Thank you to all who responded, especially Christopher, Jousha and Mike.
Most of you suggested checking the NIC and switchport for mismatches. 

This is a portion of "ifconfig eth0":
admin:/proc/net # ifconfig eth0
eth0      Link encap:Ethernet  HWaddr 00:90:27:B6:FB:E7  
          inet addr:172.16.2.7  Bcast:172.16.255.255  Mask:255.255.0.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:259376827 errors:0 dropped:0 overruns:0 frame:0
          TX packets:188989102 errors:0 dropped:0 overruns:0
carrier:65070
          collisions:54220248 txqueuelen:100 
          RX bytes:2574728265 (2455.4 Mb)  TX bytes:2729800656 (2603.3
Mb)

This is the system on the 100Base-T line connected directly to a Cisco
switch, which should be set at full duplex. Does the fact that they're
any collisions at all indicate that this is not working in full duplex
mode? The collisions are 21% of the number of RX packets, and 28% of the
TX packets. Are these numbers excessive?

At one time I knew of a program or command that you could run to
display the settings of the NIC, like auto-negotiate and so forth. For
the life of me I can remember it now. Any suggestions for determining
this information?

Thanks, again, for all your continued help.

-Kevin

>>> Christoph Scheeder <christoph.scheeder AT scheeder DOT de> 08/08/02
10:33AM >>>
Hi,,


KEVIN ZEMBOWER wrote:

> Hello all.
[...]


> Filesystems Dumped           19          4         15   (1:15)
> Avg Dump Rate (k/s)        42.9       43.1       30.9

                              ^^^^

this value is verry low for a 100baseT line,
many people here on the list have found after such a change in
network-infrastructure that some combinations of
switch/network-card/OS
have big problems with autonegotiating correct values for
transfer-speed
and duplex-mode resulting in heavy slow-down of network-speed.
Make shure your networkcard and your switch have negotiated correct
values.
Forcing one side to fixed values solved AFAIK all those problems.
Christoph

> 
> Tape Time (hrs:min)        1:03       1:01       0:02
> Tape Size (meg)          3284.8     3244.6       40.2
> Tape Used (%)              28.4       28.0        0.3  
(level:#disks
> ...)
> Filesystems Taped            19          4         15   (1:15)
> Avg Tp Write Rate (k/s)   887.6      906.7      328.7
> 
> Here's the only variables in the config that I think would affect
> this:
> netusage  1200 Kbps     # maximum net bandwidth for Amanda, in KB
per
> sec
> 
> Thanks for your thoughts and suggestions on this.
> 
> -Kevin Zembower
> 
> 
> -----
> E. Kevin Zembower
> Unix Administrator
> Johns Hopkins University/Center for Communications Programs
> 111 Market Place, Suite 310
> Baltimore, MD  21202
> 410-659-6139
> 
>