[j-nsp] BGP/MPLS Question MX Platform

Saku Ytti saku at ytti.fi
Wed Aug 3 12:01:13 EDT 2016


On 3 August 2016 at 18:49, Dean B <jnprlist at gmail.com> wrote:

Hey,

> Ok, that is going to show how inexperienced I am in MPLS/RSVP/etc. but what
> is the SPT you are referring to and what JunOS config elements does it

Shortest Path Tree (result of SPF algorithm). Essentially I'm talking
how you'll configure your IGP, will the expensive link be chosen as
result of IGP configuration or not.

> Speaking of QoS, might another way to solve this (assuming I could mark
> traffic eligible to discard) be to use use QoS on both sides of the
> high-cost link and just discard that marked traffic?  Then I could just let
> the existing ISIS/LDP stuff do it's thing.

Devices really don't support exactly this behaviour, not these days.
But if the link is say 1Gbps and you know you won't have more than
600Mbps of L2VPN. Then if you give L2VPN class/queue >=60% guarantee,
and rest for other traffic, then you'll never drop the L2VPN. Of
course you could do 98% L2VPN, 1% signalling and 1% all other traffic.
Bandwidth will be 'loaned' from class which is not using its
guarantee, so it'll work just fine.

-- 
  ++ytti


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