BGP attributes details

[ncnaveen_arasu]

Hi,

Please let me know what are the attributes available for BGP to influence outbound and inbound routing. And which are cisco proprietary attributes.

Thanks in advance,

Naveen

[cadet alain]

Hi,

there is only one Cisco proprietary attribute which is weight.

For outbound path selection you can use weight or Local Preference, both higher values win and default is zero for weight(excepted locally originated prefixes which have a weight of 32768) and 100 for local preference.

For inbound path selection you can use MED( lower wins) or AS_Path prepending or if your ISP supports it you can even use standard communities to tag routes and at the ISP these communities will get different local preference values.

Regards

Alain

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[Patrick Lloyd]

Take a look at packetlife and their BGP cheat sheet to get mroe information on the BGP attributes, how they're communicated, and how to do path influencing: http://media.packetlife.net/media/library/1/BGP.pdf

The Cisco BGP attributes page also tells of the specific Cisco proprietary attributes:

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094431.shtml