C5 high CPU utilization - ipMapForwardingTask

[Jason_Wisniewsk]

I have a C5 that is giving me some grief. It is the core L3 for a medium sized network. There are 2 C5Gs and 1 C5K stacked.

Every so often when adding new hardware to the network the CPU goes nuts on the device and the only resolution is to randomly disconnect trunk ports to reset STP, essentially.

Today we added a new HP stack to the mix to act as an L2 for a VM network. This all went fine. The uplinks are trunked on both sides and we have a good link. I plugged in a VM server without issue. I then plugged in a simple DHCP device (APC PDU) and it completely brought down the network. CPU went to 95% and brought down pretty much all traffic. The process breakdown is below:

Total CPU Utilization:
Switch CPU 5 sec 1 min 5 min
-------------------------------------------------
3 1 95% 96% 96%

Switch:3 CPU:1

TID Name 5Sec 1Min 5Min
----------------------------------------------------------
3eb5430 tNet0 0.20% 0.17% 0.13%
3f53ea0 tXbdService 0.00% 0.08% 0.02%
4713b20 osapiTimer 2.20% 2.16% 2.13%
4a79ff0 bcmL2X.0 0.60% 0.53% 0.57%
4b26eb0 bcmCNTR.0 1.00% 0.94% 0.96%
4b9f490 bcmTX 1.00% 1.01% 1.19%
53b9f40 bcmRX 16.00% 15.57% 16.38%
54042f0 bcmATP-TX 25.60% 22.90% 23.34%
54097f0 bcmATP-RX 0.00% 0.08% 0.14%
59fb7f0 MAC Send Task 0.20% 0.20% 0.20%
5a0ccf0 MAC Age Task 0.20% 0.06% 0.05%
6e02f30 bcmLINK.0 0.40% 0.40% 0.40%
90e38d0 osapiMemMon 2.20% 2.47% 2.63%
91177f0 SysIdleTask 2.40% 1.64% 1.74%
920dce0 C5IntProc 0.00% 0.11% 0.07%
9dfe8b0 hapiRxTask 2.00% 1.81% 1.86%
9e33d40 tEmWeb 0.40% 0.32% 0.18%
b61e280 EDB BXS Req 0.00% 4.58% 2.32%
b763a90 SNMPTask 0.00% 1.30% 0.68%
b7ab5d0 RMONTask 0.00% 0.31% 1.24%
e2f2e30 dot1s_timer_task 1.00% 1.00% 1.00%
106fa4a0 fftpTask 0.00% 0.04% 0.01%
10793cc0 ipMapForwardingTask 42.60% 39.87% 40.37%
10c3a880 ARP Timer 0.20% 0.03% 0.00%

And this is what we saw in the logs. There was a topo change, but it had happened almost 2 hours before.

