bgp的问题

stl911

我想知道为什么在实施bgp的过程中还需要使用ibgp。
我觉得在一个as内部可以运行ospf rip等igp协议
然后把这些igp协议用ebgp的方法通告给bgp就好了，这样bgp不也就知道我as内部的路由了吗

blue_sky

看起来好象可行,不知试起来怎么样,只是你这样一个路由器就有一个以上的AS了,它既是IBGP,又是EBGP,可能对路由更新,聚合有点影响.

stl911

楼上这位兄弟能不能再说清楚一点，对于“只是你这样一个路由器就有一个以上的AS了,它既是IBGP,又是EBGP,可能对路由更新,聚合有点影响.”这句

blue_sky

自己看资料吧,搞清IBGP与EBGP的区别,及路由更新有什么不同.

yuhong

iBGP describes the peering between BGP neighbors in the same autonomous system(AS). You
use iBGP in transit autonomous systems. Transit autonomous systems forward traffic from one
AS to another AS. If you do not use iBGP in transit autonomous systems, the eBGP learned
routes are redistributed into an IGP and then redistributed into the BGP process in another
eBGP router. iBGP provides a better way to control the routes for the transit AS. With iBGP,
the external route information (attributes) are forwarded. iBGP is preferred over redistribution
with an IGP because the IGP does not understand AS paths and other BGP attributes.
Another use for iBGP is in large corporations where the IGP networks are too large to be supported
by an IGP, such as Open Shortest Path First (OSPF). Three independent IGPs are in
Figure 9-2: one for the Americas; one for Asia and Australia; and one for Europe, the Middle
East, and Africa. Routes are redistributed into an iBGP core.