Segment Routing

Tue May 22 15:48:48 UTC 2018

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