Segment Routing

Tue May 22 15:14:13 UTC 2018

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.

On Tue, May 22, 2018, 16:19 Saku Ytti <saku at ytti.fi> wrote:

> Hey Steve,
>
> > the data plane behavior on LDP is swap oriented, while the data plane on
> SR
> > is pop oriented.  depending on the hardware capabilities in use this may
> > have (subtle) traffic engineering or diagnostic implications at a
> minimum.
> > folks will likely have to build tooling to address this.
>
> I think you're thinking of SR-TE, SR in normal LDP-like use case would be
> single
> egress label with swap on LSRs.
>
> Ingress PE would figure out label by using egress PE index as an
> offset to next-hop
> P's label range.
> Nexthop P would swap the label determining out label using same mechanism.
>
> I practice operators would configure same label range in every box, so
> swap would be
> from same label to same label. But that is purely due to operator
> configuration, and
> it's still swap.
>
> --
>   ++ytti
>