Trunking on Procurve 5412ZL

[4755898]

Being trying to setup the trunking on the 5412 switch. I enable the trunk group and is somewhat working. ( If I unplug one of the trunk, the other one will kick in and vice versa). However, I can't them to combine togeather as one big connection. Is there any special procedure to get this function to work?

 

[cajuntank]

Link aggregation or "Port Trunking" in HP world is the combination of up to 4 or 8 (depends on the switch) links into a logical link. HP offers two methods of doing this:
1. HP port trunking
2. LACP -Link Aggregation Control Protocol

Both require same speed links with LACP adding the additional requirement of operating in full-duplex mode.
Both methods distribute the load evenly across all links involved in the trunk.
Think of it like you have a 2 lane highway whose speed limit is 65mph. With "port trunking", you increase the highway to say a 4 lane highway, but the speed limit is still 65mph... Your just given the opportunity to have more cars on the highway than before, but there still bound to go the speed limit.

To configure "port trunking" from the config prompt:

switch(config)# trunk A1,A2 trk1 trunk

trunk -starts the command
A1,A2 -ports to add to the trunk
trk1 -trk1, trk2, etc... are fixed label names for trunks
trunk -do not use protocol to create or maintain trunk;
instead of using trunk at the end, you could have opted for LACP - which would use the 802.1ad link aggregation protocol to create and maintain the trunk.

Only after creating the trunk can you then add the trunk to a specific VLAN.
Note LACP does require additional configuration than stated above, but "port trunking" is the default.

Again, if you have 2 links in your trunk, you are not creating a 2Gb pipe between your switches, you are just adding a lane to your highway to allow more cars to travel the 1Gb road at the same time.

Hope that makes sense and helps out. Let me know.
Thanks.

 

[LawnBoy]

Excellent post, cajuntank. I prefer LACP, it's easy to configure.


"We must fall back upon the old axiom that when all other contingencies fail, whatever remains, however improbable, must be the truth." - Sherlock Holmes

 

[4755898]

Thanks for the clarification, cajuntank. Is there any advantage of going LACP instead of "trunk".

 

[cajuntank]

There are pro's and con's for each:

LACP -is a standards based that can be used across varied switch manufacturers and since it's a protocol, it handles some things automatically between itself and other LACP switches with same speed connections between each other. LACP also supports ports being in standby and will use those standby ports if it detects new members (additional switches) to the trunk group; however, LACP trunks, since they're dynamic, don't appear in the switches configuration; therefore, they always take default interface parameters. You also lose the feeling of control since the trunking happens automatically.


Static Port Trunking
The default static trunks appear in the switch's configuration and can therefore accept any parameters you would assign to a single port; however, no standby links are supported. Static links cannot detect new members of the trunk group, so no support for standby links like LACP; however, static trunking does give the administrator more control over the operation the the trunk ports.

Both methods share on important limitation in the area of load sharing; they are static methods. They do not adjust to reflect traffic volume on the links or make any evaluation to determine which link would be best at the given moment. They just distribute traffic evenly across all links which "generally" balances the load.

Hope I could help.