Re: 2 Network Cards

[Raquel <raquel@thericehouse.net>]

On Fri, 1 Feb 2008 22:45:30 -0500
"Douglas A. Tutty" <dtutty@porchlight.ca> wrote:

> Sure.  It would make sense if the hardware could keep up with two
> NICs going full-out, so it depends on the network speed
> (10/100/1000), the speed and quality of the NICs, and the power of
> the computer.  Either way, every packet has to go through the
> kernel and the firewall code.  I don't know which is faster.  It
> takes a monster of a box to keep a GB ethernet saturated, yet alone
> 2.
> 
> Look at it this way:
> 
> Lets say we're dealing with a 100 MB/s ethernet.  Lets say that all
> the boxes on the network are all capable of saturating their 100
> MB/s ethernet.  If all the NICs all try to talk at once, as long as
> they are talking in pairs, then the switch should handle it.  In
> this case, having two NICs in your box makes sense because, being
> two virtual boxes, it is conceivable that two different client
> boxes will want to talk to the server box at full speed, as long as
> the server box can keep 2 100 MB/s NICs well fed while doing the
> serving.  Also, as long as the switch back-plane has the
> throughput.  
> 
> Remember, a second NIC will mean twice the hardware to be
> interrupting the CPU.  
> 
> I would rather spend the money on one good NIC than two cheaper
> ones.  
> 
> Doug.

I think that I understand what you're saying.  However, what's the
difference?  If the machine is capable of handling 15 VirtualHosts
with 1 nic and 1 IP number, why can it not handle 15 VirtualHosts with
2 nics and 2 IP numbers?  What am I not understanding?

Scenario #1:
domainA and domainB are being hosted on 1 machine with 1 nic.  Out of
need, different IP numbers are needed, so eth0 is being aliased,
creating eth0:1.

Scenario #2
domainA and domainB are being hosted on 1 machine with 2 nic.  Out of
need, different IP numbers are needed, so nic#0 is eth0 and nic#1 is
eth1.

The only difference I can see is that, in essence, Scenario #1 is
possibly "throttling" what reaches the CPU by virtue of what can get
through the nic.

-- 
Raquel
============================================================
The arc of the moral universe is long, but it bends towards justice.

  --Martin Luther King, Jr.