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
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 vlan alert
Please post output of
show vlan ! for the affected vlan
show spanning-tree
show bridge
show mac-address-table vlan
show module detail
Do you have server connected to that vlan using NIC teaming ?
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