[c-nsp] Redistributed EIGRP Route Preferred over EBGP?

[Klaudiusz Staniek]

On 2011-04-18, at 20:24, Chris Mason wrote:

> > When EIGRP is redistributed to BGP the Cost Community is added to the prefix - it's basically FD for EIGRP.
> 
> This is where I think the problem is, but didn't believe that CC was
> compared until later down the BGP Path Selection Algorithm - by
> setting weight I preferred a path before that comparison was made:
> 
> As per CCO (http://www.cisco.com/en/US/docs/ios/12_0s/feature/guide/s_bgpcc.html):
> 
> The cost community attribute influences the BGP best path selection
> process at the point of insertion (POI). By default, the POI follows
> the IGP metric comparison.
> 
Cisco implements two types of POI as defined in http://tools.ietf.org/html/draft-retana-bgp-custom-decision-01
ABSOLUTE_VALUE and IGP_COST.

Cost:pre-bestpath means absolute value which is compared as FIRST step even before weight.

BTW:  This document is wrong: http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094431.shtml

It was different and correct just couple weeks ago because I was referring to it in some of my slides. This is not true that Cisco implements only IGP_COST!


> 
> 
> I will give it a try and see if it resolves the problem.
If you have simple topology you can also configure this: bgp bestpath cost-community ignore


Cheers,
klaus






€