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I am experiencing high CPU utilization on a Cisco 3750. After consulting with Cisco TAC, it seemed we get a lot of icmp request that the switch redirects so asked what if I disabled the "ip redirect" but Cisco TAC said that platform does not support it but I did "no ip redirect" on all hsrp interfaces anyways and after reviewing "debug platform cpu-queues icmp-q" output I see huge number of messages like this:

Jun 28 2016 16:06:04: ICMP-Q:Dropped redirect disabled on L3 IF: Local Port Fwding L3If:Vlan52 L2If:TenGigabitEthernet1/1/2 DI:0xB4, LT:7, Vlan:52   SrcGPN:54, SrcGID:54, ACLLogIdx:0x0, MacDA:0000.0c9f.f002, MacSA: 0015.5d3e.1414   IP_SA:37.254.53.28 IP_DA:172.17.100.65 IP_Proto:17

Is there such a thing that this platform doesn't support "no ip redirect"? Cisco hasn't been able to give me any useful information.

"no ip redirect" is being applied to SVIs on the switch and act as a default gateway for the hosts and do static routing for them.

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  • It would help a lot if you edit your question to include the switch configuration. The no ip redirects command can be used on layer-3 interfaces if you have routing enabled.
    – Ron Maupin
    Jul 4 '16 at 17:26
  • Thank you @RonMaupin. You are correct. This is being used on SVIs. I finally got an answer from Cisco: "Because of hardware limitation, "no ip redirect" does not work in Catalyst 3560 and 3750. If routing is performed on access switch and the next hop of the packet is a host on the same subnet of the ingress layer 3 interface, the frame is still punted to the CPU.". Also there is this supportforums.cisco.com/discussion/11410821/…
    – Fanttazio
    Jul 7 '16 at 8:56
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I got a response from Cisco:

“Because of hardware limitation, "no ip redirect" does not work in Catalyst 3560 and 3750. If routing is performed on access switch and the next hop of the packet is a host on the same subnet of the ingress layer 3 interface, the frame is still punted to the CPU.”

And there is also this thread https://supportforums.cisco.com/discussion/11410821/flooding-icmp-q-3750-switch

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