[c-nsp] unicast IPv4 packets punted on Cisco 4500

[Martin T]

Thanks!


Martin

On 10/23/14, Andras Toth <diosbejgli at gmail.com> wrote:
> Hi Martin,
>
> On Catalyst 4500 the MAC learning is done by CPU.
>
> Catalyst 6500 (at least with Sup32 & Sup720), and Nexus switches perform
> MAC learning in hardware.
>
> Best regards,
> Andras
>
>
> On Wed, Oct 22, 2014 at 1:58 PM, Martin T <m4rtntns at gmail.com> wrote:
>
>> Hi,
>>
>> thanks for all the replies! I overlooked the "SA Miss" field. I guess
>> the reason why source MAC address needs to be re-learned is that it's
>> flapping between the ports Gi6/45 and Gi6/48. As I explained,
>> "Ethernet tester" sends out frames with source MAC address
>> 00:00:00:00:00:11 and destination MAC address 00:18:63:00:32:76 to
>> Gi6/45 port and those frames are hardware-looped to port Gi6/48 with
>> the same source MAC address.
>> So in order to avoid the high CPU utilization because of source MAC
>> address re-learning, I can:
>>
>> 1) create a static MAC address-table entry("mac address-table static
>> 0000.0000.0011 vlan 900 interface GigabitEthernet6/48" or "mac
>> address-table static 0000.0000.0011 vlan 900 interface
>> GigabitEthernet6/45")
>> 2) disable MAC address learning for VLAN 900("no mac address-table
>> learning vlan 900")
>>
>> First command normalizes the CPU usage, but switch seems to drop the
>> traffic if MAC address table entry points to a different port where
>> the frame came in from. With disabling the MAC address learning I'm
>> able to achieve what I needed.
>>
>>
>> Is this Cisco Catalyst 4500 series platform-specific behavior that MAC
>> address table entries are done by switch CPU? Or is this so for all
>> the Catalyst and Nexus switches?
>>
>>
>> thanks,
>> Martin
>>
>> On 10/21/14, Lukas Tribus <luky-37 at hotmail.com> wrote:
>> >> "Event: SA Miss" means that the MAC Source Address needs to be learnt
>> (or
>> >> re-learnt) so the switch send a copy of the packet to CPU for learning
>> the
>> >> MAC address. Perhaps the MAC is not learn yet, or the aging timer is
>> >> too
>> >> low, or the MAC is learnt on another port already and it's flapping.
>> >
>> > Or the traffic generator uses random source mac addresses.
>> >
>> >
>> > Lukas
>> >
>> >
>>
>