5412zl im Hub-Mode (All Pakets come in a port goes out off all ports)?

[Carsten M]

A 5412zl (SW: K12.05)
I see on a port ( this port is not mirrored ) Unicast IP pakets and not-multicast layer 2 frames from sessions that are not for this port. This was on a switch port not to be expected

Multicast, and broadcast traffic was filtered out by the sniffer tool.

Can it be that the 5412zl switch from switching to hub mode?

The network load of most ports is below 1%
In the Systemlog from the 5412zl are no entries about MAC address flapping.
What (other) reasons can still to this effect (Hub-mode) lead.

[Geir Olav Skei . · Accepted solution]

Hi Carsten,

The reason for unicast traffic being flooded could be due to MAC-address re-learning, but then you usually only see a few packets being flooded.

But I understand it so that you're experiencing this problem constantly?

A reason for Unicast flooding could be an application spoofing MAC-addresses and thus filling up the MAC-table, rendering the switch unable to learn new MAC-addresses.
- It switches to "hub mode".
- If you do a 'show mac', you'll quickly find out if the MAC table is clogged with spoofed macs.

I see you are running K.12.05 and you should therefor upgrade to K.12.57 as it contains a few mixes regarding ARP and MAC.
- http://www.hp.com/rnd/software/j86921257.htm

Hope this helps.

--Gos

[Carsten M]

Thanks Gos!
I will this examine sometimes.

[Matt Hobbs]

Also check your spanning-tree topology, if it is constantly changing it will be clearing the mac-address cache and flooding packets to unknown destinations. Check 'show span' and look for 'time since last change'. In fact, I'm willing to bet a few bucks on this being the problem as there was an issue with K.12.05 and spanning-tree causing excessive topology changes. This has been fixed in the latest code.

[Carsten M]

Hallo Matt!

Yes, we have also many topology-changes.
The switches works with mstp spanningtree and the Topology changes everything from 2 to 45 seconds.

As next we plan a upgrade to K.12.57


Thanks!

[Carsten M]

SW Upgrade helps foe solution