Routing

Hi,

Please assist and help me with this scenario.

Currently i have 2 bgp peering to my router (old router). I am having new router at new site but at the moment dont have any new peering partner. My question.

1. can i divert one of my bgp peering from old router to new router for bgp testing only for a week?

2. after 1 week test i will normalized back the peering to old router.

3. any impact and does it give big problem to the existing network.

Actually my new upstream at new site will only be connected by Jun 2011 but i cant wait and need to test the router before end of april and thats the reason i have to use one of my existing peering.

FYI..both router will be connected each other and run bgp. 

Please.

Thank you.

chenoi

Hi,

Any body have gone through the same scenario? Please do assist me, need to get some info first before proceed further. 

Thank you for your input and suggestion.

Hi,

I'll attach a picture that hopefully describes your case.(see attach)

If I understood properly, you want to move peering with AS65003 from C1(Old router) to C2(New router) and you have already create an iBGP session between C1 and C2.

It'll work but you'll have to take the following into consideration:

1. If you have only 2 BGP speakers in your network(C1 and C2) it'll work fine, but if you have more speakers (like C3, C4...), you'll have to create from each one an iBGP session to the new router, or to do so using Route-Reflector.

2. You have to analyze the AS path received form both upstream because you can end-up using only B1 for outbound traffic because of shorter IGP cost calculated at C3 to C1 for prefixes with the same attributes from upstream. To overcome this you'll have to manipulate some of the BGP attributes, for example local-pref at C2...

Hi Dipapana,

If I understood properly, you want to move peering with AS65003 from C1(Old router) to C2(New router) and you have already create an iBGP session between C1 and C2.

--Yes i am going to move 1  peering from C1 to C2 but this will only be temporary migration till new upstream ready (3rd upstream ready for connection , Jun 2011). Then i will move back to C1. My concern is there any impact to the network (down/flap or take time to establish back the bgp session, etc) when the migration took place from C1 to C2 or C2 to C1.

--Yes ibgp session is created between C1 and C2.

It'll work but you'll have to take the following into consideration:

1. If you have only 2 BGP speakers in your network(C1 and C2) it'll work fine, but if you have more speakers (like C3, C4...), you'll have to create from each one an iBGP session to the new router, or to do so using Route-Reflector.

-- At the moment only 2 core router and run bgp. For future upgrade will do consider Route-Refltor, 

2. You have to analyze the AS path received form both upstream because you can end-up using only B1 for outbound traffic because of shorter IGP cost calculated at C3 to C1 for prefixes with the same attributes from upstream. To overcome this you'll have to manipulate some of the BGP attributes, for example local-pref at C2...

--Yes this will take into consideration.

Then should be no problem, just try to not get into troubles with BGP Route Dampening, do your work in a two step process...

Hi Dpapana,

Thank you sir for your information and suggestion.