Solved: ATM PVP traffic problem

simone.barbarella · ‎04-30-2009

Hello all,

i'm currently using a Cisco 7206 NPE-G2 with a PA-A3 to terminate DSL customers. i have 6 VP configured with many VC's inside, one for each customer. I used the "atm pvp" configuration specifying the PCR with values given by our ISP. So all the VC's are UBR without particular parameters. We have also a contractualized SCR with the ISP on every VP.

On two of that VP's i have a strange problem: their traffic is well below half of the PCR (even below SCR) and customer reports that their DSL is very slow. If i change the PCR value, for example 3/4 or less of the total PCR the traffic increase and the customers benefit from it. When i put back to real PCR the traffic drops and stay low.

What's the issue with that? The ISP says that everything is ok by their side.

paolo bevilacqua · ‎05-04-2009

So it may be that someway you are exceeding some CR while it doesn't happen with a lower PCR on the PVP.

As mentioned above, PA-A3 doesn't support hierarchical shaping, for that you need to front-end an LS1010 that is able to do that.

View solution in original post

paolo bevilacqua · ‎05-03-2009

Hi,

The SP can have an actual PCR higher thatn what you (and they) may think. So when you raise your values, you become actually able to benefit from the true VC throughput.

Similarly, you could try taking off the PVP shaping to observe how service is affected.

Consider, the PA-A3 doesn't fully support hierarchical shaping of ATM, for that you would benefit of a fron-end LS1010 with an advanced processor.

On the other hand, it is not even said that you absolutely need.

ATM is a bit of black magic sometime, as proper investigation on cell rate issue require very expensive equipment to to properly diagnose.

simone.barbarella · ‎05-03-2009

The problem is exactly the opposite: one of that VP has a contractualized PCR of 30Mbit and 27Mbit of SCR. If i configure PVP with 30Mbit on the 7200 the traffic stays on 12-13Mbit and the dsl customers reports slowness on their connection. If i lower the PCR to, for example, 16Mbit, the traffic immediately go up from 12Mbit to 16 and stays there. If then i raise it to 20, it starts to drop again, maybe to 10Mbit then slowly return to 12-13. I'm figuring out if it's a PA-A3 issue (i have 3100 VC on 4096 max, with some VP with very large amount of customers) or it's a provider issue or simply a mismatch between policies. Is there any method to shape single VC's even with PVP configuration?

paolo bevilacqua · ‎05-04-2009

So it may be that someway you are exceeding some CR while it doesn't happen with a lower PCR on the PVP.

As mentioned above, PA-A3 doesn't support hierarchical shaping, for that you need to front-end an LS1010 that is able to do that.