VLAN (dot1q) tra Cisco e switch di altri produttori

Outline: we've standardised on Cisco networking equipment for both the core of the network, and for the edge of the network. One of the reasons for using Cisco at the edge is that we had started to use inter switch links (ISL) between the core and the edge to carry different VLAN's on our network. Recently, the ISL links have been re-configured to use 802.1q standard (dot1q) for connecting together VLAN topologies. This mean's that we can start using other edge switch manufactures kit like HP, 3Com, and ATi.

This page shows the basic configurations that were used to test interoperability.

Cisco 3524 configuration: This switch was connected to the main campus switch, which provided the VLAN information. With Cisco's IOS, each physical port is configured with its required VLAN or trunk information.

interface FastEthernet0/1
switchport access vlan 120
interface FastEthernet0/2
description Connected to Test Switch
switchport trunk encapsulation dot1q
switchport mode trunk

HP Procurve 2650 configuration: With HP switches, each interface is added into the VLAN configuration. To assign a VLAN to a port, use the 'untagged ' command. To assign the VLAN to a port with it's dot1q tags, use the 'tagged ' command. Use this command on the switch port connected to the trunk port on the Cisco. In this case, port 49 is connected to the trunk port on the Cisco, and therefore, VLAN information needs to be added to the packets.

vlan 120
name "VLAN120"
untagged 1
tagged 49
exit
Status: After getting to grips with the HP's command set, the combination of Cisco and HP was fouind to interwork, with no apparent problems at all.

3Com SuperStack III 4400 configuration: The SuperStack also has a menu driven interface. Again, each interface is added into the VLAN configuration. Firstly, it is necessary to create the VLAN on the system. For example:

Select menu option (bridge/vlan): create
Select VLAN ID (2-4094)[3]: 116
Enter VLAN Name [VLAN 116]: Systems VLAN

Then an interface is added to the VLAN. Example:

Select menu option (bridge/vlan/modify): add
Select VLAN ID (1-2,116,120)[1]: 116
Select bridge ports (AL1-AL4,unit:port...,?): 1:3
Enter tag type (untagged, tagged): untag

And finally, to add the VLAN into the dot1q interface, Example:

Select menu option (bridge/vlan/modify): add
Select VLAN ID (1-2,116,120)[1]: 116
Select bridge ports (AL1-AL4,unit:port...,?): 1:1
Enter tag type (untagged,tagged): tagg

Status: Again, the combination of Cisco and 3Com was found to interwork.