I'm trying to fix a very strange problem remotely on a machine at a customer site. The machine is a Dell PowerEdge 1950. The machine's NIC is a dual-port on-board Broadcom NetXtreme II BCM5708 Gigabit Ethernet, using the bnx2 driver.
The primary interface eth0 works perfectly, and is in fact how I am ssh'd in.
However, the secondary interface eth1 is not transmitting. I can see this in ifconfig output, for example, where the TX field is always 0. However, it is receiving, and tcpdump shows ARP requests coming from the ISP's gateway on the other side.
The interface is physically connected to a Siemens BSTU4 modem, configured by the ISP. The link is properly set to 10MBps and full duplex, without negotation, as the ISP requested. A small
/30 subnet is configured. For the sake of anonymity, let's say the machine is
22.214.171.124/30, and the ISP's gateway
.1. The machine has no firewall settings whatsoever.
Even running something like
arping -I eth1 126.96.36.199, and running tcpdump alongside, shows no traffic whatsoever being transmitted on the interface. (But the other side keeps steadily sending ARP requests, and that is all that can be seen.)
What could be causing this?
Here's some output, anonymized, which may hopefully help:
$ ethtool eth1 Settings for eth1: Supported ports: [ TP ] Supported link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Full Supports auto-negotiation: Yes Advertised link modes: Not reported Advertised auto-negotiation: No Speed: 10Mb/s Duplex: Full Port: Twisted Pair PHYAD: 1 Transceiver: internal Auto-negotiation: off Supports Wake-on: d Wake-on: d Link detected: yes $ ip link show eth1 3: eth1: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 1000 link/ether 00:15:c5:xx:xx:xx brd ff:ff:ff:ff:ff:ff $ ip -4 addr show eth1 3: eth1: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 1000 inet 188.8.131.52/30 brd 184.108.40.206 scope global eth1 $ ip -4 route show match 220.127.116.11/30 18.104.22.168/30 dev eth1 proto kernel scope link src 22.214.171.124 default via 10.0.0.5 dev eth0