[j-nsp] Segment Routing ( SPRING )

[Jesper Skriver]

> On 05 Mar 2016, at 16:41, Saku Ytti <saku at ytti.fi> wrote:
> 
> On 5 March 2016 at 15:22, Adam Vitkovsky <Adam.Vitkovsky at gamma.co.uk> wrote:
>>> (b) Are there any noticeable behavioral differences between SPRING and
>>> LDP implementations?
>>> 
>> Yes instead of label swap routers do label pop
> 
> This is not really a behavioural change. Traditionally this may occur
> also, due to say FRR, or really like VPN. On ingress you'll see top
> label is for you, so you pop it, then you'll do another lookup on what
> remains, might be VPN label pointing to customer might be another
> label pointing to another P..
> 
> Forwarding plane needs no update/change if not for lack of signalling
> capabilities, P router without SR support could transit SR packets.

Yes, SR with MPLS data plane can typically be used on any device supporting MPLS today. However they may be limitations on how many labels can be pushed, and thus especially on ingress into the network there may be limitations on what can be done. Similarly for load balancing there may be a limit on the depth of the label stack a device can traverse in order to find entropy labels or the IP payload used for load balancing decisions.

/Jesper