<166>Mar 1 07:21:45 10.10.1.1-3 DOT1S[238044000]: dot1s_ih.c(1485) 2257 %% Setting Port(130) instance(4095) State: DISCARDING<166>Mar 1 07:21:45 10.10.1.1-3 DOT1S[238044000]: dot1s_txrx.c(485) 2258 %% dot1sMstpTx(): CIST Role Disabled
<166>Mar 1 07:21:45 10.10.1.1-3 DOT1S[238044000]: dot1s_ih.c(1485) 2259 %% Setting Port(130) instance(0) State: DISCARDING
<166>Mar 1 07:21:45 10.10.1.1-3 DOT1S[238044000]: dot1s_sm.c(4253) 2260 %% Setting Port(130) Role: ROLE_DESIGNATED | STP Port(130) | Int Cost(2000) | Ext Cost(2000)
<166>Mar 1 07:21:47 10.10.1.1-3 DOT1S[238044000]: dot1s_ih.c(1360) 2261 %% Setting Port(130) instance(0) State: LEARNING
<166>Mar 1 07:21:47 10.10.1.1-3 DOT1S[238044000]: dot1s_ih.c(1424) 2262 %% Setting Port(130) instance(0) State: FORWARDING
<166>Mar 1 09:00:27 10.10.1.1-3 DOT1S[238044000]: dot1s_ih.c(1485) 2274 %% Setting Port(130) instance(0) State: DISCARDING
<166>Mar 1 09:03:31 10.10.1.1-3 DOT1S[238044000]: dot1s_txrx.c(485) 2277 %% dot1sMstpTx(): CIST Role Disabled
<166>Mar 1 09:03:31 10.10.1.1-3 DOT1S[238044000]: dot1s_ih.c(1485) 2278 %% Setting Port(123) instance(0) State: DISCARDING
<166>Mar 1 09:03:31 10.10.1.1-3 DOT1S[238044000]: dot1s_txrx.c(485) 2279 %% dot1sMstpTx(): CIST Role Disabled
<166>Mar 1 09:03:31 10.10.1.1-3 DOT1S[238044000]: dot1s_ih.c(1485) 2280 %% Setting Port(124) instance(0) State: DISCARDING
<166>Mar 1 09:03:31 10.10.1.1-3 DOT1S[238044000]: dot1s_ih.c(1346) 2281 %% Setting Port(445) instance(4095) State: DISABLED
<166>Mar 1 09:03:31 10.10.1.1-3 DOT1S[238044000]: dot1s_ih.c(1346) 2282 %% Setting Port(446) instance(4095) State: DISABLED
<166>Mar 1 09:03:40 10.10.1.1-3 DOT1S[238044000]: dot1s_ih.c(1485) 2283 %% Setting Port(123) instance(4095) State: DISCARDING
<166>Mar 1 09:03:40 10.10.1.1-3 DOT1S[238044000]: dot1s_txrx.c(485) 2284 %% dot1sMstpTx(): CIST Role Disabled
<166>Mar 1 09:03:40 10.10.1.1-3 DOT1S[238044000]: dot1s_ih.c(1485) 2285 %% Setting Port(123) instance(0) State: DISCARDING
<166>Mar 1 09:03:40 10.10.1.1-3 DOT1S[238044000]: dot1s_sm.c(4253) 2286 %% Setting Port(123) Role: ROLE_DESIGNATED | STP Port(123) | Int Cost(20000) | Ext Cost(20000)
<166>Mar 1 09:03:40 10.10.1.1-3 DOT1S[238044000]: dot1s_ih.c(1360) 2287 %% Setting Port(123) instance(0) State: LEARNING
<166>Mar 1 09:03:40 10.10.1.1-3 DOT1S[238044000]: dot1s_ih.c(1424) 2288 %% Setting Port(123) instance(0) State: FORWARDING
<166>Mar 1 09:03:40 10.10.1.1-3 DOT1S[238044000]: dot1s_ih.c(1503) 2289 %% Setting Port(445) instance(4095) State: MANUAL_FORWARDING
<166>Mar 1 09:03:40 10.10.1.1-3 DOT1S[238044000]: dot1s_ih.c(1503) 2290 %% Setting Port(446) instance(4095) State: MANUAL_FORWARDING
<166>Mar 1 09:03:40 10.10.1.1-3 DOT1S[238044000]: dot1s_ih.c(1485) 2291 %% Setting Port(124) instance(4095) State: DISCARDING
<166>Mar 1 09:03:40 10.10.1.1-3 DOT1S[238044000]: dot1s_txrx.c(485) 2292 %% dot1sMstpTx(): CIST Role Disabled
<166>Mar 1 09:03:40 10.10.1.1-3 DOT1S[238044000]: dot1s_ih.c(1485) 2293 %% Setting Port(124) instance(0) State: DISCARDING
<166>Mar 1 09:03:40 10.10.1.1-3 DOT1S[238044000]: dot1s_sm.c(4253) 2294 %% Setting Port(124) Role: ROLE_DESIGNATED | STP Port(124) | Int Cost(20000) | Ext Cost(20000)
<166>Mar 1 09:03:40 10.10.1.1-3 DOT1S[238044000]: dot1s_ih.c(1360) 2295 %% Setting Port(124) instance(0) State: LEARNING
<166>Mar 1 09:03:40 10.10.1.1-3 DOT1S[238044000]: dot1s_ih.c(1424) 2296 %% Setting Port(124) instance(0) State: FORWARDING
<166>Mar 1 09:04:52 10.10.1.1-3 DOT1S[238044000]: dot1s_ih.c(1485) 2297 %% Setting Port(130) instance(4095) State: DISCARDING
<166>Mar 1 09:04:52 10.10.1.1-3 DOT1S[238044000]: dot1s_txrx.c(485) 2298 %% dot1sMstpTx(): CIST Role Disabled
<166>Mar 1 09:04:52 10.10.1.1-3 DOT1S[238044000]: dot1s_ih.c(1485) 2299 %% Setting Port(130) instance(0) State: DISCARDING
<166>Mar 1 09:04:52 10.10.1.1-3 DOT1S[238044000]: dot1s_sm.c(4253) 2300 %% Setting Port(130) Role: ROLE_DESIGNATED | STP Port(130) | Int Cost(2000) | Ext Cost(2000)
<166>Mar 1 09:04:54 10.10.1.1-3 DOT1S[238044000]: dot1s_ih.c(1360) 2301 %% Setting Port(130) instance(0) State: LEARNING
<166>Mar 1 09:04:54 10.10.1.1-3 DOT1S[238044000]: dot1s_ih.c(1424) 2302 %% Setting Port(130) instance(0) State: FORWARDING

