[c-nsp] QoS Design Question

Tim Franklin tim at pelican.org
Thu Oct 18 11:28:26 EDT 2007

Hi Patrick,

On Thu, October 18, 2007 1:24 pm, Patrick Greene wrote:

> If I set a policy on the hub router to guarantee 10Mbps for LOB
> applications
> outbound towards the MPLS cloud and if I am telling my spoke router to
> guarantee 512Kbps for LOB application outbound towards the MPLS cloud then
> outbound I am all set.  However, for inbound LOB traffic on the spoke
> router
> the hub (set at 10Mbps) can send more than 512Kbps of LOB traffic and
> consume the T1 inbound.  On my spoke router, should I be setting my
> bandwidth guarantees inbound from the MPLS instead out towards the MPLS?

No, outbound - but outbound *everywhere*, CE and PE.

    10Mb LOB ->                    512K LOB ->
Hub ------------+----+ MPLS +----+------------ Spoke 1
    <- 10Mb LOB | PE |------| PE | <- 512K LOB
                +----+      |    |
                            |    | 512K LOB ->
                            |    |------------ Spoke 2
                            |    | <- 512K LOB

So the hub can send an aggregate 10Mb/s LOB traffic into the network, but
if it tries to send any more than 512Kb/s to any one spoke site, the
egress PE for that spoke will drop the excess traffic.

In the other direction, each spoke can try and send 512Kb/s LOB traffic,
but if 30 sites all try and do it at once, the PE where the hub connects
will drop the excess 5Mb/s.


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