Full BGP Table

[Nareshchandra R Paturi]

Hi My comany is planning get full bgp table from our providers we have mutliple egress providers in order to load balance we are looking for a full table from all of them what would be minumu requiremts we have all edges as 6500 with sup 720

is there any memory requrements that need to be upgraded ??

and is there any additional requiremnts to keep in mind.

[Giuseppe Larosa · Accepted solution]

Hello Nareshchandra,

given the high number of prefixes in a BGP full table (> 400,000) you need appropriate hardware to be able to support multiple BGP tables on C6500.

You need sup 720 3BXL or  RSP 720 3CXL focus on the XL versions of supervisors also for the newer versions of supervisors.

All DFCs installed in linecards have to be in line with the supervisor so DFC 3BXL, or DFC 3CXL and so on.

Standard supervisors and DFCs have not enough space to keep the resulting large CEF table.

The use of a wrong type of DFC can cause huge performance impact as many traffic flows would need to be processed in software (process switching fall back -> very high cpu usage and system can become unstable)

In addition to this, in the forums has been discussed, but there is no clear path to upgrade a sup720 3B to sup720 3BXL. It looks like it is not only a question of upgrading memory chips on SP and RP sub modules.

Hope to help

Giuseppe

[francisco_1 · Accepted solution]

good question and we had this issue a while ago and option were to upgrade to 720 3CXL and due to costs, we ended up taking partial routing table with a default routes. designed our routing policy to only accept routes up to 3 AS hops ands that reduced the size of the routing table on the sup 720 cards.

[profski]

Hy francisco

i know this is an old post und my english isn´t good, but can you give me an example 

howto only accept routes up to 3 AS hops filter

or an copy from your bgp config

thanks 

[Georg Pauwen]

Hello,

below are two ways to accomplish this:

ip as-path access-list 1 permit ^[0-9]+$
ip as-path access-list 1 permit ^[0-9]+_[0-9]+$
ip as-path access-list 1 permit ^[0-9]+_[0-9]+_[0-9]+$

!

neighbor x.x.x.x filter-list 1 in

ip as-path access-list 1 deny _.+_.+_.+_.+_
ip as-path access-list 1 permit .*

!

neighbor x.x.x.x filter-list 1 in

[Nareshchandra R Paturi]

Thx all

But

VS-S720-10G with

983008K/65536K bytes of memory.

isnt enough for the present day full routing tables??

[Giuseppe Larosa]

Hello Nareshchandra,

it is not enough because of the limit in CEF table size that is only 256,000 routes

see datasheet table -1

http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps9336/product_data_sheet0900aecd806ed759_ps708_Products_Data_Sheet.html

you would need PFC 3CXL

Hope to help

Giuseppe