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bgp community number

cwangskr
Beginner
Beginner

when I do a sh ip bgp community ? I get the following on two routers.

route-views.oregon-ix.net>sh ip bgp community ?

aa:nn community number

local-AS Do not send outside local AS (well-known community)

no-advertise Do not advertise to any peer (well-known community)

no-export Do not export to next AS (well-known community)

| Output modifiers

<cr>

jo100-r5>sh ip bgp comm

jo100-r5>sh ip bgp community ?

<1-4294967295> community number

local-AS Do not send outside local AS (well-known community)

no-advertise Do not advertise to any peer (well-known community)

no-export Do not export to next AS (well-known community)

| Output modifiers

<cr>

one router has a community number <1-4294967295> and the other one has aa:nn

what is the difference? Is it IOS feature?

2 Accepted Solutions

Accepted Solutions

Richard Burts
Hall of Fame Guru Hall of Fame Guru
Hall of Fame Guru

Chandra

Yes it is an IOS feature. You can use the command ip bgp-community new-format to have the router format the community with the AS:value format.

HTH

Rick

HTH

Rick

View solution in original post

Pavel Bykov
Contributor
Contributor

Yes, this is an IOS feature. The first router has what is called a "new format" of BGP community. They are both 32 bit numbers, but in "new format" the community is specified in "aa:nn" where "aa" is your AS number and "nn" is an arbitrary number. It was created for practival purposes, because 65000:1 was easier to write and manage than for example 3128683542.

To turn on or off the new format feature use "ip bgp-community new-format" global configuration command.

Hope this helps.

Please rate all helpful posts.

View solution in original post

4 Replies 4

Richard Burts
Hall of Fame Guru Hall of Fame Guru
Hall of Fame Guru

Chandra

Yes it is an IOS feature. You can use the command ip bgp-community new-format to have the router format the community with the AS:value format.

HTH

Rick

HTH

Rick

Thanks, for the help

Pavel Bykov
Contributor
Contributor

Yes, this is an IOS feature. The first router has what is called a "new format" of BGP community. They are both 32 bit numbers, but in "new format" the community is specified in "aa:nn" where "aa" is your AS number and "nn" is an arbitrary number. It was created for practival purposes, because 65000:1 was easier to write and manage than for example 3128683542.

To turn on or off the new format feature use "ip bgp-community new-format" global configuration command.

Hope this helps.

Please rate all helpful posts.

Harold Ritter
Cisco Employee
Cisco Employee

Chandrathilaka,

The following command is configured on the first but not on the second router:

R1(config)#ip bgp ?

new-format select aa:nn format for BGP community

Regards,

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
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