in Rosen-GRE?

A

PIM-ASM, PIM-SSM, or PIM-Bidir in the core.

186
Q

What is the main issue with Profile 0?

A

It does not take advantage of MPLS transport.

187
Q

Can RSVP be used with Multicast?

A

Yes. P2MP RSVP-TE, a multipoint tunnel can be built from headend to multiple tail ends, which is perfect for transporting one-way multicast.

188
Q

Can LDP be used with Multicast?

A

Yes. multicast LDP (mLDP).

189
Q

What is PMSI? and what does it do?

A

Provider Multicast Service Interface is a conceptual “overlay” on the P-network that refers to a “service”.

Packets are encapsulated in IP/GRE or MPLS and delivered to the PMSI where they are de-capsulated.

190
Q

What is Type 1 PMSI?

A

Intra-AS Inclusive PMSI (I-PMSI) AD: Originated by each PE inside an AS; used to learn MVPN membership.

191
Q

What is Type 2 PMSI?

A

Inter-AS I-PMSI AD: Originated by each ASBR; used to learn MVPN membership. This is examined in detail when testing inter-AS MVPN.

192
Q

What is Type 3 PMSI?

A

Selective (S-PMSI) AD: Originated by the source (ingress) PE and used for signaling a specific P2MP tree or data MDT.

This is meant to selectively target receivers that want multicast for a given C(S,G).

193
Q

What is Type 4 PMSI?

A

Leaf AD: If the Type-3 requests it, the receiver (Egress) PEs will explicitly show interest in a specific C(S,G).

194
Q

What is Type 5 PMSI?

A

Source Active AD: Originated by the source (ingress) PE when it learns about an active source and assist with SPT switchover.

195
Q

How do customers exchange PIM?

A

The method by which customers exchange multicast routing has always been PIM.

196
Q

What is Type 6 PMSI?

A

Shared Tree Join: Specifies the RP and group, and is meant to signal C-PIM-ASM interest in a particular group. This replaces the PIM (*,G) signaling.

197
Q

What is Type 7 PMSI?

A

Source Tree Join: Looks identical to a Type-6 except the RP’s IP address is substituted for the source’s address. It can also be sent upon receipt of a Type-5 Source Active AD message. This replaces the PIM (S,G) signaling.

198
Q

How is C-Multicast carried outside of PIM/BGP?

A

mLDP is also capable of carrying the c-mcast signaling in-band.

199
Q

How does a router decide on what P tunnel to use?

A

It needs to look at the I-PMSI or S-PMSI to determine the tunnel type. Each transport method has a different tunnel type.

200
Q

Where is the I-PMSI and S-PMSI attributes carried?

A

Inside the PMSI attributes within BGP AD routes

201
Q

How do tunnels encapsulate and decapsulate packets? Can there be a mismatch?

A

Type 0: No tunnel specified Type 1: RSVP-TE P2MP Type 2: mLDP P2MP Type 3: PIM-SSM Type 4: PIM-ASM Type 5: PIM-Bidir Type 6: Ingress Replication (IR) Type 7: mLDP MP2MP

No.

202
Q

What is BGP-LS?

A

BGP-LS is designed to capture link state IGP and TE information and transport it across the network.

203
Q

What is profile 1

A

Default MDT − MLDP MP2MP − PIM C−mcast Signaling (Basic mLDP) The MP2MP tree is a bidirectional tree that represents and emulated LAN. When used with C- PIM signaling, it forms a full-mesh of all VPN participants, which is determined by the VRF’s VPN-ID.

204
Q

What is profile 3?

A

Default MDT − GRE − BGP−AD − PIM C−mcast Signaling

205
Q

What is profile 6?

A

VRF MLDP − In−band Signaling

206
Q

What is profile 7?

A

Global MLDP In−band Signaling

207
Q

What is Profile 8?

A

Global Static − P2MP−TE P2MP

208
Q

What is Profile 9?

A

Default MDT − MLDP − MP2MP − BGP−AD − PIM C−mcast Signaling

209
Q

What is Profile 10?

A

VRF Static – P2MP TE - BGP−AD

210
Q

What is profile 11?

A

Default MDT − GRE − BGP−AD − BGP C−mcast Signaling

211
Q

What is profile 12?

A

Default MDT − MLDP − P2MP − BGP−AD − BGP C−mcast Signaling

212
Q

What is profile 13?

