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Origin As of prefix IS local-as (private AS number)

Drawing1.jpg

 

Hi Dears i have this topoly but when announce prefix 1.1.1.0/24 allow by prefix-list on bgp connection private-As

(65444-by 65445) in As-path see valid as-number How fix this ?

The Origin As is private As-number

1 Accepted Solution

Accepted Solutions

Hello
So based on your topology and that url link you wish  - the base premise is for a single rtr 65445 (65444) to allow two different ebgp rtrs to peer towards it using different AS numbers

Also for any advertised prefixes to/from either ebgp peer, will be seen traversing the local/hidden ASN of that single rtr

Example
router bgp 65445
network 1.1.1.0 mask 255.255.255.0
neighbor 10.1.12.2 remote-as 65100
neighbor 10.1.13.3 remote-as 65101
neighbor 10.1.13.3 local-as 65444 no-prepend replace-as


local-as = allows ebgp rtr 65101 to peer with 65445 using AS65444
no-prepend = allows single rtr 65445 to remove or not prepend the local-asn 65444 towards rtr 65100 for any routes/prefixes advertised from 65101
replace-as = will replace and not show asn 65445 for any routse advertised to rtr 65101  so ONLY as 65444 is shown in all advertised prefixes 


Please rate and mark as an accepted solution if you have found any of the information provided useful.
This then could assist others on these forums to find a valuable answer and broadens the community’s global network.

Kind Regards
Paul

View solution in original post

4 Replies 4

Hello
Can you elaborate please--- i think I understand what you want to do but the topology isnt unclear.

RTR1 =AS65445
RTR2= AS65444  - 1.1.1.0/24


Please rate and mark as an accepted solution if you have found any of the information provided useful.
This then could assist others on these forums to find a valuable answer and broadens the community’s global network.

Kind Regards
Paul

My primary As is valid i create bgp session router B and A (by local-AS)

and filter by prefix-list announce 1.1.1.0/24 (announce by session local-AS)

now show ip bgp 1.1.1.0/24

show origin as is valid AS (must be private AS)

Prefix 1.1.1.0/24 Announce by router B

Hello
So based on your topology and that url link you wish  - the base premise is for a single rtr 65445 (65444) to allow two different ebgp rtrs to peer towards it using different AS numbers

Also for any advertised prefixes to/from either ebgp peer, will be seen traversing the local/hidden ASN of that single rtr

Example
router bgp 65445
network 1.1.1.0 mask 255.255.255.0
neighbor 10.1.12.2 remote-as 65100
neighbor 10.1.13.3 remote-as 65101
neighbor 10.1.13.3 local-as 65444 no-prepend replace-as


local-as = allows ebgp rtr 65101 to peer with 65445 using AS65444
no-prepend = allows single rtr 65445 to remove or not prepend the local-asn 65444 towards rtr 65100 for any routes/prefixes advertised from 65101
replace-as = will replace and not show asn 65445 for any routse advertised to rtr 65101  so ONLY as 65444 is shown in all advertised prefixes 


Please rate and mark as an accepted solution if you have found any of the information provided useful.
This then could assist others on these forums to find a valuable answer and broadens the community’s global network.

Kind Regards
Paul

I see this link but i dont find any configuration How do this by bgp 

https://bgplabs.net/session/3-localas/#start-the-lab