VLAN interfaces on FreeBSD; performance issues

[Blake Covarrubias]

On Sep 10, 2005, at 8:37 AM, Chuck Swiger wrote:

> Blake Covarrubias wrote:
>
>> I have a question about VLAN interfaces on FreeBSD. I've read the   
>> documentation and have set them up on a machine. After doing so   
>> though the machine seems less network responsive. Does  
>> implementing  VLAN interfaces / tagging slow down network  
>> performance?
>>
>
> Some, yes, although not by much and that depends to some extent on  
> whether your NIC has VLAN_MTU hardware support.

I'm not sure if VLAN_MTU is available or enabled on my NIC. I will  
have to check that.
>
>
>> The reason for wanting VLAN tagging is the machine has once NIC  
>> and I wanted
>> to multi-home it without having to install another NIC. The  
>> network card is
>> using the 'fxp' driver.
>>
>
> fxp is a good NIC hardware.  However, if you are trying to connect  
> two distinct subnets, playing ISO layer-2 games with VLANs is not  
> going to result in a good substitute for layer-3 IP routing.
>
> You cannot truthfully multihome a machine with a single NIC.
>
My goal is to make this machine a gateway for several servers that I  
need to segment that will be on different IP subnets. I could always  
just alias the IP's to the NIC on the gateway machine, but I need  
layer-2 separation for security.  I'm doing this for co-located  
servers (hence the need for segmentation) I don't think its feasible  
to add a NIC for every new machine.

I'll check to see if VLAN_HWTAGGING and VLAN_MTU is available on the  
NIC. If anyone has any other experience in setting up a router/ 
gateway in this type of environment I'd appreciate your input.

Thanks in advance.

--
Blake Covarrubias