A

Default MDT − MLDP − MP2MP − BGP−AD − BGP C−mcast Signaling

213
Q

What is profile 14?

A

Partitioned MDT – MLDP P2MP – BGP-AD – BGP C-mcast signaling

214
Q

What is profile 17?

A

Default MDT – MLDP P2MP – BGP-AD – PIM C-mcast signaling

215
Q

What is Multicast on Fast Reroute?

A

MoFRR is a feature used to ensure high availability for multicast traffic.

216
Q

What is an MVPN extranet?

A

Networks that have been extended outside of an intranet to provide reachability to external organizations. an MVPN extranet exists when sources are in one VPN and receivers are in another VPN.

217
Q

What is FRR with MPLS-TE?

A

If a link or node within the path of a TE tunnel fails, a pre-signaled backup path is available and traffic can be routed into the backup tunnel as soon as the failure is detected.

218
Q

What is PLR?

A

The point of local repair is the head-end of the backup path. When a failure is detected, it routes packets into the backup tunnel.

219
Q

What is MP?

A

The merge point is the tail-end of the backup path. When traffic arrives at the MP, it is routed along the normal TE path again, merging the traffic back on the original path.

220
Q

What is Path Protection?

A

Pre-signals a backup path from head to tail on a per path-option basis to be used in case of a failure anywhere along the path.

221
Q

What is NHOP protection?

A

Next-hop protection (link protection) protects the path to the next-hop by routing around failed links.

222
Q

What is NNOP Protection?

A

Next-next-hop protection (node protection) protects the path to the hop after the next-hop by routing around failed nodes.

223
Q

What are the two ways of achieving FRR with RFC4090?

A
  1. N:1 or many-to-one or facility backup. The PLR pushes a new FRR label (wraps the existing MPLS packet) as part of a new TE tunnel.
  2. 1:1 or one-to-one or detour backup. The PLR swaps the top label rather than pushes a new one.
224
Q

How does PBTS/CBTS work?

A

Class and Policy Based Tunnel Selection (CBTS/PBTS) are mechanisms of mapping EXP values to different tunnels in XE and XR, respectively.

225
Q

What are 5 things the Control Word is capable of?

A
  1. Pad small packets:
  2. Carry control bits for certain layer 2 protocols
  3. Preserve the sequence of frames
  4. Facilitate load sharing
  5. Facilitate fragmentation/reassembly: Using Beginning and Ending (B and E) bits, AToM frames can be fragmented and reassembled for transit over MPLS. P routers cannot fragment AToM packets.
226
Q

What is Multisegment PW stitching?

A

a way to terminate PWs on a common node and have that router bridge the two PWs together. In this way, the PW is “stitched” to provide layer-2 transport end to end.

227
Q

Describe the BGP holdtime

A

Sets the Hold Timer in seconds for each BGP neighbor. Upon receipt of an UPDATE or KEEPALIVE, the Hold Timer resets to the initial value.

228
Q

Which BGP holdtime is preferred? What is the minimum holdtime?

A

Smaller, 3 seconds or 0

229
Q

Describe the BGP router-id

A

32-bit unique number that identifies the BGP router in the advertised prefixes as the BGP Identifier. The RID can be used as a loop prevention mechanism for routers

230
Q

What does a pod do in regards to Kube?

A

Pods add a layer of abstraction to grouped containers, which helps you schedule workloads and provide necessary services like networking and storage to those containers.

231
Q

How else can Kubernetes help with pods?

A

Other parts of Kubernetes help you load balance across these pods and ensure you have the right number of containers running to support your workloads.

232
Q

What is the advantage of a container?

A

Containers isolate software from its environment and ensure that it works uniformly despite differences for instance between development and staging.

233
Q

Will containerized software always run the same?

A

Yes, regardless of infrastructure, available for windows and linux

234
Q

How does PBTS work?

A

PBTS works by selecting tunnels based on the classification criteria of the incoming packets, which are based on the IP precedence, experimental (EXP) , or type of service (ToS) field in the packet.

235
Q

Who benefits by using PBTS?

A

PBTS will benefit Internet service providers (ISPs) who carry voice and data traffic through their MPLS and MPLS/VPN networks, who want to route this traffic to provide optimized voice service.

236
Q

What is WDM?

A

Wavelength division multiplexing (WDM) is a method of transmitting many different wavelengths of light onto a single fiber media.

237
Q
A
238
Q

What does DWDM run on? What is the diameter?

A

single-mode fiber, which is built for long-haul transmissions at higher data rates and has a diameter of 9 um.

