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JNCIS-SP > Junos Intermediate Routing (JIR) > Flashcards

Junos Intermediate Routing (JIR) Flashcards

1
Q

What is static routing?

A

Manually configured route to each a particular destination

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2
Q

What is a martian route?

A

Prefixes ignored by Junos OS in the sense that they are never installed in the routing table.

Default routes include:

  • 0.0.0.0/8 orlonger
  • 127.0.0.0/8 orlonger
  • 192.0.0.0/24 orlonger
  • 240.0.0.0/4 orlonger
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3
Q

What command will display all martian routes?

A

‘show route martians’

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4
Q

What are the six match types for martian routes?

A
  • exact
  • orlonger
  • prefix-length-range
  • through
  • upto
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5
Q

What command would remove a martian route?

A

configure edit routing-options

set martians 240/4 orlonger allow

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6
Q

What commands would add a martian route?

A

configure edit routing-options

set martians 240/4 orlonger

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7
Q

What is a routing instance?

A

A unique collection of routing tables, interfaces, and routing protocol parameters

also known as routing information base (RIB)

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8
Q

What is the master routing instance?

A

default unicast routing instance which includes the inet.0 and inet6.0 routing tables

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9
Q

What common situations would warrant a user-defined routing instance?

A
  • Filter-based forwarding (FBF)
  • Virtual Private Network (VPN) services
  • System Virtualization
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10
Q

What are some of the common routing instance types?

A
  • forwarding - used to implement FBF
  • l2vpn
  • no-forwarding - used to separate large networks into smaller admin entities
  • virtual-router - used for non-vpn related applications such as system virtualization
  • vpls - used for point-to-multipoint LAN implementations between a set of sites in a VPN
  • vrf - used in Layer 3 VPN implementations
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11
Q

What command would return the interfaces connected to a particular routing-instance?

A

‘show interface terse routing-instances ‘

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12
Q

What is a RIB Group?

A

A Routing Information Base group, aka Routing table

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13
Q

What is the purpose of RIB groups?

A

To share routes between routing tables

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14
Q

What are the configuration options within the rib-group configuration?

A
  • import-rib: can list multiple routing tables, and inform the software where to place incoming route information
  • export-rib: can list only one routing table, and inform the software where to extract route information
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15
Q

Identify the function of the configuration provided

A

Shares OSPF routes between inet.0 and test.inet.0

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16
Q

What is Equal-Cost Multipath Load Sharing?

A

Ability to distribute traffic destined to the same destination prefix over equal-cost paths simultaneously

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17
Q

Describe the difference between per-flow load balancing and per-packet load balancing

A

per-packet load balancing sends packets round-robin across all equal-cost links

per-flow maintains individual traffic flows between end statioons

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18
Q

What are the benefits of per-flow load balancing?

A
  • Packets generally arrive at the destination in the order sent resulting in less application delay.
  • QoS policies are easier to implement
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19
Q

What behavior is depicted in the provided screenshot?

A

Default Junos behavior

Only the selected next-hop is installed in the forwarding table as they are equal-cost.

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20
Q

What is the mechanism for changing the default load-balancing behavior?

A

Routing policies can be defined and applied to allow for individual flows to use all equal-cost paths.

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21
Q

What steps should Walter take to meet the objectives outlined in the image?

A
  • Define a load-balancing policy
  • Apply load-balancing policy
  • include the layer 3 and layer 4 port data
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22
Q

When reviewing the forwarding table, what does ‘ulst’ mean under the ‘Type’ header?

A

ulst indicates a list of unicast next hops.

A packet forwarded to this next hop goes to any next hop within the list

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23
Q
A
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24
Q

What is Filter-Based Forwarding? (FBF)

A

Filter-Based Forwarding (FBF) enables routers to forward traffic based on additional criteria, such as a packet’s source address.

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25
Q

What configuration tasks are required for Filter-Based Forwarding?

A
  • Creating a match filter - defined under [edit firewall]
  • Creating Routing Instances - defined under [edit routing-instances]
  • Creating a RIB group - defined under [edit routing-options]
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26
Q

What routing instance-type is used for FBF?

