02-11-2009 01:12 AM - edited 03-06-2019 03:58 AM
I'm about to place our new 3560 switch onto the network. There are 9 other cisco switches on this network. Is there anything I should check before placing the new switch on the network? Is it safe to just place it on the network? I don't wanna take the whole network down!
02-11-2009 02:05 AM
Hi Kaamil
If you are using VTP ( ie non transparent mode everywhere ), I would be checking all the relevent details about that ie domain / mode / version , if unsure, set it to vtp transparent mode.
Also check what spanning tree version you are running and if you have changed any of the priority's, check that this new switch wont take over as the root ( unless that's what you want).
02-11-2009 05:20 AM
What should I check for so that the new switch wont take over as the root? Where can I find out more about VTP? & Is there somewhere that I can check for all these commands?
02-11-2009 07:02 AM
Hi
To check the status of VTP type the following:-
show vtp status
VTP Version : 2
Configuration Revision : 0
Maximum VLANs supported locally : 1005
Number of existing VLANs : 23
VTP Operating Mode : Transparent
VTP Domain Name :
VTP Pruning Mode : Disabled
VTP V2 Mode : Disabled
VTP Traps Generation : Disabled
MD5 digest : 0x90 0x18 0xBD 0x95 0xB5 0xE9 0x3A 0x17
Configuration last modified by 0.0.0.0 at 0-0-00 00:00:00
More VTP info here
http://www.cisco.com/en/US/tech/tk389/tk689/tk706/tsd_technology_support_sub-protocol_home.html
As for preventing the switch becoming the root, set the spanning tree priority to the highest as the lowest wins the election.
Set the priority to the highest 61440 for all vlans using :-
spanning-tree vlan 1-4094 priority 61440
02-11-2009 07:10 AM
Kaamil
In addition to Adam's posts
1) If you add a new switch and this switch is connected via a trunk link to your existing switches and all vlans are allowed on the trunk then there will be an STP reconvergence. You should add the switch out of hours or schedule downtime for it.
2) It's not clear whether you are running VTP Server/Client or not on your existing switches. To ensure that this new switch has a revision number of 0, on the switch
3560(config)# vtp mode transparent
then if you want it to be a vtp client just change it back to client mode ie.
3560(config)# vtp mode client
The above should be done before connecting the switch to the rest of your network.
As for becoming root, you can do as Adam suggested. A more long term approach is to pick 2 switches in your existing setup and make them root and secondary. That way you won't then have this issue again if you need to add a further switch.
Adding a switch to an existing network should always be done out of core production hours.
Jon
02-11-2009 03:55 PM
Make sure the uplink port(s) is either trunk, routed or disable portfast (no spanningtree portfast).
Another thing, if you are unsure about what you're doing, implement this after hours.
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