The MPLS WG Archive

[David Charlap <david.charlap@marconi.com>]

Vipul Sharma wrote:
> 
> This has to do with Forward Equivalency Class (FEC). Since the 2
> services in ur PC have different QoS req. you will like them to be
> handled diff. in the Core network (perhaps to reflect their QoS). So
> you may have two LSP, one for each service. Each LSP corresponds to a
> FEC.

Correct.  If two packet flows are not supposed to be handled
identically, then they do not belong to the same FEC, even if they share
the same destination address.

> There is EXP bits in the MPLS Label that is there to convey the QoS
> info.

The EXP bits are for conveying DiffServ priority levels.  If you simply
want to prioritize best-effort traffic, and your switches can suport
E-LSPs, then this is the way to do it.

If you need actual QoS guarantees, or if your switches only support
L-LPSs, or if you want the two service levels to be routed
independantly, then you need to create a separate LSP for each service
level.  CR-LDP or RSVP-TE can be used for signalling the QoS
requirements for the two LSPs.

-- David