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2950 empty mac address table

Hi all,

I've got a catalyst 2950 switch running IOS 12.1(9)EA1d and for some reason, show mac-address-table doesn't list any mac addresses. The switch is displaying default behaviour for a switch with no learned mac addresses, in that it's flooding all unicast requests.

Any help would be greatly appreciated!

Thanks in advance,

Ben.

Reply to
bhalicki
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Do you have VLANs configured? Did you have spanning tree turned off?

Reply to
Walter Roberson

Hi Walter,

Thanks for the reply.

One other VLAN was configured, but no interfaces were bound to it. I have removed the extra VLAN, but still no luck. STP has always been enabled.

Any other ideas?

Ben.

Reply to
bhalicki

Please quote context so that people don't have to fire up a browser and look in google to find your original post.

Missing context: the 2950 MAC table is staying empty and it is unicast broadcasting.

Turn off VTP?

Does the 2950 have directly attached hosts, or is it acting as an aggregator for other switches? Do the spanning tree computations for the attached switches all look correct?

The mentions of VLANs and VTP have to do with flooding that can happen if you have two devices both of which are routing into the same VLANs: devices in the middle might never hear the ARP broadcasts in such a case.

If you turn on RSPAN on the 2950 and look at the incoming packets with a sniffer, are you seeing reply packets to traffic going through and do the replies have the expected MAC?

It is odd for the MAC table to be completely empty: it should be learning the port for the incoming data.

Hmmm, you mention "another VLAN" -- are your ports set as "access" ports or are they bridging across into a VLAN?

Reply to
Walter Roberson

Walter Roberson wrote:

2950 has directly attached hosts. STP enabled on uplinks to other switches. All spanning tree config/computations look correct.

Thats what I thought. I've got other switches here, with a similar config and full mac tables.

Here's my config:

Current configuration : 1903 bytes ! version 12.1 no service pad service timestamps debug uptime service timestamps log datetime service password-encryption service sequence-numbers ! hostname alb-devel-2950 ! enable secret 5 ***** ! clock timezone UTC 10 ip subnet-zero no ip domain-lookup ip name-server 203.4.205.20 ip name-server 203.4.205.21 ! spanning-tree extend system-id ! ! interface FastEthernet0/1 no ip address ! interface FastEthernet0/2 no ip address ! interface FastEthernet0/3 no ip address ! interface FastEthernet0/4 no ip address ! interface FastEthernet0/5 no ip address ! interface FastEthernet0/6 no ip address ! interface FastEthernet0/7 no ip address ! interface FastEthernet0/8 no ip address ! interface FastEthernet0/9 no ip address ! interface FastEthernet0/10 no ip address ! interface FastEthernet0/11 no ip address ! interface FastEthernet0/12 no ip address ! interface FastEthernet0/13 no ip address ! interface FastEthernet0/14 no ip address ! interface FastEthernet0/15 no ip address ! interface FastEthernet0/16 no ip address ! interface FastEthernet0/17 no ip address ! interface FastEthernet0/18 no ip address ! interface FastEthernet0/19 no ip address ! interface FastEthernet0/20 no ip address ! interface FastEthernet0/21 no ip address ! interface FastEthernet0/22 no ip address ! interface FastEthernet0/23 no ip address ! interface FastEthernet0/24 no ip address ! interface Vlan1 ip address 203.4.205.19 255.255.255.0 no ip route-cache ! ip default-gateway 203.4.205.1 no ip http server ! ! ! line con 0 exec-timeout 0 0 password 7 ***** stopbits 1 line vty 0 4 password 7 ***** login line vty 5 15 password 7 ***** login ! end

"show mac-address-table" alb-devel-2950#show mac-address-table Mac Address Table

------------------------------------------

Vlan Mac Address Type Ports

---- ----------- ---- -----

IOS upgrade maybe??

Reply to
bhalicki

After upgrading the IOS, the mac address table now shows 4 entries, which is a start, but far from perfect. I've got 20 devices connected and communicating, so figure the table should contain a lot more than this.

Also, during POST, I now get:

00:00:18: %PLATFORM_CAT2950-3-SCHAN_OP_FAILURE: S-channel operation timeout for opcode ARL_INSERT_CMD cmic_schan_op ERROR: timeout (OP=0x11 polls=100000)

Ports fa0/17-fa0/24 remain administratively down. No shut on these interfaces results in:

alb-devel-2950(config-if)#no shut alb-devel-2950(config-if)#

000129: 00:51:44: Fa0/24 can't be brought up because it failed POST in loopback test

Am I looking at a hardware failure?

Thanks in advance,

Ben.

Reply to
bhalicki
  1. %PLATFORM_CAT2950-3-SCHAN_OP_FAILURE: S-channel operation timeout for opcode [chars]. This message means that there was a failure to read or write to an ASIC register or a memory location because of an ASIC internal bus failure. [chars] is the operation code.

Recommended Action: If the message recurs, copy the error message exactly as it appears on the console or in the system log, call your Cisco technical support representative, and provide the representative with the gathered information.

Related documents- No specific documents apply to this error message.

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Make

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