239
Q

What is the core diameter of MMF?

A

62.5 um

240
Q

Within the BGP AS-path attribute, how are confederations identified?

A

Within a confederation, the values are placed into a parenthesized list and treated as a single AS.

241
Q

What 3 main components comprise PBB?

A
  1. Backbone component: Contains a destination address (B-DA), source address (B-SA), the ethertype 0x88A8 as defined in 802.1ad for QinQ tunneling, and a B-tag to represents the backbone VLAN.
  2. Service component: Contains ethertype 0x88E7 (defined for PBB) and an I-SID (24-bit service ID).
  3. Original frame: This could be an IP packet inside of an Ethernet frame (0x0800), an Ethernet frame inside of dot1q with a single C-tag (0x8100), or part of a hierarchical bridging architecture with two tags already on it (0x88A8).
242
Q

What are the ERP messages called?

A

ring automatic protection switching (R-APS) series of messages.

243
Q

How does ERP handle link failure?

A

A failure along the ring triggers an R-APG signal failure (R-APS SF) failure, and when the RPL owner receives this message, the port is immediately unblocked.

244
Q

Is CFM required for ERP?

A

Switches participating in ERPS must be part of the same CFM domain as a prerequisite to ERPS working.

245
Q

Are CFM MEPS required for ERP?

A

No, but it is recommended to configure CFM MEPs; although this is not required, it allows for additional CFM monitoring

246
Q

How does backscatter traceback work?

A

combines ACLs, remotely triggered blackholes (sometimes), sinkholes, and ICMP unreachables to determine the ASBR ingress routers from which an attack has entered the network.

247
Q

What else does GR do for EIGRP?

A

it also assists with stuck-in-active (SIA) events where a route has unanswered queries from at least one peer regarding its reachability status.

248
Q

How is the RS-bit used in EIGRP GR?

A

the restart bit (RS-bit) is set in the hello packets towards all peers. Those who receive and understand this message immediately send their EIGRP topology tables to the restarting router. When complete, an end-of-table (EoT) message is sent to signal the end of the topology transfer.

249
Q

Does BGP flowspec occur in the control plane or data plane?

A

Data plane, even though the rules are written into the NLRI

250
Q

What is RTBH?

A

Remotely triggered black holes - blackholes traffic to/from certain prefixes during a DDoS attack.

251
Q

Describe latency

A

latency refers to any of several kinds of delays typically incurred in processing of network data.

252
Q

Describe Jitter

A

variation in the latency on a packet flow between two systems, when some packets take longer to travel from one system to the other.

253
Q

Describe RSVP-TE

A

Like a normal TE tunnel, each sub-tunnel (also called sub- LSP) can request FRR treatment, make bandwidth reservations, and do any other kind of TE CSPF parameter tuning.

254
Q

How does MLDP work?

A

This works like LDP where labels are exchanged on a hop-by-hop basis.

255
Q

What kind of trees does MLDP support?

A

mLDP can support P2MP trees, It can also support MP2MP trees, which are similar to PIM-Bidir where traffic can flow in either direction towards the root, which is the main junction point.

256
Q

How are labels are assigned in MP2MP trees?

A

upstream and downstream labels are exchanged.

257
Q

Which is more efficient, P2MP or MP2MP?

A

P2MP - like PIM SSM

258
Q

Which uses less state, P2MP or MP2MP?

A

MP2MP - like PIM BSR

259
Q

How do customer exchange PIM in draft-rosen?

A

PEs would form PIM neighbors inside the VRF and the tunnel-mesh would look like an emulated LAN.

260
Q

How do customers exchange PIM in basic mLDP MP2MP trees?

A

Same as draft-rosen.

261
Q

Why was BGP extended to do c-mcast signalling?

A

To achieve better scalability

262
Q

What new c-mcast route-types does BGP introduce?

A

IPv4/v6 MVPN SAFI, PIM equivalent of (*,G) join and an (S,G) join.

263
Q

What is the result of receiving a PIM join from a CE in BGP?

A

Receiving a PIM (*,G) or (S,G) join from the CE will trigger the creation of a BGP Type-6 or Type-7 route, respectively.

264
Q

What is I-PMSI?

A

Inclusive-PMSI - The I-PMSI tunnel connects to all PEs on the MVPN and sends multicast data to these PEs regardless of whether these PEs have receivers.

265
Q

What is S-PMSI?

