Inquiry on trunking

[Aji B. Brillantes]

Hi I am planning to implement trunking on some of our procurve switches. I just want to ask if it will work on different cables like trunking a 1GB fiber and 100mbs CAT5 connection?

[Matt Hobbs]

Yes, that's fine. Just don't mix and match. In a trunk group, make sure both ends support the same speed and media type.

[Aji B. Brillantes]

Thanks Matt for your reply. Can you explain further on what you mean by don't mix and much? I will be creating a trunk group for example trk1 using interface 1 and 2. Interface 1 has a fiber connection or cable while interface 2 uses cat5 cable. Both ends are procurve switches.

[Matt Hobbs · Accepted solution]

No, you shouldn't do that (I hope the switch would give you an error if you tried to do that).

From the manual:

Port Connections and Configuration: All port trunk links must be point-to-point connections between a switch and another switch, router, server, or workstation configured for port trunking. No intervening, non-trunking devices are allowed. It is important to note that ports on both ends of a port trunk group must have the same mode (speed and duplex) and flow control settings.

In this instance, you should probably use spanning-tree instead to block the slower link but also give you failover redundancy.

[Aji B. Brillantes]

So I just have to make both interface 1 and 2 use 1 GB fiber connection. Thanks MATT!

[Colin Butcher]

The key thing is speed & duplex. Imagine two switches connected by a single trunk with two ports in the trunk group.

Each port to port link between the switches must be the same speed & duplex as all other members of that trunk group.

So, 1x copper 1Gbps FDX and 1x fibre 1Gbps FDX would be OK in a trunk, as would 2x fibre 1Gbps FDX or 2x copper 1Gbps FDX.

However, 1x fibre 1Gbps FDX (or 1x copper 1Gbps FX) will not mix with a different speed link (eg: 100Mbps FDX) in the same trunk group.

I generally set up all inter-switch links as trunk groups containing 2 adjacent ports, even if they only contain a single active port. Makes it easier to see how the switch is configured and lets you add bandwidth on-the-fly by just inserting the necessary cable or fibre. I also tend to use the dual media capable ports for inter-switch links, typically ports 21-24 (or 23-24) on a 24 port switch.

Cheers, Colin (http://www.xdelta.co.uk).

[OLARU Dan]

Hey, Brillantes: you still got the problem buggin'ya?

[Aji B. Brillantes]

Thanks Dan. My problem with trunking is already solved. Thanks once again.