Re: full/half duplex problem
- From: Rick Jones <rick.jones2@xxxxxx>
- Date: Mon, 25 Sep 2006 22:35:42 GMT
cconnell_1@xxxxxxxxx wrote:
Im having a reallyt strange problem with solaris 10 update1 gb
interfaces on an ibm blade centre ls20 interfacing with the nortel
switch module. The bge interfaces by default come up as half duplex,
so I set the bge.conf as follows:
adv_autoneg_cap = 0;
That disables autoneg entirely yes? I was under the understanding
that autoneg had to be on for Gigabit.
adv_1000fdx_cap = 1;
adv_1000hdx_cap = 0;
adv_100T4_cap = 0;
adv_100fdx_cap = 0;
adv_100hdx_cap = 0;
adv_10fdx_cap = 0;
adv_10hdx_cap = 0;
adv_asym_pause_cap = 0;
adv_pause_cap = 0;
Now when I reboot the system the interfaces come up as full
duplex. (on the nortel switch side you cant change the settings)
?!?
But when I disable/reenable a port on the upper switch module the
interface bge0 strnagely comes up as half duplex, BUT if I do the
same to the lower switch module bge1, it comes up as FULL duplex!
Does this sound like a solaris bug? Both modules are same firmware
level, I thought the bge.conf should set all instances of bge the
same. Any suggestions welcome.
Quasi-random boilerplate on autoneg, written primarily in the context
of 100BT not gigabit:
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.
--
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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- From: cconnell_1
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