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Re: Why doesn't BGP...
At 09:33 AM 11/9/96 -0800, Ed Morin wrote: >Look, I can do a "show interface" on any interface and see what speed >it's running at and if it's dropping packets. If BGP hears a route >on an interface that isn't dropping packets shouldn't _that_ route >be considered "best" all other things being equal (hop counts and >all)? You can't tell me the router doesn't know this information >because _I_ get the information from the router itself!! > >I understand about route instabilities, etc. All I'm talking about >here is a better "tie breaker" than ordinate numbers of IP addresses. > Ed, One major problem that you have overlooked is what happens when this wonderful automagic route protocol does exactly what you suggest? You have two wonderful paths to a wonderful location in a wonderful world. However, some wonderful traffic has wonderfully overwhelmed one of your links, and you have (not so wonderful) packet loss. Immediately your routing protocol senses this, and begins to prefer the other route. But a strange thing happens, the packet loss disappears on the first route and appears on the second and all of the sudden you have packet loss on the second link. Now I was not involved in the designing of the BGP (any rev level) specification, so the next bit of text is MHO of some of the thought process that may have gone into the development. Making something "fool-proof" tends to induce ignorance of the process and sloppy (if not negligent) engineering. BGP is NOT designed as the end all be all solution for networking. This still requires the human brain. I think perhaps the folks who designed BGP might have had this in mind. The phrase, "When all you have is a hammer, everything looks like a nail" comes to mind. Don't think of BGP as your hammer, it's a tool in a bag of tools. Of course there are always two necessary things one should know before using a tool: 1. What was the tool designed for? 2. What are all the features of the tool, that allows one to use it to it's fullest capability. And finally, I'm going to throw in my personal humble opinion... If you are having packet loss constantly on your network, and it's within your control, you need to re-engineer your network. If it's out of your control, you need to re-engineer your network to bring it within your control. <hops off soapbox> Chris A. Icide Nap.Net, L.L.C. - - - - - - - - - - - - - - - - -