Filter
Top Products
Setting Up Route Reflection Configuring BGP
page 4-40 OmniSwitch 6800/6850/9000 Advanced Routing Configuration Guide December 2007
Setting Up Route Reflection
BGP requires that all speakers in an autonomous system be fully meshed (i.e., each speaker must have a
peer connection to every other speaker in the AS) so that external routing information can be distributed to
all BGP speakers in an AS. However, fully meshed configurations are difficult to scale in large networks.
For this reason, BGP supports route reflection, a configuration in which one or more speakers—route
reflectors—handle intra-AS communication among all BGP speakers.
In a fully meshed BGP configuration, a BGP speaker that receives an external route must re-advertise the
route to all internal peers. In the illustration below, BGP speaker A receives a route from an external BGP
speaker and advertises it to both Speakers B and C in its autonomous system. Speakers B and C do not re-
advertise the route to each other so as to prevent a routing information loop.
Fully Meshed BGP Peers
In the above example, Speakers B and C do not re-advertise the external route they each received from
Speaker A. However, this fundamental routing rule is relaxed for BGP speakers that are route reflectors.
External BGP
Speaker
Speaker A
Speaker C
Speaker B
AS 100
Route