7206VXR PA-GE interface problem

[gasparmenendez]

Hello, I have expanded my 7206VXR with a PA-GE card and a WS-G5483 gbic for copper. My problem is that the bandwidth in that interface is limited to 220 Mbps, don't know why. I know that bandwidth in that interface should be about 330 Mbps. Actually I connected the cable to another interface (g0/3) and reached the 330 Mbps very fast. Can anybody help me please???

Thanks in advance

BR.

[Joseph W. Doherty]

7206VXR populated with what?

[gasparmenendez]

I have connected a server through wich several clients are reaching internet.

[Joseph W. Doherty]

I mean, what's in every slot on the 7206.  You've replied to Gpauwen you've a -G1, but what's else is installed in the 7206?  I.e. what's in the PA slots and in the lowest slot (the I/O controller slot), on same side of the 7206?

BTW, where I'm going with my line of questioning, 7200 have hardware bandwidth limitations, with a -G1, you should check your bandwidth points.  See http://www.cisco.com/c/en/us/td/docs/routers/7200/configuration/7200_port_adapter_config_guidelines/config/3875In.html#wp1061412

[gasparmenendez]

here's a pic:

[Joseph W. Doherty]

Laugh - that works!

Ok, so the PA gig port is slower than 0/3, the latter being a port on the NSE?  If so, it could just be getting data to/from a PA just isn't as fast as a built-in NSE port allow.

From your photo, you have to gig PAs?  If so, how do they compare regarding performance?

[gasparmenendez]

Sorry for the delay, I appreciate your recommendation about laugh, that always works!!!!

Ok, the thing is that the PA gig port is precisely that, a GIG port, so theorically the bandwidth should be around 1Gbps, no the 220 it actually has. I think the difference is too much!! So something should be wrong.

About the other PA interface is working but with less bandwith, around 20 Mbps, so I can't compare...

Any other ideas???? this thing is driving me crazy

BR

[Joseph W. Doherty · Accepted solution]

Yea, it's a gig port, and the port should be able to transmit a single frame to/from the wire at gig, but how a gig port works with the rest of the device, depends much on the architecture of the device.  The difference you're seeing, between a PA gig port and an NPE gig port, could reflect a difference in the internal hardware architecture for getting data to/from the gig ports.

That said, there might be some configuration commands that might make a difference.  If so, you would probably need TAC for such advice.

I have read the PCI buses, on the 7200, are limited to 800 Mbps, but that's, I believe, the aggregate.  I.e. a gig duplex port would need 2 Gbps.

Still, 220 Mbps seems shy.

I'm wondering whether changing IOMEM and/or buffer and/or TX-ring settings might make any difference too.

Another difference, which you haven't be able to test, your two PA gig cards might achieve different performance because they are on different PCI buses.

Also keep in mind, a NPE-G1 can struggle with even one gig of bandwidth, let alone having multiple gig ports.

[gasparmenendez]

Thank you both friends...

Finally it seems to me a hardware limitation.

BR.

[Giuseppe Larosa · Accepted solution]

Hello Gaspar,

keep in mind that a C7200 is still a software based router with no ASIC chips to feed the port adapters.

I have seen similar performance issues on C7500 many years ago that caused us to move some services to the C12000 node that originally should be only P nodes.

With NPE-G1 you can remove the I/O controller because it has one built in. However, the performance issues on the two PCI buses that lead to the bandwidth points calculations are still there.

NPE-G1 has good performance on the built in GE ports onboard the NPE, but PA GE have less performance because it has to go trough the bottleneck of the PCI bus to communicate with the NPE ports.

If traffic enters an NPE port and exits from the PA GE,what you get may be normal.

Take in consideration the the NPE has a limitation in the total packet per seconds it can forward between its interfaces. So it depends from the mix of traffic with small packets / frames the pps may be reached with 220 Mbps out/in the PA GE.

I'm afraid you are facing architectural limitations of a Cisco router of great success, but not so new.

I have tested NPE G1 in 2006 to use the C7206VXR as a BGP route reflector server, it was ten years ago.

So I agree with Joseph you are facing device limitations.

Hope to help

Giuseppe

[Georg Pauwen]

Hello,

which NPE do you have installed in your 7206VXR ?

[gasparmenendez]

NPE-G1