A

Selective-PMSI - S-PMSI tunnels solve the I-PMSI problem by sending multicast data only to PEs interested in the data.

266
Q

How does MoFRR work?

A

adjusts how RPF works with traditional PIM. When the PIM last hop router (LHR) receives an IGMP join, whether ASM or SSM, it will originate some kind of PIM join.

MoFRR allows a router to send multiple PIM joins towards the root of the tree for diversity.

267
Q

What are some reasons to add virtualization in the POP and Data Center?

A
  • Reduce CAPEX (Fewer Chassis)- Reduce OPEX (deploy fewer chassis, simplify topologies)- Reduce environmental impact
268
Q

What are the two main types of virtualized router entities, as defined by their physical and operational characteristics?

A
  • A Hardware-Isolated Virtual Router (HVR) has hardware-based resource isolation between routing entities.- A Software-Isolated Virtual Router (SVR) comprises software-based resource isolation between routing entities.
269
Q

Within SVR, what are some models for achieving virtualization?

A
  1. Multiple guest operating systems to overlay on a host operating system.2. Integrate the virtualization into the kernel itself.3. Virtualization is in the individual applications.
270
Q

What is the impact of using the SVR overlay model?

A

Doesn’t scale well because it introduces significant contention of resources and users tend to over provision resources on all SVRs wasting resources.

271
Q

What is the impact of integrating the virtualization in the kernel with SVR?

A

This model may improve processing performance but suffers from resource contention and increased complexity and instability in the kernel.

272
Q

What is the impact of providing virtualization in the applications with SVR?

A

Scales better because of lower overhead but complicates a number of issues because the application must some level of virtualization.

273
Q

Does SVR share data plane or control plane resources?

A

Yes. All SVR models share resources in the data plane, requiring vigilant resource monitoring.

274
Q

Does HVR share data plane and control plane?

A

No. It dedicates both control and data plane resources on a per-module boundary to individual virtual entities so there is no sharing of resources, other than a lightweight shim layer that provides low-level communication between HVRs.

275
Q

What HVR technology does Cisco IOS XR provide support for?

A

Secure Domain Routers (SDRs)

276
Q

Define SDR

A

An HVR technology that provides full isolation between virtual routing instances through the use of Distributed Route Processors (DRPs) for extra control plane resources.

277
Q

How are SDRs defined on a per-slot boundary?

A

With entire Route Processors (RPs) and Modular Services Cards (MSCs) dedicated to an SDR.

278
Q

Describe Satellite network virtualization

A

Satellite switches act as extensions to the ASR9k, they are under the complete control and configuration management of the host router.

279
Q

What is the main advantage to using Nv?

A

Port Density - A single 24-port Ten Gigabit Ethernet line card on the Cisco ASR 9000 Series Router could integrate up to 24 satellite switches each with 44 GigE ports; this results in an effective port density of 1056 Gigabit Ethernet ports for each Cisco ASR 9000 Series Router line card slot.

280
Q

What types of topologies are supported by the Satellite System?

A

Hub and Spoke network topologyDual Home network topologySimple Ring topologyLayer 2 Fabric network topology

281
Q

Does the Nv switch have to be co-located with the host router?

A

No, they can be in geographically distinct locations

282
Q

What is NFV?

A

Network Function Virtualization - decouples network functions from hardware and puts them in software. Example: vFirewalls, vRouters, load balancer, etc.

283
Q

In Long term evolution (LTE), what is the UE?

A

User equipment like a cellphone. Each UE carries a Universal integrated circuit card (UICC) In LTE the cellphone carries a Subscriber Identity module (SIM) which identifies a phones number, billing plan, etc.

284
Q

Describe eNobeB

A

These are base stations that control the mobile nodes in one or more calls. A base station that is supporting a specific mobile node is reference as the mobile node’s “serving eNB”. LTE mobile nodes can only communicate with one base station at a time.

285
Q

What are the 2 primary functions of eNB?

A

Send/receive radio transmissions and to control low-level signaling such as handover commands.

286
Q

Why are eNBS connected to each other?

A

To support mobility events for packet forwarding and handover using the X2 interface.

287
Q

What interface does the eNB use to communicate with upstream networks?

A

S1 interface.

288
Q

How do UEs talk to eNBs?

A

Via the LTE-Uu interface.

289
Q

Describe RAN

A

(Radio Access Network) This is a way of providing backhaul from access networks to the provider’s core network.

290
Q

What is UMTS?

