[j-nsp] Segment Routing Real World Deployment (was: VPC mc-lag)

[Mark Tinka]

On 5/Jul/18 10:15, James Bensley wrote:

>
> If you get any feedback you can publicly share I'm all ears!

Will do.

I'm currently working on getting those that have deployed it in the wild
to do a preso at an upcoming conference.


> As far as a greenfield deployment goes I'm fairly convinced that SR
> would be a good idea now, it would future proof that deployment and
> for our use case it does actually bring some benefits.

If you are deploying greenfield, then you have a good opportunity here
to go with SR.

In our case, we have different boxes from Cisco, each with varying
support for SR. This makes things very tricky, and then we need to also
throw in our Juniper gear. For me, the potential pain isn't worth the
hassle, as we are not suffering in any way that makes the move to SR
overly compelling.


> - Go IPv6 native: If using ISIS as the IGP we should be able to go
> IPv4 free (untested and I haven't research that much!).

For me, this is the #1 use-case I was going for; to be able to natively
forward IPv6 packets inside MPLS, and remove BGPv6 from within my core.

I had a discussion about this with Saku on NANOG:

    http://seclists.org/nanog/2018/May/257

Where we left things was that while the spec allows for signaling of
IPv6 in the IGP, there is no clear definition and/or implementation of
MPLSv6 in the data plane today.

For me, I don't really care whether I get MPLSv6 via LDPv6 or SR. For
the moment, LDPv6 has varying support within Cisco, so it's currently
not a migration path. SR support for MPLSv6 is unknown at the moment,
and certainly not a priority either, which leaves me with no immediate
appetite for SR.


> - Remove LACP from the network: SR has some nice ECMP features, I'm
> not going to start an ECMP vs LAG discussion (war?) but ECMP means we
> don't need LACP which again is one less protocol for inter-op testing,
> less to configure, less to support etc.It also keeps our p-t-p links
> all they same instead of two kinds, p-t-p L3 or LAG bundle (also fewer
> config templates).

I feel your pain.

As a matter of course, we stopped using LACP for IP/MPLS backbone links.
We rely on ECMP, until it makes sense to move a circuit to 100Gbps.

Mark.