[j-nsp] Subrate speed on GigE requiring CoS / Policer configuration

Chris Evans chrisccnpspam2 at gmail.com
Tue Oct 5 22:44:23 EDT 2010


I'm struggling to come up with a solution for my requirement.. Essentially
we are building a lab using GRE to link two sites over our enterprise
network. As this is a lab we want to limit the bandwidth that comes out of
the LAB to 15megabits, but using GigE for the physical connection on an m7i.
Essentially my first thought was implement a policer on the egress interface
limiting the maximum aggregate traffic to 15Mb, then implement a scheduler
on the GRE interface. I need to prioritize certain traffic leaving the lab
so I also want to use a scheduler to make sure that the voice traffic has
priority and has a 2Mb of traffic for example.

I want to limit my EF traffic to 2Mb, AF to 2Mb, NC to 500Kb and best effort
to 10.5Mb under signs of congestion within that 15Mb CIR.

1st issue.. It appears that you cannot implement schedulers on GRE
interfaces, as this isn't possible the next thought was to implement a
scheduler on the egress GigE using the copy TOS to header feature on the GRE
interface. Is certain hardware required to be able to do this? EIQ2 pic for
example?

2nd issue..As I'm trying to do a CIR of 15mb, I don't believe a scheduler
will work as the interface really is GigE there are no signs of congestion,
so the scheduler doesn't kick in. I've tried the extra parameters under the
transmit rate to use exact, rate-limit, etc.. nothing do what I expect it to
do. I'm not sure if the scheduler limiters are always active or only in
signs of congestion.


I've made it work by breaking out and creating individual policers per
forwarding class, however this isn't as sexy as I have to hard limit each
forwarding class within the aggregate 15Mb CIR. Thus it denies me the
possibility of the bandwidth being dynamic across all 4 forwarding classes.

Is this configuration even possible with Juniper devices?

Thanks

Chris


More information about the juniper-nsp mailing list