what's the meaning of BGP 'Only one route can be advertised in an Update message'?

[rookie R]

Hi!

When I was studying the BGP update message, someone says 'Only one route can be advertised in an Update message', but there are several NLRI in an update message capture. Are these two things different? Could someone help me with that, please?

[Giuseppe Larosa · Accepted solution]

Hello @rookie R ,

the meaning should be that you can send in a single Update packet only prefixes NLRIs that share the same path attributes like it happens in your packet capture.

for withdrawn prefixes this constraint is not present as the withdrawal section is just a list of prefixes to be removed without path attributes.

Be also aware that  BGP update optimization has been introduced from the time of writing of the book.

Hope to help

Giuseppe