[c-nsp] Segment Routing

[Phil Bedard]

If you have an existing network running LDP/6PE for years and aren’t looking to do much else other than support basic MPLS services, there isn’t a whole lot of incentive to move to SPRING.  At the end of the day SPRING is just another control-plane and piggybacks onto an existing routing protocols instead of running a separate protocol.  

Most of the interesting things with SPRING come from the fact you are using global deterministic labels, or at least indexes.  Using anycast SIDs you can easily point traffic through a transit area, to a specific peering location, or if you have a dual-plane network it’s easy to add a label to steer traffic to a specific plane.  

Right now there are still lots of RSVP-TE applications not supported by SPRING in a distributed network, like bandwidth reservations for instance.  I think most of those applications come over time, or things migrate to doing all of them using a centralized PCE, but it hasn’t happened yet.   There is definitely a strong movement towards it and is why you see full support from Juniper and Nokia now.   If I was building a greenfield network I would definitely use it instead of LDP.  

Phil

-----Original Message-----
From: cisco-nsp <cisco-nsp-bounces at puck.nether.net> on behalf of Aaron <aaron1 at gvtc.com>
Date: Tuesday, January 3, 2017 at 23:50
To: 'Mark Tees' <marktees at gmail.com>
Cc: <cisco-nsp at puck.nether.net>
Subject: Re: [c-nsp] Segment Routing

    Thanks Mark,
    
     
    
    Help me here…  what is the “worry” with LDP that you speak of.  I don’t see the worry in LDP… it seems to do its thing without much intervention from me at all.  About LDPv6, I’m assuming that ldpv6 is related to ipv6…. I’ve been testing 6VPE (ipv6 over top of mpls l3vpn) and it seems fine with my underlying ldp…so I’m not sure what to understand about that.
    
     
    
    As for the second point of TE… I guess since I’ve never done any MPLS-TE or RSVP-TE, I will have trouble seeing the benefit of SR over traditional RSVP-TE… but I will take note of your point.  So would you say that if I learn about RSVP-TE and what I can accomplish with it, that I should NOT move in that direction, but spend time deploying SR and then benefit from the easier TE ?  
    
     
    
    Thanks again Mark, 
    
     
    
    -Aaron
    
     
    
    From: Mark Tees [mailto:marktees at gmail.com] 
    Sent: Tuesday, January 3, 2017 10:42 PM
    To: Aaron <aaron1 at gvtc.com>
    Cc: Mohammad Khalil <eng_mssk at hotmail.com>; Patrick Cole <z at amused.net>; CiscoNSP List <CiscoNSP_list at hotmail.com>; cisco-nsp at puck.nether.net
    Subject: Re: [c-nsp] Segment Routing
    
     
    
    Two benefits I can think of:
    
     
    
     Label distribution without having to worry about LDP or LDPv6.
    
     
    
    Easy TE cases without having to worry about the state that comes with RSVP-TE.
    
    
    
    On Wednesday, 4 January 2017, Aaron <aaron1 at gvtc.com <mailto:aaron1 at gvtc.com> > wrote:
    
    I run an MPLS network for an ISP and have heard about SR/SPRING but I don't
    know much about it.
    
    What would you tell someone like me as to how I would benefit from SR/SPRING
    in my MPLS network ?   ...and if there isn't immediate benefit, are there
    inevitable long-term benefits that I could reap by moving towards a segment
    routed mpls network ?
    
    -Aaron
    
    
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    -- 
    Regards,
    
    Mark L. Tees
    
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