From: Howard C. Berkowitz (hcb@gettcomm.com)
Date: Sat Jul 05 2003 - 18:00:04 GMT-3
I come back to the mantra, "what problem are you trying to solve?"
There is a perfectly good intra-AS BGP attribute, not AS-path, that
affects route choice within an AS.
At 5:29 PM -0300 7/5/03, Carlos G Mendioroz wrote:
>Confeds ?
>
>Scott Morris wrote:
>>No, because iBGP doesn't ever add to the as-path. (Same AS, no need to
>>add)
>>
>>
>>
>>Scott
>>
>>-----Original Message-----
>>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
>>Jason Cash
>>Sent: Monday, June 30, 2003 11:40 PM
>>To: ccielab@groupstudy.com
>>Subject: AS Path prepend in IBGP
>>
>>
>>Is it possible to advertise an as-path prepend via IBGP? For some
>>reason, it doesn't seem to take:
>>
>>
>>R5(s0)---(s0)R2
>>
>>(e0)
>>
>>|
>>
>>(e0)
>>
>>R8
>>
>>
>>
>>R5
>>
>>interface Loopback0
>>
>> ip address 200.0.0.5 255.255.255.255
>>
>>!
>>
>>interface Loopback1
>>
>> ip address 172.32.1.1 255.255.255.0
>>
>>!
>>
>>router bgp 200
>>
>> no synchronization
>>
>> bgp log-neighbor-changes
>>
>> network 172.32.1.0 mask 255.255.255.0
>>
>> neighbor 200.0.0.2 remote-as 200
>>
>> neighbor 200.0.0.2 update-source Loopback0
>>
>> neighbor 200.0.0.2 route-map addas out
>>
>> neighbor 200.0.0.8 remote-as 8
>>
>> neighbor 200.0.0.8 ebgp-multihop 5
>>
>> neighbor 200.0.0.8 update-source Loopback0
>>
>> neighbor 200.0.0.8 timers 30 90
>>
>> neighbor 200.0.0.8 route-map addas out
>>
>> no auto-summary
>>
>>!
>>
>>access-list 5 permit 172.32.1.0 0.0.0.255
>>
>>!
>>
>>route-map addas permit 10
>>
>> match ip address 5
>>
>> set as-path prepend 500 501
>>
>>!
>>
>>route-map addas permit 20
>>
>>
>>
>>Below is the 'sh ip bgp' from both routers. R2 is iBGP and R8 is eBGP.
>>R8 shows the as-path prepend
>>
>>whereas R2 does not. What is the problem?
>>
>>
>>r2#sb
>>
>>BGP table version is 37, local router ID is 200.0.0.2
>>
>>Status codes: s suppressed, d damped, h history, * valid, > best, i -
>>internal
>>
>>Origin codes: i - IGP, e - EGP, ? - incomplete
>>
>>
>> Network Next Hop Metric LocPrf Weight Path
>>
>>*>i100.100.100.0/24 200.0.0.4 0 100 0 i
>>
>>*>i101.101.101.0/24 200.0.0.4 0 100 0 i
>>
>>*> 172.16.0.0/22 200.0.0.1 0 8888 i
>>
>>*>i172.32.1.0/24 200.0.0.5 0 100 0 i
>>
>>*>i200.200.200.0 200.0.0.6 0 100 0 i
>>
>>
>>
>>r8#sb
>>
>>BGP table version is 19, local router ID is 200.0.0.8
>>
>>Status codes: s suppressed, d damped, h history, * valid, > best, i -
>>internal
>>
>>Origin codes: i - IGP, e - EGP, ? - incomplete
>>
>>
>> Network Next Hop Metric LocPrf Weight Path
>>
>>*> 100.100.100.0/24 200.0.0.5 0 200 i
>>
>>*> 172.16.0.0/22 200.0.0.5 0 200 8888 i
>>
>>*> 172.32.1.0/24 200.0.0.5 0 0 200 500 501
>>i
>>
>>*> 200.200.200.0 200.0.0.5 0 200 i
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