We had this happen in the past with a single Netgear junk switch that someone had plugged in at their desk. It turned out that it would cause the same symptoms every day when the person would boot it up. There was no loop anywhere on the switch at that time.

Any ideas on where to begin?

[Jason_Wisniewsk]

I have the L3 configured as a central hub with spokes going out to each of my IDFs plus a few VLANs for physical vs virtual, etc, so a packet sniffer on one of my VLANs will only capture those packets, unless we are seeing a spillover into multiple VLANs. My gut feeling is that it isn't, though.

'set vlan port' isn't a command I recognize on the B/C, but I am working from memory currently. I did mean to set a port with every VLAN egress'd through that would be sniffed via Wireshark.

[Mike_D]

Jason

the set vlan port command will allow you to add egress for each vlan to a particular port - tagged or untagged.

(vs set port vlan command which sets pvid and egress)

I wouldn't bother with tagging - traffic source tends to be easy to identify and tags can confuse some laptops. But I guess that's a chocolate or vanilla call.

That's how I'd do it to start with. traffic doing this sort of damage in many cases floods a vlan and this approach throws a wide net. you should see little traffic - mostly arp - in a healthy environment.

Regards

Mike

[Jason_Wisniewsk]

What are your thoughts on how to prepare for a packet sniff? Build a port that has every VLAN tagged to it and throw the sniffer on that one? Building it one VLAN at a time will take a long time, as I have approximately 30 in this location

[Mike_D]

The addition of an ARP entry will allow routing of the NLB traffic but to protect the L2 switch and maximize throughput there's a setting called unicast as multicast in which you name the mac address and the egress vlan and ports. This statically builds a hardware path where normally the mcast mac hits the flood path as the address cant be learned in the FDB.

set mac unicast-as-multicast enable

set mac multicast 03-bf-xx-xx-xx-xx ge.1.1-10

Hang in there. Keep brainstorming.

I agree with all of Jeremy's input. Wireshark should be attached to the network and ready for action.

Easy to say from my position but troubleshoots always look boogery and bizarre while you're in the middle. But its always something. And you'll eventually find that something. And then it will make perfect sense. And generally you've learned something by then.

[Jeremy_Gibbs]

Sounds like you might want to break out wire shark and do some captures. Are you using any default routes? Also, what is upstream from the C?