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multiple vlans

graham kirk_1
Occasional Visitor

multiple vlans

Is it possible for a 25xx switch to have one port with two vlans associated with it but no routing between the vlans?
4 REPLIES
Terhorst
Trusted Contributor

Re: multiple vlans

Hi Graham,

2 vlan's on one port implicates that it is a trunk port. You don't have to route between the Vlan's, but the other site should understand the tagged traffic from the trunk port.

Regards,
Alexander
Arnaud_9
Valued Contributor

Re: multiple vlans

Hi,
With HP 2524, you cannot use Vlan to do that. The only way to get something like that is to use the "Isolated Port Groups" feature.
It should work fine with one switch. If you have many switches, it may be more difficult : There is no Vlan concept in this feature, so there is no way to keep the group number from one switch to another.
One more restriction if you use it : you cannot have Vlan on the switch.
Look at this Release Note, page 13 :
ftp://ftp.hp.com/pub/networking/software/59903102-e3.pdf
Read carefully for other restrictions.

Nortel Baystacks, and maybe BPS are able to do this with VLAN.

Arnaud
Gerhard Roets
Esteemed Contributor

Re: multiple vlans

Hi Graham

If the 25xx supports vlans ... You can set those ports up as using 802.1q trunking ports. Just be sure that the device on the other end of the port can de-encapsulate it and it should be fine.

They do not need to be routed in that case.

What are you planning to attach to the other end ?

Regards
Gerhard
Bill Costigan
Honored Contributor

Re: multiple vlans

From the 25xx configuration guide...

"By default, the Series 2500 switches are 802.1Q VLAN enabled and allow up
to 30 port-based VLANs (default: 8). For information on GVRP, see â GVRPâ on
page 9-77. (The 802.1Q compatibility enables you to assign each switch port
to multiple VLANs, if needed, and the port-based nature of the configuration
allows interoperation with older switches that require a separate port for each
VLAN.)"

Basically each vlan has a tag number associated with it. The switch looks at the tag to determine to which VLAN it belongs. There is also a default so that any packet without a tag is assumed to be in that vlan. vlans can span switches but the tag assignments must be consistent between the swi