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

richard · ‎07-15-2010

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 192.168.3.10 and 192.168.30.10. 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.

manish arora · ‎07-15-2010

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

Manish

richard · ‎07-15-2010

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 · ‎07-15-2010

Hello,

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.

Regards,

NT

richard · ‎07-15-2010

Perhaps I need to learn morea about 802.1Q. Is this just a function of the swith's ability and the server's NIC ability or does the server also need to have something else to make it support VLANS and 802.1Q?

manish arora · ‎07-15-2010

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.

richard · ‎07-15-2010

Thanks. I'm glad to know if can work. It sounds like I need to use VLAN tagging and need a server that is capable of this. To be sure, how do I determine if my server can doo this?

manish arora · ‎07-15-2010

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 · ‎07-15-2010

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.

richard · ‎07-15-2010

I would install a second NIC but the application I run on that server will not see the other NIC. The Microsoft OS does just fine but the application locks onto the MAC of NIC1 and ignores the other. This prevents me from using two NICS which I agree would be the simplest solution.

Nagaraja Thanthry · ‎07-15-2010

Hello,

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.

http://www.cisco.com/en/US/docs/switches/lan/catalyst2900xl_3500xl/release12.0_5_wc3/swg/Swgvlans.html#wp1028684

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.

Regards,

NT