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4506 and IPV6 Unicast

Good morning - Recently I've had the pleasure of dealing with my corporate network ( and all remote sites) coming to a screeching halt.  It turns out that new Lenovo and HP laptops have a "bug" where they flood out multicast traffic when IPV6 is enabled.  When all of my sites started dropping, I checked my processor stats by running the sh processor cpu sorted | exec 0.0 command, and sure enough it was pegged at 99%. The top process was Cat4k Mgmt LoPri, and we later traced down the culprit.

At any rate, as we do not use IPv6, I would really like to disable any and all ipv6 traffic on my core switch.  I've found a couple ways to go about doing this, but I thought I'd check here to see what the best approach is. As I stated earlier, we do not use IPv6 in any fashion, and I need a fail-safe in place in the event that ipv6 is not turned off when network devices are deployed...


Thanks for any input!

Cisco Employee

Hello,We are seeing a lot of


We are seeing a lot of customers experiencing this concern. The problem is not HP or Lenovo - it is the type of NIC you are using. If you look at the NIC details, you will find out that these are all Intel i217 NICs. It appears that every time these machines sleep, the NIC floods out IPv6 multicast packets (as you have rightly stated).

Several workarounds at the source of the problem:

1. Using power management, disable the sleep feature of these machines.

2. Upgrade the driver for this NIC to the latest one (a new driver update was released a couple of weeks back I believe).

In regards to Cisco switches, different platforms will have different tools available to stop this. A common one should be a VACL which drops these packets (packets destined to 3333.XXXX.XXXX). Of course, this is not a very good workaround if you're using IPv6 in your environment. In that case, stopping this at the source is most critical.




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