From: Peng Zheng (zpnist@yahoo.com)
Date: Mon Apr 07 2003 - 03:54:38 GMT-3
But I implemented the same topology as that.
Sugarbush has three IP: 192.168.1.253 (to Stowe),
192.168.1.238 (to Diamond) and 192.168.1.249 (to
Burke), so BGP ID is 192.168.1.253.
And Diamond has three IPs too: 192.168.1.245 (to
Mammoth), 192.168.1.237 (to Sugarbush) and
192.168.1.241 to Burke), so its BGP ID is
192.168.1.245.
And I got the same route table on burke( preferred
Sugarbush).
--- Jonathan V Hays <jhays@jtan.com> wrote:
> You are referring to BGP Best Path Selection:
>
>
http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/
> ip_c/ipcprt2/1cdbgp.htm#1000898
>
> "12. If multipath is not enabled, prefer the route
> with the lowest IP
> address value for the BGP router ID.
> The router ID is usually the highest IP address on
> the router or the
> loopback (virtual) address, but might be
> implementation-specific. "
>
> I think you are mistaken on the IP addresses you
> gave since I don't see
> either 192.168.1.253 or 192.168.1.245 on page 191 of
> that book. Perhaps
> I have a different printing than you do. Anyway, I
> assume you are
> referring to Example 2-53 "Burke's BGP Table
> Contains Only the Aggregate
> Route" which shows 192.168.1.249 as having the best
> path instead of
> 192.168.1.241 (the lower IP address).
>
> Although the BGP router chosen as the Next Hop for
> this network happens
> to have the higher IP address value, you do not have
> enough information
> to say that it was the IP address value used by BGP
> to make that
> decision. There are eleven (11) previous steps in
> the BGP Best Path
> Selection hierarchy, any one of which takes
> precedence over this IP
> address criteria. The IP address criteria won't be
> used unless all of
> the other criteria are bypassed or are equal for
> both routers.
>
> Hope that helps.
>
>
>
>
> > -----Original Message-----
> > From: nobody@groupstudy.com
> [mailto:nobody@groupstudy.com] On
> > Behalf Of Peng Zheng
> > Sent: Sunday, April 06, 2003 10:21 PM
> > To: ccielab@groupstudy.com
> > Subject: Lowest BGP router ID prefered ?
> >
> >
> > Hi,
> >
> > It is said the route with lowest BGP router ID is
> > preferred. But I found the route with highest
> BGP
> > router ID os preferred.
> >
> > In Route TCP/IP V2, page 191, on Burke, the route
> with
> > BGP ID 192.168.1.253 is preferred to the route
> with
> > BGP ID 192.168.1.245.
> >
> > What's the reason?
> >
> > Thanks for help.
> >
> >
> >
> > __________________________________________________
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This archive was generated by hypermail 2.1.4 : Thu May 01 2003 - 13:35:48 GMT-3