cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
647
Views
0
Helpful
2
Replies

eBGP square or triangle?

andy.taylor
Level 1
Level 1

Hi,

Hopefully a simple eBGP question:

If I have 2 edge routers in an AS, and 2 edge routers in another AS is it best practices to have them in a square, or triangles?

By this I mean AS1 has router 1 and router 2 (running iBGP between them), and AS 2 has the same.

Is it best practice to have an eBGP peer between AS1 router 1 <-> AS2 router 1, and AS1 router 2 <-> AS2 router 2, or:

AS1 router 1 peering with AS2 router 1 and 2, and AS1 router 2 peering with AS2 router 1 and 2.

Either way, can somebody confirm the best practice and why?

Any help would be greatly appreciated.

2 Replies 2

cisco_lad2004
Level 5
Level 5

Andy

if layer ONE allows for redundancy, meaning R1-AS1 has 2 different links to R1&R2-AS2 then I would fully mesh.

if not, there are still some benefits.

I would set up 3 session on each router.

in this case traffic outboud, would always exit via external AS. so R1-AS1 >> R1 or R2 -AS2 (Unless u have manipulated IBGP attributes).

why would I fully mesh ?

1-Redundancy.

2-less hops, by meshing. u are allowing BGP to use less hops which sometimes customers like to see (unless MPLS is used)

HTH

Sam

Sam,

Many thanks. I deployed with multiple eEBP peers i.e. each router has 2 x eBGP and 1 x iBGP for redundancy and found faster convergence.

Many thanks for your reply, it's good to get validation :-)

All the very best,

Andy