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Warhawk72Flag for United States of America

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Router interface response time isssue

I  have been moving from an older Cisco 4500 series switched/routed  network to Core Brocade MLX16 switched/routed network. The project is ¾ complete. I am seeing some weird ICMP responses coming from any of the Cisco VLAN interfaces (not yet migrated) or the Brocade VE’s. As we are have phased the rollover by VLAN’s and their contents. I have set the RSTP priorities to be balanced on the two new Brocade cores. Whichever switch owns the root, also owns the VRRP-E master role. The Cisco switches are setup similar, using HSRP.
If I ping any (brocade) VE or (Cisco) VLAN interfaces, or their VRRP-E/HSRP interface, I am seeing response like the ones below. If I ping any other devices, on the same VLAN or across the routers on other VLAN’s, be it,  Servers, workstations etc, we are seeing no variations. All within 1 MS.

Not sure why the Router interfaces are responding like that. We are seeing no high utilization via Orion, or SFLOW.

It concerns me. Does anyone have an idea where to start?

Reply from ??.??.60.1: bytes=32 time<1ms TTL=64
Reply from ??.??.60.1: bytes=32 time=1ms TTL=64
Reply from ??.??.60.1: bytes=32 time=14ms TTL=64
Reply from ??.??.60.1: bytes=32 time=6ms TTL=64
Reply from ??.??.60.1: bytes=32 time<1ms TTL=64
Reply from ??.??.60.1: bytes=32 time<1ms TTL=64
Reply from ??.??.60.1: bytes=32 time<1ms TTL=64
Reply from ??.??.60.1: bytes=32 time<1ms TTL=64
Reply from ??.??.60.1: bytes=32 time<1ms TTL=64
Reply from ??.??.60.1: bytes=32 time<1ms TTL=64
Reply from ??.??.60.1: bytes=32 time<1ms TTL=64
Reply from ??.??.60.1: bytes=32 time<1ms TTL=64
Reply from ??.??.60.1: bytes=32 time<1ms TTL=64
Reply from ??.??.60.1: bytes=32 time<1ms TTL=64
Reply from ??.??.60.1: bytes=32 time<1ms TTL=64
Reply from ??.??.60.1: bytes=32 time<1ms TTL=64
Reply from ??.??.60.1: bytes=32 time<1ms TTL=64
Reply from ??.??.60.1: bytes=32 time<1ms TTL=64
Reply from ??.??.60.1: bytes=32 time<1ms TTL=64
Reply from ??.??.60.1: bytes=32 time<1ms TTL=64
Reply from ??.??.60.1: bytes=32 time<1ms TTL=64
Reply from ??.??.60.1: bytes=32 time=19ms TTL=64
Reply from ??.??.60.1: bytes=32 time=19ms TTL=64
Reply from ??.??.60.1: bytes=32 time=19ms TTL=64
Reply from ??.??.60.1: bytes=32 time=19ms TTL=64
Reply from ??.??.60.1: bytes=32 time=19ms TTL=64
Reply from ??.??.60.1: bytes=32 time=19ms TTL=64
Reply from ??.??.60.1: bytes=32 time=6ms TTL=64
Reply from ??.??.60.1: bytes=32 time=18ms TTL=64
Reply from ??.??.60.1: bytes=32 time=4ms TTL=64
Reply from ??.??.60.1: bytes=32 time=16ms TTL=64
Reply from ??.??.60.1: bytes=32 time<1ms TTL=64
Reply from ??.??.60.1: bytes=32 time<1ms TTL=64
Reply from ??.??.60.1: bytes=32 time<1ms TTL=64


Avatar of cdowdy
cdowdy

Are your switches utilizing any control plane policing? CoPP can and does cause exactly this behavior on my Nexus core when pinging directly to a destination IP on the core switch itself, but not through it as the pings destined to the switch could be DoS attack and as such, the CoPP configuration rate limits the replies.
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cdowdy

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ASKER

thank you for your recommendations.
It turns out that the Processor answers ICMP requests for all VE's and VRRP-E interfaces. Where as icmp traversing to another VLAN is switched/routed via the hardware. So depending on what the processor is doing at any one moment you can see random spikes in ICMP response time.

This is the response I received from Brocade:

1.      Weird ICMP ping time to VE and VRRP interfaces. Intermittently, we see the ping response to the VE and VRRP interfaces on the MLX devices go from <1ms to about 9-10ms. But we do not see any latency while pinging actual devices connected on the same VLAN.

"This is not weird but is normal. While pinging the VE and VRRP interface, we are going through the CPU. Anytime there is higher traffic or any other process that is using CPU resources, we will see some latency in the pings. Whereas, the same issue is not seen on other devices connected as we are going through hardware and are not using CPU resources."[