RE: BGP Best Path Selection

Yeah, I was up for 36 hours...

Router id
Peer address

It what it wants... but router id would have to tie, for it to go to the last
one... PEER TO ADDRESS...

From: Divin Mathew John [mailto:divinjohn_at_gmail.com]
Sent: Thursday, June 04, 2009 5:25 AM
To: Jared Scrivener
Cc: Joseph L. Brunner; Cisco Fanatic; ccielab_at_groupstudy.com
Subject: Re: BGP Best Path Selection

Open, Oldest route (promotes stability :)
In, Lowest peer ID
Iowa, Lowest router id (obviously this would probably imply two peering
sessions to the same neighbor somewhere)

It should be
Open, Oldest route (promotes stability :)
In, Lowest router id (obviously this would probably imply two peering sessions
to the same neighbor somewhere)
Iowa, Lowest peer ID

cisco Doc cd...
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094431.
shtml

1. Prefer the route that comes from the BGP router with the lowest router
ID.

The router ID is the highest IP address on the router, with preference given
to loopback addresses. Also, you can use the bgp router-id command to manually
set the router ID.

Note: If a path contains route reflector (RR) attributes, the originator ID is
substituted for the router ID in the path selection process.

2. If the originator or router ID is the same for multiple paths, prefer
the path with the minimum cluster list length.

This is only present in BGP RR environments. It allows clients to peer with
RRs or clients in other clusters. In this scenario, the client must be aware
of the RR-specific BGP attribute.

3. Prefer the path that comes from the lowest neighbor address.

This address is the IP address that is used in the BGP neighbor configuration.
The address corresponds to the remote peer that is used in the TCP connection
with the local router.

Thanking You

Yours Sincerely

Divin Mathew John
divinjohn_at_gmail.com<mailto:divinjohn_at_gmail.com>
divin_at_dide3d.com<mailto:divin_at_dide3d.com>
http://www.dide3d.com
+91 9945430983
+91 9846697191
+974 5008916
PGP PUBLIC KEY BLOCK @ http://www.dide3d.com/divin_Public_PGP_key.txt
Sent from Bangalore, KA, India
On Thu, Jun 4, 2009 at 1:48 PM, Jared Scrivener
<jscrivener_at_ipexpert.com<mailto:jscrivener_at_ipexpert.com>> wrote:
Nice. That's the best one I've seen yet, Joe. I think I'm about to borrow it
for my classes.

Cheers,

Jared Scrivener CCIE3 #16983 (R&S, Security, SP), CISSP
Sr. Technical Instructor - IPexpert, Inc.
URL: http://www.IPexpert.com
Telephone: +1.810.326.1444
Fax: +1.810.454.0130
Mailto: jscrivener_at_ipexpert.com<mailto:jscrivener_at_ipexpert.com>

On 6/4/09 2:52 AM, "Joseph L. Brunner"
<joe_at_affirmedsystems.com<mailto:joe_at_affirmedsystems.com>> wrote:

> HERE IS AGAIN YURI
>
> Nobody, Next hop if unreachable, don't consider
> Wants, Weight Largest preferred
> Perot, Preference highest preferred
> Running, Route originated by BGP on this router
> Again, AS-Path, Shortest length is best
> Only, Origin, where I > E > ?
> Modern, Med (metric) prefer the Lowest MED, amongst paths. Know the med
> commands too and how they work!!!
> Economic, External over internal. This often leads to EBGP routes becoming
the
> best route
> Conservatives, Closest IGP neighbor, where closest would have the lowest
> routing metric (interesting one here be careful!!!)
> Open, Oldest route (promotes stability :)
> In, Lowest peer ID
> Iowa, Lowest router id (obviously this would probably imply two peering
> sessions to the same neighbor somewhere)
>
>
> -Joe
>
> -----Original Message-----
> From: nobody_at_groupstudy.com<mailto:nobody_at_groupstudy.com>
[mailto:nobody_at_groupstudy.com<mailto:nobody_at_groupstudy.com>] On Behalf Of
Cisco
> Fanatic
> Sent: Wednesday, June 03, 2009 3:59 PM
> To: ccielab_at_groupstudy.com<mailto:ccielab_at_groupstudy.com>
> Subject: BGP Best Path Selection
>
> All,
>
> Just was wondering if someone has a slang to remember BGP Best Path
Selection
> process?
>
> -Yuri
>
> _________________________________________________________________
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Received on Thu Jun 04 2009 - 08:49:48 ART