Trunked VLAN to a Server/host

Hello all. Can't figure out what these guys mean.

From Introduction to VLANs

"Beyond its intended purpose of configuring trunk links between switches, ISL is often used in other ways. For example, it is possible to purchase network interface cards that support ISL. If a server were configured with an ISL-capable network card, it could be connected to an ISL port on a switch. This would allow a server to be made part of multiple VLANs simultaneously, the benefit being that hosts from different broadcast domains could then ACCESS the server without the need for their packets to be routed."

From my sybex book:

"Trunking allows you to make a single port part of multiple VLANs at the same time. This
can be a real advantage. For instance, you can actually set things up to have a server in two broadcast domains simultaneously, so that your users won’t have to cross a layer 3 device (router) to log in and ACCESS it."

So, how can a host on vlan A 192.168.10.x and a host on vlan B 192.168.20.x BOTH ACCESS the server WITHOUT having to cross a router (needed for inter-vlan communication)??

Sure you can access it from vlan A if the server were 192.168.10.x, or B if 20.x, and a simple re-ip of the server would do it I guess, is this what they mean?

Thanks all!
J

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Comments

kalebksp

Some server NICs allow you to create multiple logical interfaces for a single card and assigned each a VLAN and IP address. This very similar to how router on a stick works. For example the server might have logical interface A configured to communicate on VLAN 10 with the IP 192.168.10.5 and logical interface B configured to communicate on VLAN 20 with the IP address 192.168.20.5.

You can achieve the same effect by putting multiple NICs in a server and connected each to an access port in different VLANs.

Hope this helps.

ncsugrad2002

kalebksp wrote: »

Some server NICs allow you to create multiple logical interfaces for a single card and assigned each a VLAN and IP address. This very similar to how router on a stick works. For example the server might have logical interface A configured to communicate on VLAN 10 with the IP 192.168.10.5 and logical interface B configured to communicate on VLAN 20 with the IP address 192.168.20.5.

You can achieve the same effect by putting multiple NICs in a server and connected each to an access port in different VLANs.

Hope this helps.

Basically, yep.

Also, remember that trunks get traffic from all VLAN's (well, not always, but lets keep it simple..) so if a server is connected as a trunk it can see traffic from all VLAN's.

as was said earlier, only certain network cards can do this..and it probably takes logical interfaces with addresses in each subnet/VLAN for it to actually work.

it's a very good idea though to do it that way.. so you don't always have to buy a Layer 3 switch or deal with a (typically) slow router on a stick setup

JNeko

kalebksp wrote: »

Some server NICs allow you to create multiple logical interfaces for a single card and assigned each a VLAN and IP address. This very similar to how router on a stick works. For example the server might have logical interface A configured to communicate on VLAN 10 with the IP 192.168.10.5 and logical interface B configured to communicate on VLAN 20 with the IP address 192.168.20.5.

You can achieve the same effect by putting multiple NICs in a server and connected each to an access port in different VLANs.

Hope this helps.

Thanks for the quick replies guys. The responses helped. Best of luck.
J