BGP EBGP hops

[kswonnell]

Max EBGP hops is 255.

In a confederation AS, do the member AS numbers count as part of the AS path i.e. does the 255 max include confederation ASs ?

[donewald]

EBGP hops are counted by router hops, not AS hops. So, yes confederation AS members would be counted, as would any router.

Hope this helps,

Don

[kswonnell]

Let me rephrase the question:

The AS_Path attribute is up to 255 AS entries in length. If the AS path contains confederation AS numbers, are they counted as part of the 255 ?

[wkumari]

Yup, they are included when checking for the maximum lenght. Keep in mind that when the prefix leaves the confed, the confereration info is stripped. But yes, if you got a prefix with an AS path lenght of 253 and then the prefix transited 2 confederations, you would have to make the prefix as invalid.

[kswonnell]

Good answer Warren; thanks

[angelsoft]

From the IOS, IP routing command index, located at:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/ip_r/iprprt2/1rdbgp.htm#xtocid46

neighbor ebgp-multihop

To accept and attempt Border Gateway Protocol (BGP) connections to external peers residing on networks that are not directly connected, use the neighbor ebgp-multihop router configuration command. To return to the default, use the no form of this command.

neighbor {ip-address | peer-group-name} ebgp-multihop [ttl]

no neighbor {ip-address | peer-group-name} ebgp-multihop

Syntax Description

ip-address

IP address of the BGP-speaking neighbor.

peer-group-name

Name of a BGP peer group.

ttl

(Optional) Time-to-live in the range 1 to 255 hops.

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This means that the hops are actually the TTL of the IP packets.

If you don't know what TTL is, then you should be reading more TCP/IP

protocol suite books.

BR,

Zvezdelin

[kswonnell]

Thanks for the answer but you misunderstood my question. It wasn't about TTL or router hops, it was about ASs.