trunking disruption

[hill17]

I'm primarily a routing guy but I need to create some vlans and start trunking a fiber link connecting some 3750 switches and away we go.
My big problem is that this is a production network between 8am and 7pm and because of personal committments I cannot stay late anytime to do this but I still need to do this in the next few days. So I'm wondering if I implement trunking on these ports what type of disruption are we looking at? I assume there's some form of re-negotiation, would the links be down for long? or would they be down at all?

 

[pmesjar]

It can take about a minute till switches put their trunked ports up and running, which is not because of trunk config but because of STP. However since you want trunking, you are going to separate users to VLANs, aren't you? So there will also be end host disruption as you will be assigning ports to right VLAN. If everything is well prepared I don't think the disruption should last more than 20 minutes (depends also on how many devices are you going to configure and how fast typer you are

However the only disruption you need to be affraid is Spanning Tree recalculation. You can speed up ports to where your end users are connected (not switches!!!) using:

Switch(config-if)# spanning-tree portfast

Let me know if you need futher assistance

Peter Mesjar
CCNP, A+ certified
pmesjar@centrum.sk

"The only true wisdom is in knowing you know nothing.

 

[hill17]

Great that worked like a charm, that's the problem with having ip phones aswell if you take down the network you take down everything.
Incidentally in order for this to work it has to pass through 4 switches and if I deleted the vlan I created off any of the switches in the middle if failed to work.
Thanks again

 

[pmesjar]

If you need better and centralized control of creating and deleting VLANs, configure VTP (Virtual Trunking Protocol). This way one switch will act as VTP Server, sending VLAN config info to VTP clients and only VTP Server can delete VLANs. However be aware of that even VTP client can erase VLAN configuration on VTP server. Do a search through:

http://www.cisco.com/univercd

I'm sure you will get tons of info on VTP.

Peter Mesjar
CCNP, A+ certified
pmesjar@centrum.sk

"The only true wisdom is in knowing you know nothing.