BGP announcement

[GilmarBrasilJunior]

Hello guys.

Thanks in advance for reading my question.

I'm kind new in the network world and I'm assuming a new role in my company, so I have new challenges.

I have attached a file with the scenario I'd like your help with.

Question:

On Router-1 we have BGP Active with different ISPs. On Router-2, that is in another site (backup DC), we have another ISP3 and we'd like to activate BGP in Router-2. 

May I activate a BGP session with ISP3, annoucing a lower weight and have BGP active in Router-3?

If it was possible, woud we have any problems on our main site?

I hope I was clear enough. 

Thank you guys.

[Giuseppe Larosa]

Hello @GilmarBrasilJunior ,

it really depends on the use the company wants to do of backup DC.

If backup DC must be used only when primary site fails you should advertise prefixes in R2 in such a way that they are never used when primary site is alive.

Depending on what prefixes your company owns ( for example several contiguous /24 public IP address blocks) the R2 can have BGP enabled safely by sending only an aggregate less specific route to ISP-3.

cisco weight is not advertisable to other BGP peers it is not a BGP attribute. However, it is clear what you mean.

If using a summary less specific route is not possible you could try to look at the use of your own BGP AS number prepending on R2 to make its advertisements less attractive.

Hope to help

Giuseppe

[GilmarBrasilJunior]

Hello @Giuseppe Larosa 

It is exactly as you mentioned, R2 (Backup DC) must be used only when our primary site is not available. 

I'm really new to BPG so I will reasearch and study a little bit to get to know how to do it (sending only an aggregate less specific route to ISP-3).

Thank you very much for your help!