From: Volkov, Dmitry (Toronto - BCE) (dmitry_volkov@xxxxxxxxx)
Date: Wed Aug 28 2002 - 21:53:02 GMT-3
Nick,
Can we say that by default (bgp deterministic-med is not enabled)
Metric(MED) is not compared between ANY (doesn't matter from the same AS or
not) routes with the same path lenghts ?
I.e. MED - is not taken into consideration in the
BGP best path selection alghorithm ? (by default) So forget about MED
completely until enable "bgp-deterministic-med" or "bgp
always-compare-med" ?
Looks like I missed it.
Also this sentence:
(MED is used in this comparison by default because the winners of each group
are now from different ASs - enabling bgp always-compare-med changes this
default behavior).
from http://www.cisco.com/warp/public/459/37.html
Is it mistake ?? Should I read (MED is NOT used in this comparision....)
because it doesn't compare MEDs from different ASs until "bgp
always-compare-med" is enabled ?
Thanks,
Dmitry
> -----Original Message-----
> From: Nick Shah [mailto:nshah@connect.com.au]
> Sent: Wednesday, August 28, 2002 7:36 PM
> To: Jon O'Nan; ccielab@groupstudy.com
> Subject: Re: deterministic med
>
>
> Jon
>
> I hope you have already read this paper..
> http://www.cisco.com/warp/customer/459/bgp-med.html
>
> regardless of that. I will list down the effect of these 2 commands.
>
> * By default (with none of these commands entered) MED is NOT
> compared when
> selecting the best path.
> * Turning on bgp deterministic-med, turns on the feature to
> compare MED,
> however it only compares MED, if prefix is received from same
> neighbor and
> the best man wins
> * Turning on bgp always-compare-med, starts comparing 'same
> prefix' recd.
> from 'different neighbors' and the best man wins
> * Turning on both of them may really not be required, but it basically
> compares if prefixes are recd. in groups of AS's (say same
> prefix from AS
> 200, via 2 neighbors, and same prefix from AS 100 via 1 neighbor).
>
> rgds
> Nick
> ----- Original Message -----
> From: "Jon O'Nan" <jononan@columbus.rr.com>
> To: <ccielab@groupstudy.com>
> Sent: Thursday, August 29, 2002 8:58 AM
> Subject: deterministic med
>
>
> > Am I correct that:
> >
> > bgp deterministic med - compares med within AS
> >
> > VS.
> >
> > bgp always-compare-med - compares med from another AS
> >
> >
> > Thanks
> > Jon
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