[PLUG] Network boot link died...
Mike Connors
mconnors1 at gmail.com
Wed Mar 10 10:37:24 UTC 2010
Michael Robinson wrote:
> If I understand the spec correctly for 100BaseTX, I should be fine.
> The 90' cable is labeled as outdoor Cat 5e, though I wonder how
> long is this cable going to last?
>
100 Meters [300 ft] unshielded twisted-pair cable is the "standard" for
*all* "baseband" runs. YMMV slightly depending on on cable choice [5,
5e, 6].
> I don't know what CX is and I'm not running a gigabit link, so the run
> doesn't have to work at those speeds anyways.
>
CX = coaxial cable [cable tv]
> Interestingly, turning off duplex and dropping the link speed to 10 mbps
> stabilizes the link. I noticed that duplex was set to full on the link
> and that the link was unstable with that setting.
>
f 10 Mbps half-dup works, but you can't get a stable connection that
supports auto-negotiation to a higher speed and full-dup then there are
2 things to look at.
1. The cable run.
2. The NICs
You can check for problems at both of these points by looking at
ethernet error stats w. ethtool
ethtool -S eth0
NIC statistics:
rx_errors: 0
tx_errors: 0
tx_dropped: 0
collisions: 0
rx_length_errors: 0
rx_over_errors: 0
rx_crc_errors: 0
rx_frame_errors: 0
rx_missed_errors: 0
tx_aborted_errors: 0
tx_carrier_errors: 0
tx_fifo_errors: 0
tx_heartbeat_errors: 0
tx_window_errors: 0
tx_abort_late_coll: 0
tx_deferred_ok: 0
tx_single_coll_ok: 0
tx_multi_coll_ok: 0
tx_timeout_count: 0
tx_restart_queue: 0
rx_long_length_errors: 0
rx_short_length_errors: 0
rx_align_errors: 0
tx_tcp_seg_good: 0
tx_tcp_seg_failed: 0
rx_csum_offload_errors: 0
alloc_rx_buff_failed: 0
rx_dma_failed: 0
tx_dma_failed: 0
You should be able to just ifdown then ifup the interface to clear the
counters and then watch the counters while both NICs are set to
auto-negotiation.
*The problem w. auto-neg is that not all vendors implement the standard
correctly, so many times an Intel card and D-link card may not play well
together.
If you see a lot of collisions that could mean you have a bad NIC that's
jabbering away and causing the other NIC t back-off and retransmit.
If you see carrier errors that would be more indicative of a problem w.
the cable. I don't know if this is a home-made or store bought cable.
But the other thing you could try if you have the tools and skills and
cut the ends of and re-crimp new connectors on them. *Especially if you
see the protective sheath is not inside the connector, which means the
hair-width copper wires can be easily bent and/or broken.
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