Segment Routing

Tue May 22 16:16:06 UTC 2018

Hi Saku gotcha and I see most config examples are RSVP/SR-TE like, where in
most of the networks I have come across basic LDP is more than acceptable.

On Tue, May 22, 2018, 17:48 Saku Ytti <saku at ytti.fi> wrote:

> Hey Matt,
>
> > I guess my point is why go through the extra config to program labels for
> > each box when LDP does it for you? Why loose potential visibility to
> network
> > traffic? Cisco sales and marketing is digging huge into the SR game for
> > enterprise and SDWAN like backbone networking. They are touting about the
> > whole industry changing, but I'm not seeing it anywhere in the large
> network
> > or provider space. Hench my original question why SR over LDP? Seems SR
> is a
> > lot of extra config to give you all the program options for white box
> like
> > networking, when basic LDP in a Cisco variant works just fine.
>
> There isn't inherently anything you need to configure in SR, it's all
> implementation detail.
> Juniper requires you configure your 'index', but just as well 'index'
> could be inferred from your loopback0 or router-id.
>
> And indeed in your configuration generation where you generate your
> router-id, you can use static method to turn router-id into unique
> index and configure it once.
> Or you could ask vendor to implement feature to auto-assign index.
>
> Much like some devices can auto-assign unique RD to VRF, some require
> operator to assign them. Entirely implementation detail, not a valid
> argument between protocols.
>
>
> The upside of SR to LDP
>   - removal of entire protocol
>   - full-mesh visibility
>   - guaranteed IGP+Label sync
>
> The amount of configuration needed to do SR like LDP should be less
> than LDP. Confusion may arise by looking at SR examples, as SR can
> also be used like RSVP, which indeed is far more complex use-case.
>
> --
>   ++ytti
>