CCNP Route Flashcards
1
Q
Routing Protocols common in WAN
A
RIP, OSPF, EIGRP
2
Q
Routing Protocols common to Internet
A
BGP
3
Q
What factors affects which protocol you would choose
A
Availability Vendor interoperability IT Staff Familiarity Speed of Convergence Capability to preform summarazation Interior or Exterior Routing Type of Protocol How it Advertises, stores and receives info
4
Q
Distance Vector Attributes
A
Sends full copy of routing table to neighbor
- inefficient
- slow convergence
- potential routing loops
5
Q
Solution to Routing loops
A
Split horizon
Poison reverse
6
Q
What does AS stand for
A
Autonomous system
7
Q
Distance Vector Protocols
A
RIP
EIGRP
8
Q
RIP Attributes
A
Hop count
Versions RIPv1, RIPv2, RIPng(next gen)
9
Q
RIPv2 Attributes
A
Supports variable-length subnet masks
Uses multicast NOT broadcast -224.0.0.9
10
Q
EIGRP Attributes
A
Does NOT send entire IP routing table
Uses triggered updates
Quick Convergence
11
Q
EIGRP Metrics/ K Values
A
Minimum Bandwidth* Cumulative Delay* Reliability Load MTU
12
Q
What Algorithm does EIGRP use
A
DUAL or Diffusing Update Algorithm
13
Q
Path Vector Attributes
A
Exact path packets take to reach the destination
Slow convergence
Very Scalable
Routing protocol of the Internet
BGP
14
Q
Example of Path Vector Protocols?
A
BGP
15
Q
BGP Versions
A
1-4
MP-BGP * supports routing of multi routed protocols
16
Q
What does Route Distribution allow?
A
A network to simultaneously support more than one routing protocol
17
Q
What was the predecessor to EIGRP
A
IGRP
18
Q
Network Architecture Types
A
Point to Point
Broadcast
NBMA
19
Q
NBMA (Non-Broadcast Multiaccess)
A
Does not support broadcast
Individual messages must be sent to each router
Issues with dynamic routing protocols
20
Q
NBMA Network Examples
A
ATM
Frame Relay
21
Q
Multicast IPv6 prefix
A
ff00::/8
22
Q
Anycast
A
Single IPv6 addresses -to multiple devices
23
Q
What traffic type does ARP use ?
A
ARP uses broadcast.
IPv6 cannot use ARP/Broadcast so it uses Network Discovery messages
24
Q
What is Asymmetric routing ?
A
Traffic leaves through one path and returns through a different path
25
ICMP Header Fields
Type - 1 byte
Code - 1 byte
Checksum - 2 byte
Rest of Header - 4 byte
26
TCP Sliding Window
Where the window size begins with one segment. If there is a successful acknowledgment of that one segment (that is, the receiver sends an ACK asking for the next segment), the window size doubles to two segments
27
Link State Protocols
OSPF
| IS-IS
28
Link State Attributes
* Builds a topological map of the network
* Routers send LSA's
* Exchanges full routing info only at initially forming an adjacency ******Then updated in response to changes
* Shorter convergence times
29
Common approaches to routing migration
```
* AD (Administrative Distance)
new routing protocols should be higher than the
exiting
*Route Distribution
cut over one network at a time
```
30
When migrating from RPVST to RPVST+ what needs to be removes?
UplinkFast
| BackboneFast
31
IPv6 Migration Consideration
*Check equipment for IPv6 compatibility
*Run IPv4 and IPv6 concurrently
*Check the ISP's IPv6 support
*Configure NAT64
* Allows IPv6 addresses to be translated to IPv4
addresses
*Not scalable
*Use NPTv6
*Send IPv6 traffic over an IPv6-over-IPv4 tunnel
32
VRF - Virtual Routing & Forwarding
*Allows a single router to run multiple virtual router instances
○ It router has its own configuration and its
own routing process
*Segments networks and isolates paths as needed
*Can use overlapping address spaces in different VR
33
EVN - Easy Virtual Networking
Same as VRF with more features
34
VNET - Virtual network trunk
| EVN
○ Carriers traffic for each virtual network and eliminates
the need to manually configure a sub-interface
○ Traffic tagged with VNET tag
○ Connects to switch via trunk link
* Route Replication
35
Route Replication
| EVN
○ When virtual networks need to be accessible by other virtual networks
Allows IP routes know to one virtual network to
be known by others
36
MPLS - Multiprotocol Label Switching
Makes forwarding decisions based on labels rather than IP addresses
32bit label
shim header
between layer 2 & layer 3
37
Layer 2 MPLS
Allows customer edge (CE) routers at different sites to form routing neighborhsips as if adjacent
38
Layer 3 MPLS
Allows a service providers edge (PE) router to establish peer relationships with customers edge (CE) router
39
Hybrid VPN
MPLS with tunnel based VPN's
MPLS over DMVPN
40
What should you consider in the deign with Hybrid VPN ?