A

forwarding

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27
Q

Bob works at ABC Corp as a network administrator. Bob’s network consists of a router with two external links; ISP-A and ISP-B. In the current scenario the router looks only at the incoming packet’s destination address when determining the forwarding next-hop and forwards all connections to ISP-A.

How would Bob change so that all traffic sourced from 172.25.0.0/24 uses ISP-A and all traffic sourced from 172.25.1.0/24 uses ISP-B?

A

* Define a match filter based on source-address

  • Apply the match filter to the logical interface
  • create a routing-instance for each ISP
  • Configure the rib-group to share into the new routing instances
28
Q

What are the components of a Static Route?

A

next-hop [prefix discard reject] qualified-next-hop resolve

29
Q

What is Ethernet?

A

Family of LAN Specifications, standardized in IEEE 802.3 Uses Data Link Layer Technology to create LANs Shared medium a Single broadcast domain and collision domain Uniquely identifies all nodes on the LAN with a 48-bit MAC address

30
Q

What is bridging?

A

Segments a single collision domain Isolates the physical layer Learns and maintains the a forwarding table (bridge table) Performs intelligent forwarding decisions based on the bridge table Defined in IEEE 802.1D-2004

31
Q

What are the benefits of Bridging?

A

Divides a single-collision domain into multiple, smaller, bridged collision domains. Allows a mixed collection of interface types & speeds to be logically grouped within the same bridge LAN

32
Q

What are the mechanisms used by Bridging?

A

Learning - Learns MAC Addresses and associated ports Forwarding: Forwards packets out the proper egress interface toward the destination Flooding: Replicates packets out other ports for unknown destination MAC addresses Filtering: Limits traffic to it’s associated network segment Aging: Ensures bridge table entries are current

33
Q

Describe the following Bridge mechanic: Forwarding

A

Delivers traffic, passing it from an incoming interface to an outgoing interface that least to or toward a destination Steps: 1. Switch consults the bridge table for Destination MAC comparison 2. If found, forwards traffic based on MAC Address in bridge table 3. If not found, flood out all but port on which traffic was received

34
Q

Describe the following Bridging mechanic: Flooding

A

A transparent mechanism to deliver packets to unknown MAC addresses when there is no bridging entry found, or if packets received are broadcast or multicast. The MAC is learned and recorded based upon the response and the interface on which the response is received.

35
Q

Describe the following Bridging mechanic: Flooding

A

The filtering mechanism limits traffic to its associated network segment or VLAN. Filtering prevents the switch from forwarding traffic from one network segment to another

36
Q

Define the following Bridge mechanism: Aging

A

Used to ensure that only active MAC address entries are in the bridge table. The bridge table maintains a time-stamp of the last time a MAC address was seen and a timer is configured to drop MAC addresses which have not been seen in a specified amount of time.

37
Q

Define a VLAN

A

A collection of network nodes that are logically grouped together to form separate broadcast domains

38
Q

Layer 2 Bridging or VLANs

What are the two switch port modes?

A

Access Mode Trunk Mode

39
Q

Describe the function of the Access Switch port mode

A

Connects to network devices such as desktop computers, IP phones, printers, or file servers. Typically belong to a single VLAN and tx/rx untagged Ethernet frames.

40
Q

Describe the function of trunk switch port mode

A

Typically connects to another switch or to a customer edge router. Handles traffic for multiple VLANs, multiplexing traffic for all configured VLANs over the same physical connection. Separating the traffic by tagging it with the appropriate VLAN ID. Can also carry untagged traffic if when ‘native-vlan-id’ is used Control traffic is untagged

41
Q

Describe an Ethernet Frame (802.1Q) tag components

A

Tag Protocol Identifier (TPID) Priority Canonical Format Indicator (CFI) Unique VLAN Identifier (VID)

42
Q

What is MVRP?

