[linux] RHEL/CentOS 4 networking trouble

[Jonathan Nicol]

(Sorry for the cross-post, I'm under the impression that the RHEL list  
has not many members. Please let me know if I shouldn't do this.)

The boxen I'm currently working on are CentOS 4.5, I've encountered  
this same problem in RHEL 4 (no suprise, they're basically the same  
thing). They're identical hardware, with a pair of onboard NICs each,  
using the e1000 driver.

What I'm trying to do is add an IP address to eth1. These are new  
servers, eth1 has never previously been configured or even brought up.  
After adding the IP, everything looks fine in ifconfig and the routing  
table. However, the system refuses to send ANY traffic via eth1. Pings  
result in "destination host unreachable". Arping does nothing. Using  
tcpdump, I can see that ARP requests are not being sent. The ifconfig  
TX counter shows 0, and the RX counter only shows the 49 broadcast  
packets that came in while the device was in promiscuous mode (while  
running tcpdump). The mac-address-table on the switch also does not  
show eth1's MAC address, indicating it has not received a single  
packet from the server.

I've tried this on two seperate boxes. The first one, I edited the  
configuration file appropriately, and then ran 'ifup eth1' (the  
"Redhat" way).
The second one, I used 'ifconfig eth1 10.254.250.227 netmask  
255.255.255.224'. Same results.

Has anyone run into this? Any ideas on how to debug this further, and  
maybe even get it to work?

eth1      Link encap:Ethernet  HWaddr 00:30:48:8E:B4:5D
           inet addr:10.254.250.226  Bcast:10.254.250.255  Mask:255.255.255.224
           inet6 addr: fe80::230:48ff:fe8e:b45d/64 Scope:Link
           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
           RX packets:49 errors:0 dropped:0 overruns:0 frame:0
           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:100
           RX bytes:3493 (3.4 KiB)  TX bytes:0 (0.0 b)
           Base address:0x6000 Memory:e0400000-e0420000

]# mii-tool
eth0: negotiated 100baseTx-FD, link ok
eth1: negotiated 100baseTx-FD, link ok


Much thanks,

Jonathan