A

Universal Mobile Telecommunications System - This was the third generation 3G network upon which 4G LTE was built. This was a combination of circuit and packet switched architectures which was more hierarchical.

291
Q

What is E-UTRAN?

A

Evolved UMTS Terrestrial RAN. This encompasses the entire LTE access network, which consists of eNB radios.

292
Q

What is BTS?

A

Base transceiver station - eNB, is the element in E-UTRA of LTE that is the evolution of the element Node B in UTRA of UMTS. It is the hardware that is connected to the mobile phone network that communicates directly wirelessly with mobile handsets (UEs), like a base transceiver station (BTS) in GSM networks.

293
Q

What is the Uniform QoS model?

A

Uniform is a QoS model whereby changes in the SP network are propagated to the customers.

294
Q

What is QPPG?

A

QoS Policy Progagation through BGP - BGP NLRI carries the QoS markings for specific routes

295
Q

In Ios, how do you push traffic over a designated VPWS PW?

A

Under the AC interface add the command ‘preferred-path interface Tunnel85’

296
Q

How is traffic stitched in a VPLS?

A

PW and VFI are bridged. Bridge domain acts like l2 switch, PW intefaces and VFI act like connections to a switch.

297
Q

How are MACs learned over VPLS?

A

Through the flood and learn approach

298
Q

What defines PE membership in a VPLS domain?

A

The route-target.

299
Q

What is GCC1 and GCC2?

A

General communications channel - defined by G.709 is an in-band side channel used to carry transmission management and signaling information within optical transport network elements.

Four bytes (each of two bytes) within ODUk overhead. These bytes are used for client end-to-end information and shouldn’t be touched by the OTN equipment.

300
Q

What is a TE Mesh group?

A

MPLS Traffic Engineering AutoTunnel Mesh Groups (referred to as mesh groups) allow a network administrator to configure traffic engineering (TE) label-switched paths (LSPs) by using a few command line interface (CLI) commands.

301
Q

How does a member get added to an auto-tunnel mesh?

A

you must configure each existing TE LSR to be a member of the mesh by using a minimal set of configuration commands.

302
Q

What is the benefit of Mesh groups?

A
  • Minimize the initial configuration of the network. You configure one template interface per mesh that propagates to all mesh tunnel interfaces, as needed.
  • Minimize future configurations resulting from network growth. Eliminates the need to reconfigure each existing TE LSR in order to establish a full mesh of TE LSPs whenever a new PE router is added to the network.
  • Existing routers set up TE LSPs to new PE routers.
  • Automatically construct a mesh of TE LSPs among the PE routers.
303
Q

How do you setup a mesh of tunnels?

A
  • Enable autotunnel mesh groups globally. See the “Enable AutoTunnel Mesh Groups Globally” section.
  • Create an access-list.
  • Create one or more template interfaces.
304
Q

What is the ACL used for in auto tunnel mesh setup?

A

The access-list determines the destination addresses for the mesh tunnel interfaces.

305
Q

What is the purpose of the template interface with auto-tunnel mesh?

A

The template interface allows you to enter commands once per mesh group. These commands specify how mesh tunnel interfaces will be created. Each time a new router is added to the network, a new mesh tunnel interface is created and that configuration is duplicated from the template. Each mesh tunnel interface has the same path constraints and other parameters configured on the template interface. Only the tunnel destination address is different.

306
Q

How do you specify a range of mesh tunnel interfaces?

A

mpls traffic-eng auto-tunnel mesh tunnel-num min 1000 max 2000

307
Q
A
308
Q

Describe ECP

A

Embedded Packet Capture is used in Cisco IOS on the router and captures the packets sent and received. The packets are stored within a buffer in DRAM and are thus not persistent through a reload. Once the data is captured, it can be examined in a summary or detailed view on the router.

309
Q

How can packets be viewed using EPC?

A

exported into PCAP (Wireshark), or on the router.

310
Q

What is the basic EPC config

A

Basic EPC Configuration

Define the location where the capture will occur:

Associate a filter. The filter may be specified inline, or an ACL or class-map can be referenced:

Start the capture:

The capture is now active. Allow it to collect the necessary data.

Stop the capture:

Examine the capture in a summary view:

Examine the capture in a detailed view:

In addition, export the capture in PCAP format for further analysis:

Once the necessary data has been collected, remove the capture:

311
Q

What interfaces are supported with EPC?

