Re: half-duplex
- From: Rick Jones <rick.jones2@xxxxxx>
- Date: Tue, 05 Sep 2006 22:13:37 GMT
I am running a FreeBSD 5.4 stable as a network router.
I don't know any reason why one of the ethernet ports becomes half-duplex.
Here is its detail:
em1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
options=b<RXCSUM,TXCSUM,VLAN_MTU>
inet 60.1.2.3 netmask 0xfffffffc broadcast 220.233.99.39
ether 00:04:23:bc:3a:d1
media: Ethernet autoselect (10baseT/UTP <half-duplex>)
status: active
I think someone else has suggested looking to your cables, and for a
gig-capable port to go down to 10 Megabit that sounds like sage
advice. Try, for example, to use the cable you have on em2.
You might also try connecting em1 to the same switch port as em2 as
that appears to be a "known good" port for Gigabit operation.
em2: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
options=b<RXCSUM,TXCSUM,VLAN_MTU>
inet 10.1.10.1 netmask 0xffffff00 broadcast 10.1.10.255
ether 00:04:23:bc:3a:d2
media: Ethernet autoselect (1000baseTX <full-duplex>)
status: active
This network card is a Quat Port Intel card.
Is there any way I can "reset" it to full-duplex and 1000baseT without
close down the network connection on em1?
I know I can use following command to change it:
ifconfig em1 media 100baseTX mediaopt full-duplex
but if this not work, it will close down the entire internet
connection, which I try to avoid.
Some _possibly_ useful boilerplate for duplex - it was written
initially for 100BT.
How 100Base-T Autoneg is supposed to work:
When both sides of the link are set to autoneg, they will "negotiate"
the duplex setting and select full-duplex if both sides can do
full-duplex.
If one side is hardcoded and not using autoneg, the autoneg process
will "fail" and the side trying to autoneg is required by spec to use
half-duplex mode.
If one side is using half-duplex, and the other is using full-duplex,
sorrow and woe is the usual result.
So, the following table shows what will happen given various settings
on each side:
Auto Half Full
Auto Happiness Lucky Sorrow
Half Lucky Happiness Sorrow
Full Sorrow Sorrow Happiness
Happiness means that there is a good shot of everything going well.
Lucky means that things will likely go well, but not because you did
anything correctly :) Sorrow means that there _will_ be a duplex
mis-match.
When there is a duplex mismatch, on the side running half-duplex you
will see various errors and probably a number of _LATE_ collisions
("normal" collisions don't count here). On the side running
full-duplex you will see things like FCS errors. Note that those
errors are not necessarily conclusive, they are simply indicators.
Further, it is important to keep in mind that a "clean" ping (or the
like - eg "linkloop" or default netperf TCP_RR) test result is
inconclusive here - a duplex mismatch causes lost traffic _only_ when
both sides of the link try to speak at the same time. A typical ping
test, being synchronous, one at a time request/response, never tries
to have both sides talking at the same time.
Finally, when/if you migrate to 1000Base-T, everything has to be set
to auto-neg anyway.
rick jones
--
Wisdom Teeth are impacted, people are affected by the effects of events.
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...
.
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