Please explain output from "show mac address-table int g2/0/14"

Unanswered Question
Jun 15th, 2010


On a blade center switch WS-CBS3110G-S-I  i entered the following command:

show mac address-table int g2/0/14.

I received the following output:

BladeSw#sho mac address-table int g2/0/14

          Mac Address Table


Vlan    Mac Address       Type        Ports

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

2000    0021.5e99.b690    BLOCKED     Gi2/0/14

4095    0021.5e9d.b670    DYNAMIC     Gi2/0/14

  10    0021.5e99.b690    DYNAMIC pv  Gi2/0/14

Total Mac Addresses for this criterion: 3

1. What does the type BLOCKED mean?  The port is not blocked neither from a security point of view ( no port security defined) and not

     from a spanning tree point of view. It is an edge port and in a forwarding state.  So what and why is is it blocked?

2. What is Vlan 4095 ?  I have no definitions for this Vlan - none not primary not private nothing. So where does this number come from ?

The answers may be relevant to why the server on this port is unreachable ( no ping ).

The  interface state is up up. It is defined to be in private vlan 2000 which is in primery vlan 10 and is of type isolated.

Thanks for any help


I have this problem too.
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jayaprakashece Tue, 06/15/2010 - 05:35

Hi Mickey,

          VLAN 0 & 4095 are reserved VLANs for system internal use. Vlan 4095 is also called discard VLAN. and it is usually exists in VMware environment. It is also used for blade switch management some times.

And as the port is configured for a private VLAN, the MAC address of the end host is being learned in both isolated and promiscious VLANs.

It is BLOCKED in vlan 2000 because this VLAN is an isolated VLAN.So, to prevent any communication with other hosts in this VLAN , the MAC address will be in blocked state.

This port is allowed to communicate with promiscious vlan ports and hence the same MAC address is being learned in VLAN 10 as well.



mikik Tue, 06/15/2010 - 05:54

Hi Jaya;

thanks for the explanation. As such it seems that my config is OK and have

to look further for the problem.

Again thanks.


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