uplinks and trunks

If there was something you did not understand in my previous answer (the third time you'd asked the same question) then indicate the specific portion you had questions about and we will provide clarification.

While not attempting to be complete, here's a few things to do:

1) use 'switchport nonegotiate' 2) assign 'switchport trunk native vlan to be a separate vlan dedicated for this across all trunks that doesn't contain any hosts 3) use "udld port aggressive" 4) don't use vtp. configure all switches as transparent but configure a common vtp domain. This gets debated but generally agreed if your environment is fairly static. 5) only trunk vlans that are needed and only have vlans that are needed on the switches. 6) define a template for common config components and make it policy it gets used on all trunk ports

BernieM

I remember setting this command on one of my cisco 3750 switches.

switchport trunk native vlan2 on the uplink port and I ended up losing all connectivity to the hosts connected to this 3750. By default All ports are on vlan1. So If i suddenly set uplink port to vlan2, I will have problems right?

Changing uplinks from access to trunking is going to cause spanning-tree reconvergence so there is going to be a period of connectivity loss but if you have all the correct settings at both ends things should come back. You can't expect to do this during production time.

BernieM

You apply the configuration settings as mentioned previously. Apply "switchport mode trunk" last as that actually changes the mode from access to trunk and is when other 'switchport trunk' entries get applied.

Links between switches are fairly independent of each other so, yes, you can do one first and others when ever.

BernieM

I dont quite understand this one

2) assign 'switchport trunk native vlan to be a separate vlan dedicated for this across all trunks that doesn't contain any hosts

So far no hosts on this switch yet but I want to start plugging in the hosts. All ports on vlan1

so far I have on uplink gigabit 1/1

switchport trunk encapsulation dot1q switchport mode trunk udld port aggressive

What about the other end of the the link. The other end of this switch is a non cisco switch.

So if I am only running one Vlan in the entire network and I configure all my switches uplinks to the core switch as trunks. Are there any issues with this?

BernieM

can you elaborate on this

6) define a template for common config components and make it policy it gets used on all trunk ports

There could be depending on the number of hosts ... remember it's one big broadcast domain. I don't know off hand what the rule of thumb is but it would pay you to research it. If you have layer-3 capability in the core why not use it.

Configuring the uplinks as trunks is the best way to go even if you're only trunking a single vlan as it provides scalability ... you can add / remove vlans dynamically.

BernieM

This is documenting how trunks are configured and maintaining a common configuration across all trunks. I'm in the process of stabilising a somewhat troublesome network that has had sloppy adhoc changes made. An example of a common template for a trunk link is:

description switchport switchport trunk encapsulation dot1q\\ switchport trunk allowed , switchport mode trunk switchport trunk native vlan load-interval 30 udld port agressive spanning-tree bpduguard disable

BernieM