access ports

[DRUK]

Hi,

I know this sounds crazy but I am finding problems linking up a Management switch to all Cisco switches on the LAN. I am linking them up using the usual crossover cable; the ports are set up for vlan 915 (inter switch/VLAN connectivity works too) which is the management VLAN being used. Port security is disabled and so is portfast.

When the switches are linked up, the port on the management switch comes and goes down continuously. I tried forcing the seep and duplex to 100/full but it still happens.

Has anyone ever seen this before or know what it could be?

Cheers.

[paddyxdoyle]

Hi,

When you say continuously going down is this each time you connect a port on your management switch to another switch (so the port transitions to up and then down once) and when you unpatch and then repatch the connection it does it again, or is each port flapping up and down continuously?

If have seen similar to the first situation when putting interfaces on a 3550 switch into a specific VLAN, without creating the VLAN in the VLAN database first.

Could this apply here?

Thanks

PD

[DRUK]

Hi,

When I patch the cable in and leave it in, the port is 'flapping' continuously. This only seems to happen on the Management switch though. The conection at the other end shows no connection at all.

The VLAN has been created on both of the VTP servers and inter VLAN connectivity seems to be fine.

I've gone over the configs here to check if there's anything obviouse like port security but it's disabled throughout the LAN.

It can't be SPT can it? Would a loop cause this error?

[paddyxdoyle]

As long as spanning tree is running and portfast isn't enabled on your ports then STP shouldn't cause an issue. Plus it sounds like you don't have your management VLAN trunked between all your switches thus creating a potential loop.

Have you used this switch before, what happens if you patch a PC into this switch?

Rgds

PD

[sstudsdahl]

The other thing to make sure of is that you don't have bpduguard enabled on the ports between the two switches. If this feature is enabled, either on the individual port or globally, the port will shut itself down upon receipt of a BPDU frame. If you also have errdisable recovery setup, the port will re-enable itself after the configured time period.

[DRUK]

Its not BPDU Guard either, that's disabled too.

Thanks.

[DRUK]

It doesn't seem to be that either.. I did initially find that the management switch was set as a vtp server instead of client. Just to be sure I set it back to client, erased the vlan.dat file and reloaded the switch.

Trunking is fine between the management switch and the core switches too. Spanning-Tree is running and portfast is disabled as well.

When I patch the management switch across to one of the core switches, the port on the management switch comes up and stays up and yet on the core switch the port is physically down! I feel like Im chasing my tail!