Overhead - every time you add an encapsulation you are adding to the total header
41
Tunnel-Based Technologies
```
GRE
DMVPN
Multi point GRE
NHRP
IPSEC
```
42
GRE Generic Routing Protocol
Encapsulates nearly every type of data data out of a physical router interface
Any layer 3 protocol
Very flexible
No security
unless paired with IPSEC
43
DMVPN Dynamic Multipoint VPN
Allows VPN tunnels to be dynamically built and torn down between remote sites as needed
44
What is a common DMVPN Issue?
Flapping - connection keeps tearing down and establishing
Check the routing protocol
45
What other technologies does DMVPN require?
Multipoint GRE
NHRP
IPSEC
46
Multipoint GRE
Allows routers to supper multiple GRE tunnels on a single GRE interface
Dynamically form GRE tunnels by using NHRP to discover IP address of the device on the other end of the tunnel
47
NHRP - Next Hop Resolution Protocol
Router designated as the hub /server
All other routers the spoke/client
Spokes inform hub of physical and logical interfaces info
48
IPSEC
Can only protect unicast IP packets
Unless paired with GRE
Security features
IKE protocols
49
What are IPSEC's security features
```
Confidentiality
Integrity
Auth
Anti-replay
packets sent are not duplicates
```
50
What are the two IKE protocols and what is the difference?
AH - Authentication header
ESP -
ESP offers encryption
51
What are the IKE Protocol modes ?
Transport
| Tunnel
52
Tunnel Mode
Encapsulates the entire packet
53
Transport Mode
Users only the original packet header
| used mainly for client-to-site VPN
54
IPv6 Benefits
```
No broadcast
Only multicast to reach hosts
No need for NAT/PAT
More Addresses
Smaller routing tables
Fewer changes to Internet routing table
```
55
How does IPv6 addressing work ?
Public addresses group by geographic region
subdivided by ISP's inside that region
further subdivided by customer
56
IPv6 global unicast address
the 2000::/3 prefix as global unicast addresses.
| all unicast begins with 2 or 3
57
What does IPv6 use to dynamically learn addresses ?
Stateful DHCP
| Starless autoconfig
58
Steps to add Routes to IP routing table using EIGRP ?
Neighbor Discovery
Topology Exchange
Choosing Routes
59
Steps to learning best available EIGRP route ?
Establish neighbor relationships
Exchange EIGRP topology data with neighbors
Calculate the best IP route for each subnet based on
known topology data and add best routes to the
routing table
60
EIGRP and RTP (Reliable Transport Protocol)
Resends routing table updates that are lost in transit
| Confirms receipt
61
What is MTU used for in EIGRP ?
Used as a tie breaker if two paths have equal metrics but different MTU sizes
62
EIGRP default Hold Timers ?
```
Hello = 5
Hold = 15
```
63
EIGRP and BFD (Bi-Directional Forwarding)
Provides subsecond detection of a failure in IP connectivity between two neighboring routers
64
What EIGRP features must match to form neighborships?
```
Same subnet
○ As local router
Must not be passive on connected interface
AS number
Authentication
K-Values
```
65
What is the default K-Value for EIGRP ?
Metric weights 0 1 0 1 1 0
First value is ToS (Type of Service) and cannot be
changed
66
What does the EIGRP passive-interface command do ?
•Tells the router not to send any EIGRP messages on an interface
○ Still advertises the route
No neighbors possible on the interface
67
Why would you configure a static neighbor in EIGRP?
