Multiple ethernet cards to increase server speed?

I'm running various server programs on a PC running Fedora on a LAN
behind a Belkin router. I'm interested in installing additional
ethernet cards in the box to increase connection speed on the LAN, is
this possible and/or realistic? Some of the server programs are meant
for external access (web, ftp, mail, etc), some are just meant for
internal (file server) access. I suppose I may not be able to increase
speed for external access because the connection to the modem will be
the bottleneck, and that's fine, but could additional cards speed up
traffic to/from the server on the LAN?

If anyone has any insight or advice on this, I'd appreciate it.
Thanks

-Brian

bmearns <(E-Mail Removed)> wrote:
> I'm running various server programs on a PC running Fedora on a LAN
> behind a Belkin router. I'm interested in installing additional
> ethernet cards in the box to increase connection speed on the LAN,
> is this possible and/or realistic? Some of the server programs are
> meant for external access (web, ftp, mail, etc), some are just meant
> for internal (file server) access. I suppose I may not be able to
> increase speed for external access because the connection to the
> modem will be the bottleneck, and that's fine, but could additional
> cards speed up traffic to/from the server on the LAN?

Unless you are already at Gigabit behind your Belkin, or are
particularly cash strapped, you are probably better-off just upgrading
things to Gigabit Ethernet rather than trying to juggle multiple NICs.

rick jones
--
a wide gulf separates "what if" from "if only"
these opinions are mine, all mine; HP might not want them anyway...
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

On Wed, 15 May 2007, bmearns wrote:
> I'm running various server programs on a PC running Fedora on a LAN
> behind a Belkin router. I'm interested in installing additional
> ethernet cards in the box to increase connection speed on the LAN, is
> this possible and/or realistic? Some of the server programs are meant
> for external access (web, ftp, mail, etc), some are just meant for
> internal (file server) access. I suppose I may not be able to increase
> speed for external access because the connection to the modem will be
> the bottleneck, and that's fine, but could additional cards speed up
> traffic to/from the server on the LAN?
>
> If anyone has any insight or advice on this, I'd appreciate it.
> Thanks
>
> -Brian

If you can assign different IP addresses to your internal
and external facing applications, you can split traffic
between two ethernet cards by that differentiation. You
might need two IP addresses from different subnets, or your
default route will only make use of one interface for
outgoing traffic.

On the other hand, another method to use multiple ethernet
cards is through bonding. You also need bonding support
from the ethernet switch.

If your ethernet switch (and cable to your PC) supports Giga
bit rate, one easier way maybe just to put a GbE card into
your PC.

My 2 cents.

Stephen Wong @ Hong Kong.

bmearns wrote:

> I'm running various server programs on a PC running Fedora on a LAN
> behind a Belkin router. I'm interested in installing additional
> ethernet cards in the box to increase connection speed on the LAN, is
> this possible and/or realistic? Some of the server programs are meant
> for external access (web, ftp, mail, etc), some are just meant for
> internal (file server) access. I suppose I may not be able to increase
> speed for external access because the connection to the modem will be
> the bottleneck, and that's fine, but could additional cards speed up
> traffic to/from the server on the LAN?
>
> If anyone has any insight or advice on this, I'd appreciate it.
> Thanks
>
> -Brian

Unlikely in your case.

There is a technique known as bonding where multiple ethernet links are
aggregated. It needs support from the switch as well as linux. I have
employed it with success to get a 2Gbit/sec link to an Extreme Networks
Summit, which itself had a 10gig uplink to the core switch.

Cheap Belkin switches will not have the necessary support to handle this.
You could try, but what will happen is that linux will throw packets out on
both ethernet links, but return packets will all get stuffed down one.
Probably confuse the arp cache on the others computers too.

Assuming your system is gigabit throughout:

You would (if you haven't) get more benefit from putting decent NICs in the
server and all the hosts (eg Intel, or even better, but expensive, Intel
server class NICs). Cheap NIC chips (Marvell, Broadcomm, Realtek) tend to
max out at 400-600 Mbit/sec IME. This assumes also that the bus in your
server can cope with even feeding gig, while doing everything else.

You might be surprised, but in my experiments, I was using a twin Xeon
server with 10GB RAM (ie all my active files were in cache), 4 port Intel
server class NIC, server had multiple PCI busses, so source of data (Fiber
Channel RAID array) was on a different bus. At 2gig, the Xeons were maxed
out in kernel space handling the interrupts and NFS. That was after tuning
the beast. I was going for 4gig, but I quit at 2. Opterons might have
worked better, but 2 was good enough so I left it at that.

If you describe your hardware I might be able to offer some more
constructive advice.

HTH

Tim

On Wed, 16 May 2007 04:38:56 +0800 Stephen SM WONG <(E-Mail Removed)> wrote:
| On Wed, 15 May 2007, bmearns wrote:
|> I'm running various server programs on a PC running Fedora on a LAN
|> behind a Belkin router. I'm interested in installing additional
|> ethernet cards in the box to increase connection speed on the LAN, is
|> this possible and/or realistic? Some of the server programs are meant
|> for external access (web, ftp, mail, etc), some are just meant for
|> internal (file server) access. I suppose I may not be able to increase
|> speed for external access because the connection to the modem will be
|> the bottleneck, and that's fine, but could additional cards speed up
|> traffic to/from the server on the LAN?
|>
|> If anyone has any insight or advice on this, I'd appreciate it.
|> Thanks
|>
|> -Brian
|
| If you can assign different IP addresses to your internal
| and external facing applications, you can split traffic
| between two ethernet cards by that differentiation. You
| might need two IP addresses from different subnets, or your
| default route will only make use of one interface for
| outgoing traffic.

Make that different SUBNETS, not just different IP addresses. Private
IP address ranges can be used for the internal traffic.

--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / spamtrap-2007-05-16-(E-Mail Removed) |
|------------------------------------/-------------------------------------|

Thank you all for the insight, it was incredibly informative. From all
the information you've provided, it sounds like my best best is to
simply invest in better hardware, not more hardware. Thank you all.

On 16 May 2007 14:53:25 -0700 bmearns <(E-Mail Removed)> wrote:

| Thank you all for the insight, it was incredibly informative. From all
| the information you've provided, it sounds like my best best is to
| simply invest in better hardware, not more hardware. Thank you all.

Better hardware can help. More hardware can help, too (if it's not bad
hardware). But not all choices work out well for all cases. More is
often better when you can use more in redundant modes. For example two
ethernets might be better if there is a risk of one failing that is not
diminished by having better (in the faster sense).

--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / spamtrap-2007-05-16-(E-Mail Removed) |
|------------------------------------/-------------------------------------|