From: Jonathan V Hays (jhays@jtan.com)
Date: Mon Apr 07 2003 - 00:50:35 GMT-3
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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