To reduce multicasts
NO dynamic neighbors can be discovered OR continue to work if already discovered
* Frame Relay
Only intended neighbors sent unicast
68
What are the EIGRP protocol messages
```
Hello
Update
Query
Reply
ACK
```
69
What protocols does EIGRP use in Query and Reply messages?
RTP - Reliable Transport Protocol
70
What does the Update EIGRP message include
Prefix
Prefix Length
Metrics
MTU and Hop count
71
What is EIGRPs multicast address
224.0.0.10
72
What does Split-Horizon do?
Limits the prefixes that EIGRP advertises out of an interface
73
What is Feasible Distance (FD) in EIGRP ?
Best route
Lowest metric
Successor
74
What is Reported Distance (RD)in EIGRP ?
Perspective next hop
| Feasible successor OR alternative route
75
What is an Offset List ?
Allows engineering to add value to calculate integer metrics for a given prefix
```
Defines value to be added to he KValues/Metroics
Match
Prefixes
Direction of Updates
Interface
Metric added to FD and RD
```
76
What is Convergence Manipulation used for ?
To make a router pick one route instead of another
77
What does Going Active mean ?
When a successor router is removed and no feasible successor is available, the router tries to discover whether any loop free alternatives exists to reach that prefix
78
What command would be use for load balancing in EIGRP ?
maximum-paths
variance multiplier
To overcome exact metric matches
79
What reduces the work load of Query messages in EIGRP for convergence purposes ?
Stub Routers
Route Summarization
80
Stub router features ?
Routers should not forward traffic between remote EIGRP
Non-Stub routers lean which routers are stub and do not send Query messages to those
81
Route Summarization Features ?
Summary routes include the prefix ad the
router immediately sends an EIGRP reply
and does not flood Query to other
neighbors
Keeps routing tables small
82
What commands do you use for Route Filtering ?
distribute-list (refers to ACL)
prefix list
route map
83
What are the features for IPv6 EIGRP ?
Advertises prefix lengths NOT subnets
No concept of classful networks / No route summarization
Does not require neighbors to be in the same subnet
84
What is the multicast address for IPv6 EIGRP
ff02::A
85
What are the features of Name EIGRP IPv6 ?
Consolidates IPv4 and IPv6 EIGRP configurations under a single hierarchical structure
Single virtual instance
Includes two address families. One for IPv4 and
one for IPv6
86
What are the steps of Link State for OSPF?
Neighbor Discovery
Topology Database Exchange
Route Computation
87
OSPF Features that must match?
```
Router ID
Stub Area Flag
Intervals/Timers
Subnet Mask
Auth
```
88
What OSPF metric does not have to match but can prevent data from being exchanged?
MTU
89
What type of information does the OSPF LSDB Include?
Router ID's
Interfaces/IP Adds/Masks/Subnets
List of routers reachable by each route on each interface
90
What Protocol is OSPF?
89
91
What is OSPFs multicast address?
224.0.0.5
92
What are the parts of a OSPF hierarchical design?
ABR
Backbone
Internal Router
93
Details about a ABR (Area Boarder Router)
Boundary between areas
Only generates Type 3 LSA's
Only advertises subnets between areas
94
OSPF Network Types
```
Broadcast
Point-to-Point
Loopback
Nonbroadcast (NBMA)
Point-to-Multipoint
Point-to-Multipoint nonbroadcast
```
95
Metro Eth/VPLAS (Virtual Private LAN Service)
Uses VLAN trunking with subinterfaces off a FA or GIG interface
Does NOT form OSPF neighborships with routes in the service providers network
Only between customer routers
96
What purpose does Virtual OSPF links serve?
Alternative to help networks meet backbone area designs without redesigning areas
Allows two ABRs that connect to the same nonbackbone area to form neighbortships
Acts as a virtual point-to-point connection
97
What are the different tables used in OSPF?
Neighbor table
Topology table
IP routing table
98
How does the OSPF Topology table work?
Sends individual LSA's
Copies those to the LSDB
Router applies the SPF algorithm to the
LSDB to determine the best path
99
Why would you limit the number of LSA's?
Protect the router memory
Router is unable to process LSA's
Cannot converge in a reasonable amount of
time
100
Type 1 LSA
Router - each routers has its own type 1 LSA/ It contains the RID and all interface IP addresses on that router that are in that area
101
Type 2 LSA
Network - represents a subnet in which a DR exists
102
Type 3 LSA
Summary - a subnet in another area
103
What are three options for metric tuning?
