BGP Commands Flashcards

Including Route-Maps, Prefix-Lists, Dist-Lists, and Community-Lists

1
Q

Command to initialize the BGP Process?

A

Router(config)# router bgp as-number

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2
Q

Identify a BGP peer to establish a neighbor session

A

Router(config-router)# neighbor ip-address remote-as AS-number

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3
Q

Disable the automatic ipv4 address-family configuration mode in BGP.

A

Router(config-router)# no bgp default ipv4-unicast

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4
Q

Initialize a specific address-family and sub-address family configuration mode

A

Router(config-router)# address-family afi safi

Example:
Router(config-router)# address-family ipv6 unicast
Router(config-router-af)#

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5
Q

Make a BGP neighbor active for a specific address-family

A

Router(config-router-af)# neighbor ip-address activate

Note: from address-family configuration mode.

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6
Q

Advertise a network to BGP

A

Router(config-router)# network network mask subnet-mask [route-map route-map-name]

Example: Router(config-router)# network 10.9.8.0 mask 255.255.255.0 route-map RM_BGP_ROUTES

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7
Q

Configure a BGP aggregate IPv4 prefix (summary)

A

Router(config-router-af)# aggregate-address network subnet-mask [summary-only] [as-set]

Example: Router(config-router)# aggregate-address 10.9.8.0 255.255.255.0 summary-only as-set

NOTE: If bgp default ipv4-unicast is disabled, this is done in address-family config mode

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8
Q

Configure a BGP aggregate IPv6 prefix (summary)

A

Router(config-router-af)# aggregate-address prefix/prefix-length [summary-only] [as-set]

Example: Router(config-router)# aggregate-address 2001:db8:23:a/64 summary-only as-set

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9
Q

Display the contents of the BGP database

A

Router# show bgp afi safi [network] [detailed]

Example: Router# show bgp ipv4 unicast 10.9.8.0 detailed

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10
Q

Display a summary of the BGP table and neighbor peering sessions

A

Router# show bgp afi safi summary

Example: Router# show bgp ipv4 unicast summary

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11
Q

Display the negotiated BGP settings for a specified peer and the number of prefixes exchanged with that peer.

A

Router# show bgp afi safi neighbors ip-address

Example: Router# show bgp ipv4 unicast neighbors 10.4.4.1

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12
Q

Display the Adj-RIB-Out BGP table for a specific BGP neighbor

A

Router# show bgp afi safi neighbors ip-address advertised-routes

Example: Router# show bgp ipv4 unicast neighbors 10.4.4.1 advertised routes

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13
Q

What command is used on a BGP router to see the BGP peering state?

A

show tcp brief

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14
Q

What command might you need to ensure that an iBGP neighbor a reachable next hop address so the route will get installed to the Global routing table?

A

Router(config-router)# neighbor ip-address next-hop-self

NOTE: This is configured in address-family mode when bgp default ipv4-unicast is disabled

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15
Q

What command shows the BGP routing table?

A

show bgp afi safi

Example: show bgp ipv4 unicast

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16
Q

What command would you use to ‘reset’ all bgp neighbors? Why do you need to be careful about using that command?

A

Router# clear ip bgp *

This command will break all connections to BGP peers until the neighbor states are reestablished.

17
Q

What is the command you would use to see all the routes being sent out from the router you are on?

A

show bgp AFI SAFI neighbors ip-address advertised-routes

18
Q

For iBGP, when configuring neighbors using loopback addresses, what additional command is needed?

A

Router(config-router)# neighbor ip-address update-source loopback-#

Example: Router(config-router)# neighbor 5.5.5.5 update-source loopback0

19
Q

What is the command to create a route map? (Include the common options)

A

Router(config)# route-map NAME [permit | deny] [sequence-number]

NOTE: Best practice is to start sequence numbers at 10 and increase by increments of 10 similar to an access-list.

20
Q

What is the command to create an AS-Path Access List?

A

Router(config)# ip as-path access-list number {permit | deny} regular-expression-string

21
Q

What is the command to create a prefix-list?

A

Router(config)# {ip | ipv6} prefix-list NAME [seq sequence-num] {permit | deny} network-address/netmask [ge value] [le value]

Example: ip prefix-list deny FILTER_1 seq 10 deny 1.1.1.0/24 ge 32

22
Q

What is the command to create a BGP community-list for the purpose of conditional route matching?

A

Router(config)# ip community-list {1-500 | standard list-name | expanded list-name} {permit | deny} community-pattern

23
Q

From route-map config mode, what is the command to match on a BGP AS-Path?

A

Router(config-route-map)# match as-path acl-number

24
Q

From route-map config mode, what is the command to match on IP addresses that was set in an ACL?

A

Router(config-route-map)# match ip address {acl-number | acl-name}

25
Q

What is the command to redistribute routes from an iGP into BGP without any route filtering?

A

Router(config-router)# redistribute protocol-name [process-id]

NOTE: To redistribute from an IGP into BGP, this will be done in BGP configuration mode. When using address-families, it is done in the address-family config mode under the BGP process.

26
Q

What is the command to redistribute routes from an iGP into BGP using a route-map to filter the routes?

A

Router(config-router)# redistribute protocol-name [process-id] subnets route-map RM-NAME

NOTE: To redistribute from an IGP into BGP, this will be done in BGP configuration mode. When using address-families, it is done in the address-family config mode under the BGP process.

27
Q

What is the command to see a BGP rib-failure reason when seen in a routing table?

A

show bgp afi safi rib-failure

OR

show ip bgp rib-failure

28
Q

When trying to configure an eBGP peer using loopback addresses, what two commands may be needed to ensure the default TTL for eBGP does not prevent peering?

A

Router(config-router)# neighbor ip-address disable-connect-check
Router(config-router)# neighbor ip-address ebgp-multihop 1-255

29
Q

What is the command to create a Route Reflector?

A

Router(config-router-af)# neighbor ip-address route-reflector-client

NOTE: The command is done on the Route Reflector and in address-family config mode if applicable

30
Q

What are the commands to put a router into a BGP confederation?

A

Router(config)# router bgp Member-AS-number
Router(config-router)# bgp confederation identifier Main-AS-Number

31
Q

What command specifies the router will peer with another Member-AS other than its own?

A

Router(config-router)# bgp confederation peers Other-Member-AS

32
Q

Hard reset a BGP session with a peer

A

Router# clear bgp ipv4 unicast neighbor-ip

33
Q

Soft reset a BGP session with a peer

A

Router# clear bgp ipv4 unicast neighbor-ip [in | out | soft]

34
Q

Show bgp routes that only include a specific AS in the AS Path

A

Router# show bgp ipv4 unicast regexp regex-expression

35
Q

What is the command to create a Route Map?

A

Router(config)# route-map NAME {permit | deny} [sequence-num]

36
Q

Inside a Route Map, match ip on a prefix-list

A

Router(config-route-map)# match ip address prefix-list NAME

37
Q

Inside a Route Map, set the weight attribute

A

Router(config-route-map)# set weight value

38
Q

Enable IPv6 on a router (before configuring BGP for IPv6)

A

Router(config)# ipv6 unicast-routing

39
Q

Create an IPv6 neighbor (4 commands)

A

Router(config)# router bgp AS-number
Router(config-router)# neighbor ipv6-address remote-as AS-number
Router(config-router)# address-family ipv6 unicast
Router(config-router-af)# neighbor ipv6-address activate