BGP/Multi Home/Multiple sites

[alanfs]

Hi,

I run multiple pfsense (pairs) at multiple locations and I am moving to a BGP setup. All of the sites are connected via a ring to each other and to the internet. I have a /21 which I want to split between the sites (probably a /24 at each site).

I wanted some advise on the best way to set it up. Should I anounce the whole /21 from one of the pairs or should I anounce each of the /24 from each site?

Thanks in advance,
Alan

[gridrun]

@alanfs:

I wanted some advise on the best way to set it up. Should I anounce the whole /21 from one of the pairs or should I anounce each of the /24 from each site?

Announce the aggregate /21 and not the /24s!

Global routing tables are big enough already.

[Reiner030]

@alanfs:

I run multiple pfsense (pairs) at multiple locations and I am moving to a BGP setup. All of the sites are connected via a ring to each other and to the internet. I have a /21 which I want to split between the sites (probably a /24 at each site).

I wanted some advise on the best way to set it up. Should I anounce the whole /21 from one of the pairs or should I anounce each of the /24 from each site?

My ISP technican said me that you always have to announce your biggest network/AS … (we have also an /21 ;)).
If you later separate your networks then the separate network would be announced as /24 minimum and gets preference over your /21 announce.

We have split our actual used /24 in 8 parts... I announce additional /28 parts and our ISP routes them individually between our two buildings but announces only the /21 to public.
If your ISP is good he can it this for you, too ;). For instance you can set an COMMUNITY Tag for your /24 networks which your provider then can filter out for internal use only.

Bests

Reiner