[c-nsp] [j-nsp] Use cases for IntServ in MPLS backbones

[Mark Tinka]

On 2/Oct/18 15:38, adamv0025 at netconsultings.com wrote:

> Hi folks,
>
> I'm glad the thread spun up an interesting discussion but my original
> question was more around why would anyone prefer IntServ  to DiffServ in an
> RSVP-TE environment. 
> Personally I prefer RSVP-TE solely for TE purposes and QoS for QoS purposes,
> but there are always compromises if you haven't found one you're not looking
> hard enough, so here I am looking...

The way I looked at this when I began operating any kind of Internet
network back in the day was one of scale.

IntServ sparked the development of RSVP, whose idea was for clients to
signal the network and request for resources in order for their
applications to be guaranteed performance. Of course, in the real world,
it was soon obvious that your Windows laptop or your iPhone XS sending
RSVP messages to the network will not scale well.

So detaching the need for resources from any co-ordinated knowledge
between devices (clients and routers) about what those resources may be
in relation to each other leads to having no state in the backbone. This
became DiffServ, which I found more appealing than IntServ purely from
an administration perspective.

Of course, times changed and just as CLNS/CLNP were adapted to carry IP
NLRI, RSVP was adapted to convey MPLS signaling.

Mark.