Change the reference bandwidth
Setting the interface bandwidth
Setting OSPF cost directly
104
Intra-areas
Uses pure link -state logic w/full topology information
| From Type 1 & 2 LSA's
105
Inter-areas
Uses distance vector logic
Takes it's know metric to reach the ABR and add the metric for that subnet as advertised by the ABR
NO additional SPD calculation required
106
What methods are used for Route Filtering?
Filtering would need to a happen with LSA transmissions
LSA Type 3 filtering using filter-list
Distribute list
107
Where in the OSPF hierarchy should route summarization be done?
ASBR andf ASR
108
What do defaults accomplish in OSPF?
Tells the ASBR to flood a default route into OSPF
109
What features were introduced in OSPFv2
Renames LSAs
Type 3 Inter-area prefix
Type 4 Inter-area rourer
New LSAs
Type 8 Link LSA
Type 9 Intra-area prefix
110
OSPFv3 Address Family configs accomplish what?
Combining IPv4 and IPv6
111
Stub/Stubby Area ?
Are shielded from external routes but receive information about networks that belong to other areas of the same OSPF domain
NO type 5 LSA's
112
Totally Stub Area?
Keep their LSDB-only information about routing within their area, plus the default route.
NO Type 3,4 or 5 LSA's
113
Not-So-Stubby Area ?
They prevent the flooding of AS-external link-state advertisements (LSAs) into NSSAs and instead rely on default routing to external destinations
Placed on edge of routing domain
Can import external routes
No type 5 LSA's
114
Why do you need route redistribution?
When one routing protocol needs to be distributed into a second routing protocol
115
What are the requirements for routing redistribution?
At least one working physical link with each routing domain
A working routing protocol config for each routing domain
An additional redistribution config for each routing protocol
116
Redistribution uses what table?
IP Routing Table
117
How is Redistribution manipulated?
Filtering and summarization
118
Redistribution tells other routers what information?
All routes in the routing table learned by the routing protocols
All connected routes of the interfaces on which that routing protocol is enabled
119
What does Redistribution from OSPF into EIGRP require>
Default metric settings
120
OSPF LSA 5 Includes?
Link-state ID
Subnet mask Advertising router Metric
External metric type
121
OSPF Redistributes what networks only?
Classful networks
NOT subnets
122
Redistribution from EIGRP into OSPF requires what command?
redistribute eigrp # subnets
123
What is a common Redistribution Issue?
Domain Loop - using multi redistribution points
124
How do you prevent Domain Loop?
Higher Metric
| AD-Administrative Distance
125
What is Packet Switching?
How a router takes packets arriving on an ingress interface and being sent out an appropriate egress interface
126
Modes of Packet Switching
Process Switching
Fast Switching
Cisco Express Forwarding (CEF)
127
Features of CEF Cisco Express Forwarding
Two tables in Data plan
| Does not require first packet to be switched
128
What two tables does CEF use
FIB
| Adjacency
129
Define Policy Based Routing
Override a routers natural destination based forwarding logic. Uses other parameters to forward on packets.
130
What does omitting the default parameter with policy based routing tell a router to do?
Try the Policy Based Route first, if it doesn't work, try to route as usual.
131
What are some other PBR features?
QoS
| IP SLA
132
Define VRF
Allows a single physical router to host multiple virtual routers, with those virtual routers logically isolated from one another, each with its own IP routing table.
133
What is a requirement to configure VRF-Lite?
Must configure a subinterface for each VRF on each router
134
Nat Limitations/Considerations
End to end connectivity
Issues w/Ipsec
PKI environment, digital certs could be incorrect
135
What is NVI - NAT Virtual Interface ?
Allows you to do NAT configurations without specifying an interface inside/outside
136
Addressing Hierarchy
```
• ICANN
○ IANNA
§Geographical regions
○ RIR - Regional Internet Registries
§ NIR - National Internet Registry
§ LIR - Local Internet Registries
®ISP's
○ IR - Internet Registry
gives IP's to end-
user organizations
```
137
What is the purpose of route aggregation?
The solution to keep up with the rare increase in the size of the IP routing tables.
138
What methods aid route aggregation?
