""Robert D. Cluett"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > I am just getting into BGP and I understand it like this. An update can > carry all or some of the attributes with it which define the route to the > destination. There is a pecking order of what attributes determine what > route will be utilized. So if you were to look inside of a BGP update > packet you will see the mandatory attributes being AS-PATH, Next-Hop and > Orign (these are mandatory so they will alway be in the packet). The > discretionary and optional attributes may or may not be there. When > updating the BGP table these attributes are analyzed and then the route is > chosen to the destination. Remember that a router will send an update > packet to you. It is adding the AS that is passes through to the AS_PATH > field. This is one of the requirements in order to have a route to a > destination. Next_Hop (IP Address) is also a requirement so you know where > to go next. Origin defines what AS this update came from.
Actually, this in incorrect. The Origin attribute has nothing to do with what AS the route comes from. It has to do with how the route in question was passed into BGP. The best reference for path-attributes is still, the one and only, RFC1771. Anybody who really really wants to understand BGP must read this. > I re-read the > chapter 3 times and have it cold now! I typically re-read and it clears > everything up that I missed. > > ""maine dude"" wrote in message > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > Hi I'm having problems on understanding how attributes work. I understand > > what they are there for but when questions come up I am unable to relate > the > > question to what I understand when I read the book. Are there any simpler > > guides available. I have the same problem with prefix-lists. -DJ > > > > > > > > --------------------------------- > > Get a bigger mailbox -- choose a size that fits your needs. > > > > http://uk.docs.yahoo.com/mail_storage.html Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=50321&t=50248 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
