6500 series ... not populating mac-address table

Our core switch (6513, SUP720, MSFC3) is not creating all the mac-address
table entries it should be. This is causing traffic to be forwarded out
other interfaces unnecessarilly.

The 6513 has a vlan interface for that vlan configured with no ip-address
but is 'up'. It does create mac-table entries for 'some' hosts in that vlan
but not all.

Any ideas where to start looking .. without causing too much 'debug' output.

BernieM

 

What IOS version ?

 

Version 12.2(18)SXF3

 

Do not see any relelvant bugs on CCO.

Can you describe the situation a little further.

Is there any pattern to the ports for which the MAC addresses are
missing ?
type of module, port position on card, etc, log messages

Post the output of show vlan x, show bridge x

 

Our core switch (6513, SUP720, MSFC3) is not creating all the mac-> > > > address

Could this be 'by design'?

The MAC table age time for a VLAN gets set to
15 seconds for some period if a STP enabled port
goes up or down unless portfast is configured
on that port.

When a VLAN is present on two switches and
HSRP is in use it is possible that unicast flooding can
occur. This is now well documented on CCO.

The fix is basically to set the ARP timeout to
the mac-address table timeout and to eliminate
STP TC events by configuring portfast.

Search CCO for [hsrp unicast flooding]
You will get many hits.

 

Thanks for the reply ... but:

1) HSRP isn't configured on the switch not populating the mac-table.
2) It's not a 'timeout', unless it's aging out within 1 sec., as I've
pinged from one host to another while on the core switch. No mac-table
entry gets added. No mac-timeouts are set anywhere so they're all 5
minutes by default.
3) The ports in question are not bouncing.

Host access port is standard:

switchport
switcport access vlan x
switchport mode access
spanning-tree portfast

I'll add mode detail ... later. I'm sick now and have just spent the last
two days in and out of bed.

BernieM

 

Are the devices for which the mac-address-table entries are missing
directly connected to the 6513 in question ?

 

Traffic to the MAC addresses that are not in the mac-address-table
should be unicast flodded to all ports in the vlan.

To determine the MAC addresses that are being flooded, you can
configure


mac-address-table unicast-flood limit <limit in Kpps> vlan <vlan> alert

 

Please post output of

show vlan <x> ! for the affected vlan

show spanning-tree <x>

show bridge <x>

show mac-address-table vlan <x>

show module detail

 

Do you have server connected to that vlan using NIC teaming ?

 

fixed

I also have had this problem. The above command (well, a variation) has worked great.

On my 6509: mac-address-table limit vlan [123] action limit flood

Thanks Merv!