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Vlans, Trunks and DHCP

JCRG
Occasional Contributor

Vlans, Trunks and DHCP

Hi guys,

I'm going starting implement VLANS on my office but we have some questions.

At this moment we have a HP5406zl core switch whith 4 vlans and one port TRUNK (B11). This switch have 6 mini-gbic FC ports that are connected to others switchs (HP/3COM).

The B11 port has connected to our CheckPoint FW that are configured with 2 vlans (5/6) on this interface.

All FC ports on HP5406zl switch are in VLAN6 and on others switchs that are connected to this FC ports i only can configure hosts on network of this VLAN(6).
On those switchs nothing is configured(vlans).

I want setup more 10 VLANS (100/200/300/...) on CheckPoint FW on interface that are connected to B11 port switch, what i have to do to on other switchs and on HP5406zl for i can setup this new vlans on switchs ?

It's possible on port was in more on VLAN ?

How can i setup DHCP with diferent networks on this all VLANS ?

I will upload my HP5406zl config file, and we can see we have a line on vlan (5/6) with "tagged Trk1" i don't understand why !!!!
1 REPLY
Joel Belizario
Trusted Contributor

Re: Vlans, Trunks and DHCP

You have defined port B11 as a trunk (Trk 1) so from a VLAN perspective the trunk is a member of the VLAN not the port.

If you are not aware, a trunk in HP terminology is port / link aggregation whereas in Cisco terminology tagging VLAN traffic to a port / link is called trunking.

So from a HP perspective, trunking is a separate function and has no impact on VLAN membership apart from what I described earlier.

For example, if you had setup a port trunk of two ports B1-B2 as Trk 2, you would add the trunk to the VLAN not the individual ports because the trunk is now for all purposes a single interface although with double the capacity.

The routing is being handled by the 5406 so all you need to do is ensure the links between switches are tagged members of the appropriate VLANs, just like how you have defined port B11 (Trk 1) to be members of both VLANs 5 & 6.

In each VLAN you will need to use the "ip-helper" command to define your DHCP server. Also it would be a good idea to turn on DHCP relay as well on the switch.

Good luck!