When Is A Trunk Not A Trunk?

Very good article here – http://networkingnerd.net/2011/02/02/when-is-a-trunk-not-a-trunk/

Particuly like setting of Native vLAN and tagged networks over an HP trunk;

So, if HP refers to an uplink carrying multiple VLANs are a tagged port, then does HP have a “trunk”? In fact they do. In HPvania, a trunk is a logical construct that aggregates multiple ports into one logical link. For those of you that might be out there scratching your heads about this one, this means that when you “trunk” a group of ports on an HP switch, you are creating one LACP link from up to four individual ports. This kind of configuration should look like this:

Switch(config)#trunk 19-24
Switch(config-trk)#vlan 1
Swtich(config-vlan)#untagged trk1
Swtich(config-vlan)#vlan 10
Swtich(config-vlan)#tagged trk1
Swtich(config-vlan)#vlan 99
Swtich(config-vlan)#tagged trk1

Those of you that are fans of irony will appreciate that the above config sets up this LACP port aggregation to pass multiple VLANs to another switch. In other words, we are configuring a Cisco “trunk” on top of an HP “trunk”.

HP ProCurve 5400zl Switch Series – How to Enable Jumbo Frames?

I couldn’t find how to do this via the web GUI (hate the new 5400 web console – what happened to the performance graphs??) — anyhow this is the commands to do it via commandline…

5406zl-A# show vlan 200
Status and Counters – VLAN Information – Ports – VLAN 200   VLAN ID : 200  Name : VLAN200   Status : Port-based   Voice : No   Jumbo : No

5406zl-A# configure
5406zl-A(config)# vlan 200 jumbo
5406zl-A(config)# end
5406zl-A# sho vlan 200

Status and Counters – VLAN Information – Ports – VLAN 200  VLAN ID : 200   Name : VLAN200   Status : Port-based   Voice : No  Jumbo : Yes

From a windows box…

ping -f -l 8972

Router on a stick – Adding VLANs to a cisco router

Telnet to your cisco router, enable then go into config t. Passwords may be required depending on how it has been configured…


config t

Ensure that ip routing has been enabled…

ip routing

To create the VLAN adapter you’ll need to run the following commands to create a “router on a stick”…   Note: the .2 after the interface name creates a virtual adapter on the interface.

interface FastEthernet1/1.2
description “VM Host Network”
encapsulation dot1Q 2
ip address

The following is another example of a VLAN (110) on a router. This one has the ip helper-address (DHCP server) specified for this range.

interface FastEthernet1/1.110
description “Ak IDN”
encapsulation dot1Q 110
ip address
ip helper-address

That is the router side of things setup. Remember to save your changes via…

copy run start

Now you’ll need to add the VLAN to your switches. If you have VTP in your environment its as simple as adding the extra vlan onto your “server” vtp switch. Telnet (or null cable) to your “server” switch and go into “enable” mode, then go into the vlan database and add the required vlans as per above…


vlan database

vlan 2 name “VM Host Network”

vlan 110 name “Ak IDN”

VTP will propagate the vlans out to your client switches. Done.