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Unfortunately, this article seems quite incorrect. It makes it look like iBGP and eBGP are different protocols while they are the same with a slightly different
by vbernat 5y ago
Unfortunately, this article seems quite incorrect. It makes it look like iBGP and eBGP are different protocols while they are the same with a slightly different set of rules. Notably, prefixes exchanged by iBGP definitely have an AS path (which can be empty, but usually it is not as most of the routes come from outside the AS). This is not the only error. The definition for iBGP/eBGP is incorrect too: iBGP let's two routers in the same AS exchange routes, while eBGP does the same for two routers in different AS.
- rayhaanj 5y agoTotally agree that the iBGP vs eBGP thing is very confusing, even in some vendor documentation there are some assumptions on what an internal vs external session should do instead of leaving it up to the user to decide how to operate. I get that this is probably for simplicity but it would be nice to give the user the full flexibility of the protocol.
- leoc 5y agoIf you're talking about the restriction that prevents the forwarding of routes in one iBGP connection and out another, I think that's a requirement of the standard rather than something vendors have imposed. Because iBGP hops don't prepend anything to the AS path, there would be no mechanism to prevent routing loops if multi-hop iBGP route forwarding were enabled. (I'm just a CCNP sprog, not an expert.)