Route summarization
| Prefix/length based on geography or ISP
139
Review Classful Network Assignments
Class A - 1 Network 10.0.0.0/8
Class B - 16 Networks 172.16.0.0/12
Class C- 256 Networks 192.168.0.0/16
140
Benefits of BGP Boarder Gateway Protocol
Best-path inside the global internet
More complex best-path algorithm
Flexibility to configure different settings that influence path selection
Does not require neighbors to be attached to the same subnet
Emphasis on scalability
Path Vector logic
141
AS_PATH key functions
# Choose the best route for a prefix based on the shortest AS_PATH
Prevent routing loops
142
When should you choose BGP as a routing protocol?
When you have at least two internet connections
You want to choose one outbound path over another path for a particular destination
143
Features of eBGP
Updates the AS_PATH PA
Forms neighbor relationships
Exchanging topology information
144
Requirements for eBGP neighbor relationships
Router ID's cannot be the same
Configuration must pass auth
Must be apart of a TCP connection
145
BGP Public/Private ASN's
1 - 64,495 Public
| 64,512 - 65,534 Private
146
What iBGP Behavior prevents Routing Loops?
When a router learns routes from an iBGP peer, that router does not advertise the same routes to another iBGP peer
147
Solutions to Routing Loops?
Run BGP on at least some of the routes internal to the enterprise
Redistribute BGP orutes into the IGP (not recommened)
148
Clearing BGP Peers Options
Hard
Soft in/out
In
Out
clear ip bgp *neighbor-id* "option"
149
BGP Best-Path Algorithm
N WLLA OMNI
0 - 8
150
Which Best-Path Algorithm attributes influence outbound routes?
W L A
151
Which Best-Path Algorithm attributes influence inbound routes?
M = MED
152
RIB failure
An event that occurs when the Routing Table Manager (RTM) attempts to add a route to the IP routing table, but a problem exists with the route that prevents RTM from adding the route.
153
Methods for assigning IPv6 Addresses
Manual Configuration
Stateless Address Config (SLAAC)
Stateless DHCPv6
○ Router needs more IPv6 information than just the address
Stateful DHCPv6
DHCPv6 Prefix Delegation
Assigns a collection of IPv6 networks to the router
154
3 Implicit instructions in a IPv6 ACL
permit icmp any any nd-na
permit icmp any any nd-ns
deny ipv6 any any
155
How are IPv6 ACL's different from IPv4?
ACLs are always extended and named
156
Common concerns for IPv6 Security
Neighbor Discovery can be used to launch man-in-the middle attacks
§ Similar to gratuitous ARP
IPv6 addresses are not concealed with NAT
157
BGP IPv6 Routing Design w/Single IPv4 Session Features?
Fewer neighborships are formed.
When sending IPv6 route information over the IPv4 BGP session, you need to create a route map to modify the Next-Hop BGP attribute.
158
BGP IPv6 Routing Design w/Dual IPv4 Sessions Features?
More neighborships must be configured.
You do not need to configure a route map to modify the Next-Hop BGP attribute.
159
MGP-BGP Features
Address Family Identifier AFI
Subsequent Address Family Identifier SAFI
Multiprotocol Reachable Network Layer Reachability Information
Multiprotocol Unreachable Network Layer Reachability Information
BGP Capability Advertisements
Backward compatible with BGP-4
160
Management Plane Security
```
SSH
Password Encryption
Username/Privilege/Password
Unicast Reverse-Path Forwarding
AAA
SNMP Config & Verification
NTP Authentication
```
161
What two types of ACL's extend router security?
Time Based ACL's
| Infrastructure ACL's
162
Two attributes of time-based key chains?
Accepted Lifetime
| Send Lifetime
163
Features of EIGRP Authentication
Helps prevent DoS attacks but no privacy
Attackers can join multicast subnet 224.0.0.10 and read packets
Prevents attackers from forming neighborships
164
EIGRP Auth command?
ip authen mode eigrp # md5
| ip authen key-chain eigrp # #####
165
OSPFv3 Auth Details?
Relies on IPSEC to provide authentication
| IPSEC can encrypt and authenticate
166
OSPF MD5 Auth command?
int fa0/0
ip ospf message-digest-ket md5 ####
router ospf 1
area # authen message-digest
167
BGP Auth command?
router bgp #
| neighbor x.x.x.x password ####
