This article briefly explains how to integrate a HP Procurve and Cisco in one network, and make sure the VLANs are correctly routed across the two switches. I avoid using the term "trunk" as the definition of a "trunk" differs greatly between Cisco and HP: a trunk on a HP Procurve refers in fact to a feature like Cisco's EtherChannel, something entirely different.

Note that for VLAN trunking to work between the two, you need to use the 802.1q protocol. Other protocols, such as Cisco's VTP and ISL do not work on HP Procurve, as they are both Cisco-proprietary.

Multi-port trunking is also outside the scope of this article, but the basics remain the same.

Common configuration

For both switches, you first need to define the required VLANs. Take a look at the switch documentation if you don't know how, as this is outside the scope of this article.

To explain more easily, consider the following scenario:

• Both switches are connected to each other on port 1. This is only a single port that's used. LAG trunking is outside the scope of this article.
• Our fictional network has 3 VLANs: 10, 15 and 20.

This is only an example: adjust accordingly to your own situation!

Cisco

On the Cisco switch, configure the uplink port as a trunk, and, if necessary, allow the required VLANs on it. Optionally, configure STP and/or any other options, if needed:

Sw1(config)# interface Gi0/1
Sw1(config-if)# switchport mode trunk
Sw1(config-if)# switchport trunk allow vlan 10,15,20
Sw1(config-if)# no shut

If you don't want to limit VLANs on the trunk, you can omit the third statement, in which case all VLANs will be allowed to pass through the trunk.

HP

HP works differently by directly specifying VLANs on a port as tagged, untagged, or excluded:

To configure the uplink port on the HP switch, we need to emulate a trunk port by setting all allowed VLANs as tagged on that port. VLANs that are not allowed to pass through are set to excluded.

Unlike Cisco, where we work at the port level, on HP Procurve, we start at the VLAN level.

Sw2(config)#vlan 10
Sw2(Vlan-10)#tagged 1

Sw2(config)#vlan 15
Sw2(Vlan-15)#tagged 1

Sw2(config)#vlan 20
Sw2(Vlan-20)#tagged 1