layer 4 switches

[Gino del Rosario]

Hello,

What is an easy way to ascertain whether a layer 4 switch is appropriate for our organization. We currently have a HP 4108 GL and are thinking of adding another. Does is make sense to link a layer 2/3 switch to a 2/3/4 with a gigabit transceiver? What would you do?

Thanks,

Gino del Rosario

[SCOOTER]

Question, what do you expect a layer 4 switch to do? And for the second question, yes it does make sence, why not.

[Gino del Rosario]

how I can be certain that we can take advantage of it? Does it make sense that I'm connecting a layer 2/3 switch to a 2/3/4?

[Arimo Laine_2]

Hi

What kind of performance do you expect from the layer 4 switch?

Arimo

[Jerome Henry]

What do you link it to ? If your prot. is TCP/IP, then layer 3 means dealing with IP adresses, which may be useful for access lists for examples or VLANS.
Else layer 2 is good & cheaper.
Layer 4 will help you deal with TCP, such managing ports stuff on access lists, once again 'for example'.
But we need to know what you intend to connect to give you intelligent advice !
Yours

[Gino del Rosario]

We are a windows shop running TCP/IP we currently have a HP4108gl as a switch. We are also using MS ISA server as a firewall. In terms of applications I can't think of any that we use that can take advantage of a layer 4 switch. I hope I'm making sense.

[Arimo Laine_2]

OK.

The question about linking switches with a GB cable/fiber:

This is purely layer2 stuff. Using a gigabit link between switches provides you more bandwidth between the devices, hence eliminates one possible bottleneck from the network. So, as Scooter said, in terms of capacity it does make sense.

As for whether or not use layer4 switch:

Traditional layer2 switches work purely on MAC addresses. Layer3 switch is a bit more complicated thing... the term is often used mainly as a sales trick for a switch that has for example capacity to prioritize traffic according to protocol. I'd say that a true layer3 switch is a device that can switch traffic by IP addressing - routing in hardware, that is. Layer4 device can also prioritize and otherwise handle traffic based on TCP ports etc.

As for your original question whether a l4 device is appropriate... I think you just answered that yourself:

"In terms of applications I can't think of any that we use that can take advantage of a layer 4 switch."

HTH,
Arimo

[Gino del Rosario]

Makes perfect sense, thanks!!