How to analyze BGP routing problem?
Step one: BGP uses TCP as its transmission protocol (port 179), not same as the IGP routing protocol only can establish neighbor between the neighboring routers, it can establish neighbor when it can reach, therefore, first check whether the routers can reach each other. Step two: locate the failure router, and use show command to examine the information, e.g. interface list of BGP, neighbor table, routing table. Step three: probably analyze where the failure is through the collecting information, and then can analyze the packet interaction through debug, find out the reason. Q: The basic mentality of removing the failure of CE1. A: To diagnose the failure of channelized E1 line, must first confirm the problem is in some channel group or on the E1 line. If the problem is in a single channel group, there may be a latent interface problem. But if the problem is on E1 line or in all the channel groups, there may be a latent controller error, or can check whether the cable is a complete se