A

An application protocol of MRP (Multiple Registration Protocol) and is defined in the IEEE 802.1ak standard. Performs the same functions as Generic Attribute Registration Protocol (GARP) but overcomes bandwidth usage and convergence time limitations.

43
Q

Describe how MVRP works

A

MVRP sends Protocol Data Units (PDU) to send VLAN registration information including the current VLAN membership details PDUs are shared with all participating switches

44
Q

What is an IRB interface?

A

Integrated Routing and Bridging interface A logical layer 3 interface used as an IP gateway for a VLAN.

45
Q

How are firewall filters are evaluated?

A

Single-Term filters: If all conditions match move to then statement, else discard Multiple-Term (terms evaluated sequentially): operates as an OR statement, only discarding if no filter is matched Filter chains are concatenated logically into a single filter

46
Q

What is the purpose of a bridge domain on an MX Series router?

A

A bridge domain allows you to specify which VLANs will be used for Layer 2 switching

47
Q

How does a bridge handle multicast Ethernet frames?

A

A bridge generally forwards multicast frames out of every interface except for the one from which they were received

48
Q

What is the purpose of the IRB interface?

A

An IRB interface eliminates the need for an external router to route between VLANs. It acts as an IP gateway for the hosts attached to a VLAN

49
Q

Which match condition is used in a Layer 2 firewall filter to match on 802.1p priority bits?

A

learn-vlan-1p-priority

50
Q

What are the types or routing instances?

A

Virtual-router Virtual-switch

51
Q

What is the default interface table assignment?

A

Layer 3 Interfaces associate with inet.0 Layer 2 interfaces associate with the default-switch virtual switch

52
Q

What will be the outcome when a trunk port is not bound to a virtual-switch?

A

A loop will be introduced into the topology

53
Q

Why does Spanning Tree Protocol not work on virtual-switches?

A

Virtual switches share the MAC address of the physical switch

54
Q

How do Logical Systems (LSYSs) differ from routing instances?

A

Each LSYS has its own discrete admin domain, logical interfaces, routing instances, security policies, and other routing and security features.

55
Q

How many LSYSs can be configured at any one time?

A

A Maximum of 15

56
Q

Limitations of LSYS

A

Does not support Non-Stop Routing (NSR), non-stop bridging (NSB), and unified in-service software upgraded (However graceful restart IS supported)

57
Q

What are the 5 OSPF Packet Types?

A
  • Type 1: Hello
  • Type 2: Database Description
  • Type 3: Link-state request
  • Type 4: Link State Update
  • Type 5: Link-State Acknowledgement
58
Q

What is the function of the OSPF Type 1 LSA?

A
  • Hello Packet
  • Multicast Hello packets are used to establish and maintain OSPF neighbor relationships
59
Q

What is the function of the OSPF Type 2 LSA?

A
  • Database Description
  • Exchanged during adjacency to determine which router oversees the database exchange
    • Describe the contents of the link-state database
    • Consist of the OSPF Header, a Sequence Number, and LSA Headers
60
Q

How is the primary OSPF Router decided for a Database synchronization process?

A

The router with the highest router ID is selected to be in charge of the db synchronization process.

61
Q

What are the seven possible OSPF adjacency states?

A
  • Down
  • Init
  • 2Way
  • ExStart
  • Exchange
  • Loading
  • Full
62
Q

Explain the difference between an OSPF Neighbor and OSPF Adjacency

A
  • Adjacency is formed between two OSPF DRs to minimize traffic overhead
  • Adjacent OSPF routers share full Link-State Databases
  • Neighors know about each other, and can agree on certain parameters.
63
Q

What are the different types of OSPF Areas?

A
  • Backbone Area
  • Stub Area
  • Not so Stubby Area (NSSA)
  • Totally stubby area
64
Q

What are the differences between the OSPF stub areas?

A
  • Stub area: Does not carry external routers, and cannot contain ASBRs
  • Totally Stubby: Stub area that receives only a default route from the backbone
  • Not-So-Stubby area: Accepts external routes to be advertised within the area, but not received from another area.
65
Q
A

JNCIS-SP (4 decks)

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