Client access to a server on one port belonging to two VLANS

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Problem:  I want to buy a Cisco 24 port switch that  has the ability to have one port that can be a member of two VLANS.  VLAN 1 will be on subnet 192.168.3.X and VLAN 2 will be on subnet 192.168.30.X.  A MS 2003 Standard server with one NIC assigned with two IP addresses will be attached to a port on the switch that belongs to both subnets.  The server's two IP addresses are and   The idea here is that all clients on either VLAN need to be able to see this server.  Does anyone know if this scenario can be done and if so how and what switch do I need?  Note:  I can't add another NIC to the server, the software I am using on the server can work with only one NIC but the multiple IP addresses on one NIC are ok though.

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manish arora Thu, 07/15/2010 - 10:01

I think the only time when a port is assigned multiple vlans is when you have the port configured as a trunk link , i have personally not configured this but i am preety sure that there are servers available in the market which are capable of interpreting vlan tagging. But yes for sure you cannot have a switchport in access mode member of multiple vlans. what i have personally done is that you can assign multiple subnets to a vlan interface using secondary command and it works fine.

server that can do vlan tagging :-

1> ibm p series ( rs600)

2> hp blade vc

hope it helps


Hmmm so it sounds like you are saying that I need to make a VLAN belong to more than one subnet instead of a port belonging

to more that one VLAN?  Also, the server needs VLAN tagging ability?  My current server NIC does not have that as an opiton.  Also, I was hoping I could leave the server alone and just get a switch that will handle what I need.  Replacing the server is not an option my company will allow.

Nagaraja Thanthry Thu, 07/15/2010 - 10:11


Does your server support VLANs? If yes, you can buy any switch that supports VLANs and dot1q trunking. Configure the port connected to the server as a trunk and let the server identify VLAN traffic and respond accordingly.

Hope this helps.



manish arora Thu, 07/15/2010 - 10:51

I just tested a linux ( redhat ) for vlan tagging with a dell switch, i works well but some performance loss as the same interface is doing processing for both vlans traffice. the server is dell rc400 and switch is dell 6248 with dot1.q tagging.

manish arora Thu, 07/15/2010 - 11:07

It depends what kind of software you are using on your server. i just

asked my system administrator and he said , he has done something similar on

linux , windows 2003/2008. just google it ..

Amit Singh Thu, 07/15/2010 - 14:18

Easiest, Put another NIC, configure it with a different Subnet ip, have each nic connected to the respective vlan and you will be good to go.

Nagaraja Thanthry Thu, 07/15/2010 - 15:52


If using only one NIC is the only option, then you can consider using a 3500XL switch (although it is obsolete and not supported any longer). 3500XL switches support multi-vlan concept where you can configure two vlans on the same interface.

Just remember that Cisco has announced that this switch is end-of-life and end-of-support. However, it does what you are looking for.

Hope this helps.




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