At 01:10 PM 4/6/02, JohnZ wrote: >"IP connectivity has to be achieved via a protocol different from BGP; >otherwise, the session will be in a race condition. An example of a race >condition follows: neighbors can reach one another via some IGP, the BGP >session gets established, and the BGP updates get exchanged.
This must be referring to external BGP peers that are not directly connected and must rely on an IGP for connectivity? (EBGP multihop?) Normally BGP peers are on a LAN or WAN and can reach each other directly, simply with IP and TCP. I know that's not your question, but I thought it was worth mentioning that the example is kind of a weird situation. > The IGP >connection goes away for some reason, but still the BGP TCP session is up >because neighbors can still reach each other via BGP. Eventually the session >will go down because the BGP session cannot depend on BGP itself for >neighbor reachability" > >Wouldn't the same condition occur if reachability is acheived via a >different protocol. If the other protocol fails, yes. That's what he's saying. The race condition occurs when BGP must rely on BGP for connectivity. This should never happen. The routers can normally reach each other directly with TCP/IP or via an IGP. But if the BGP protocol had been written such that BGP depended on BGP, that's a race condition. It's also a race condition when the other protocol fails and BGP is once again depending on BGP. I hope that makes sense. Priscilla >If the route becomes unreachable then BGP conectivity >will still be lost.What's the advantage of making sure that "race condition" >is avoided. > > > >Thanks. > >JZ ________________________ Priscilla Oppenheimer http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=40713&t=40690 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
