[quagga-dev 11570] Re: [PATCH] BGP: add aspath_aggregate_mpath that preserves path length

Paul Jakma paul at jakma.org
Thu Oct 9 10:19:03 BST 2014

Hi Daniel,

On Wed, 8 Oct 2014, Daniel Walton wrote:

> DW# The ID doesn't matter as long as it is unique...no ID coordination 
> is required between two add-path capable speakers. The ID is just there 
> to make a NLRI unique so that advertising an additional NLRI doesn't 
> implicitly withdraw the previous advertisement.

Ah, indeed on the ID opaqueness thing. I must have been misremembering 

The selection mechanism I think could have interoperability / routing 
consistency issues I think. I'm curious why there isn't some capabilities 
defined to explicitly signal which path-grouping selection mechanism is 

Then, for BGP ECMP, what happens if a speaker wants to describe an ECMP 
path to a non-Add-Path speaker?

> DW# Cisco has it in ios and ios-xr, not sure about nx-OS. Juniper has 
> it. I've done RX support in quagga (will post the patch soon). TX 
> support in quagga is on our todo list.

Ah, great! :)

> DW# addpath is pretty stable at this point, hopefully the next draft 
> will be the last. It has been a very long process though, I submitted 
> the first copy of the draft 12 years ago. I have the revised text, just 
> need to sit down and submit it.

It has been a long path alright. :)

Paul Jakma	paul at jakma.org	@pjakma	Key ID: 64A2FF6A
Two can Live as Cheaply as One for Half as Long.
 		-- Howard Kandel

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