What is VLAN 0, and how do I get a workaround for this problem?

Question

To make a long story short, we have a 6500 L3 switch as our core switch for our corporate LAN. There is a 3550 connected to it by fiber, and a 3750 is connected to the other side of it also by fiber. I can go to the 3550 in the middle and ping/telnet either way, but can't do a complete ping or telnet from either end to the other end.
This afternoon I tried a L2 traceroute back to the gateway of the vlan, and came up with this output --
switch#traceroute mac ip 10.121.1.77 10.121.1.1
Source and Destination arped on different vlans (source on vlan 0 and destination on vlan 1).
Layer2 trace aborted.
Nothing shows up regarding Vlan 0 on the 3550 when I execute 'show vlan'. VTP is set correctly, all vlans are populated, and L3 routing is turned off. Where does VLAN 0 come from, and how do I get the switch address on Vlan 1?
Thanks,
Jim

Answer 1

Where are you issuing the L2 traceroute.
Understanding Layer 2 Traceroute
The Layer 2 traceroute feature allows the switch to identify the physical path that a packet takes from a source device to a destination device. Layer 2 traceroute supports only unicast source and destination MAC addresses. It determines the path by using the MAC address tables of the switches in the path. When the switch detects a device in the path that does not support Layer 2 traceroute, the switch continues to send Layer 2 trace queries and lets them time out.
The switch can only identify the path from the source device to the destination device. It cannot identify the path that a packet takes from source host to the source device or from the destination device to the destination host.
Switches Supporting Layer 2 Traceroute
The Layer 2 traceroute feature is available on these switches:
* Catalyst 2950 switches running Release 12.1(12c)EA1 or later
* Catalyst 3550 switches running Release 12.1(12c)EA1 or later
* Catalyst 4000 switches running Catalyst software Release 6.2 or later for the supervisor engine
* Catalyst 5000 switches running Catalyst software Release 6.1 or later for the supervisor engine
* Catalyst 6000 switches running Catalyst software Release 6.1 or later for the supervisor engine
But the above might not be the issue as you said from 3550 you can ping either 3750 or the 6500, the traceroute looks like you did from 3550. What you need to do is make sure that the 3750 and the the vlan for 10.121.1.1 are in the same vlan.