A

The capture can be performed on physical interfaces, sub-interfaces, and tunnel interfaces.

312
Q

Name the standards AFIs

A

1 - IPv4

2- IPv6

313
Q

Name the standard SAFIs

A

sub-address family idenitifiers

SAFI/Meaning

1 Unicast

2 Multicast

3 Unicast and multicast

4 MPLS Label

128 MPLS-labeled VPN

314
Q

What are the two BFD modes?

A

There are two operating modes to BFD, asynchronous mode and demand mode.

315
Q

How does BFD operate in Asynchronous mode?

A

The asynchronous mode is similar to the hello and holddown timers, BFD will keep sending hello packets (called BFD control packets) and when you don’t receive some of them, the session is teared down.

316
Q

How does BFD operate in Demand mode?

A

once BFD has found a neighbor it won’t continuously send control packets but only uses a polling mechanism. Another method has to be used to check reachability, for example it could check the receive and transmit statistics of the interface.

317
Q

What is echo mode for BFD?

A

Both modes also support something called echo mode. When a device sends BFD echo packets then the receiver will return them without processing them. When the sender doesn’t get the echo packets back, it knows something is wrong and will tear down the session.

318
Q

Describe 2547oDMVPN

A

MPLS over DMVPN - DMVPN provides two key advantages for extending MPLS VPNs to the branches, bulk encryption and, more importantly, a scalable overlay model.

319
Q

How is MPLS extended to the branches in 2547odmvpn?

A

WAN edge router (Hub) is a P router that can label switch packets between branches.

Branches act as PE routers use LDP and IGP for signalling L3VPN

320
Q

What is the OSPF downward-bit used for in MPLS L3VPN?

A

Loop Prevention

321
Q

Where can the OSPF DN bit be set?

A

In the type 3, 5, 7 LSA and the domain-tag for type 5 and 7

322
Q

How does the DN-bit prevent loops?

A

When an OSPF LSA type 1 route is advertised to the PE2, then redistributed into VPNv4 and advertised to another PE2, then redistributed back into an OSPF area as a type 3 LSA with redundant uplinks. Route doesn’t get re-advertised back to BGP as locally originated route.

323
Q
A
324
Q

How does B4 operate?

A

The IPv4 packets entering B4 are encapsulated using a IPv6 tunnel and sent to the Address Family Transition Router (AFTR).

325
Q

What does the AFTR do?

A

This is the router that terminates the tunnel from the B4. It decapsulates the tunneled IPv4 packet, translates the network address and routes to the IPv4 network.

326
Q

What does the AFTR do with packets coming from the internet?

A

Reverse network address translated and the resultant IPv4 packets are sent the B4 using a IPv6 tunnel.

327
Q

What is the main characteristic of GPON?

A

Its main characteristic is the use of passive splitters in the fibre distribution network.

328
Q

How do splitters play a role in GPON?

A

They enable one single feeding fibre from the provider’s central office to serve multiple homes and small businesses.

329
Q

How does RSVP-TE allocate labels?

A

Headend router sends a PATH request first to the tail-end and then the Tail end router replies back with RESV which includes the FEC-to-Label mapping towards the head end.

330
Q
A
331
Q

What do containers in a pod share?

A

IP address, IPC, hostname, and other resources

332
Q

What do pods abstract from underlying container?

A

Network and storage which simplifies moving containers around cluster

333
Q

How are ansible modules written and executed?

A

Written to be resource models of the desired state of the system - how all systems inter-relate.

Ansible then executes these modules (over SSH by default), and removes them when finished

334
Q

What traffic can continue forwarding due to NSF?

A

functions like ARP, BFD, ACL, and QoS, because the LC has a FIB and can forward.

335
Q
A
336
Q
A
337
Q

Which TLVs are used in MPLS Traffic Engineering?

A

Extended IS neighbor TLV #22

Extended IS reachability TLV#135

Router ID TLV #134

338
Q

Which PIM mode is traffic routed only along a bidirectional shared tree that is rooted at the rendezvous point (RP) for the group

A

Bi-directional

339
Q

How is Bidir-PIM membership signalled?

A

Explicit Joins

340
Q
A
341
Q

What does bgp additional-paths install do?

A

Installs additional routes in RIB and CEF to same prefix destination.

342
Q

How does bgp additional-paths install improve routing?

A

Can limit hot potato routing, limit MED oscillations, help with mx, next-hop failures.

343
Q
A

CCIE SP Written Concepts (3 decks)

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