[Info-vax] DE500 and autonegotiation

[Hans Bachner]

Phillip Helbig---undress to reply <helbig at astro.multiCLOTHESvax.de> 
wrote:

> In article <dKhFs.850921$%Q3.536864 at en-nntp-15.dc1.easynews.com>,
> lederman at Encompasserve.org (B. Z. Lederman) writes: 
> 
>> When I worked in OpenVMS engineering, I had a problem with an Alpha
>> and one of the earlier PCI interfaces.  I consulted with >>> THE <<<
>> expert, and was told that, after it was implemented, some
>> deficiencies were found in the 100BaseT autonegotiation protocols. 
>> Usually it worked, but sometimes it didn't depending on which NIC you
>> had and which Router / Hub / Switch it was connecting to.  The
>> solution most of the time was to either change the network equipment
>> (if possible), or, on a VMS system, use the options that enable you
>> to specify the settings the NIC should use and not autonegotiate.
> 
> From VMS or from the console.  If the former, should I worry about 
> screwing something up, or can the worse that can happen be a forced 
> reboot?

For trying, it does not matter. Either use EWx0_MODE on the console (the 
SET command won't let you use invalid values for this variable), or use 
LANCP once VMS is running. If you run into problems, shut down and 
return to the original settings. Neither variant makes permanent changes 
to the card.

In a stable 10/100 environment (with manageable switches), I'd recommend 
to use fixed settings on both ends and avoid auto-negotiation. If you 
frequently reconfigure your topology and plug all kinds of equipment 
into the same switch port over time, auto-negotiation is easier to use, 
of course.

As far as I can remember (that's all a couple of weeks away...), the 
DE500-XA was built when the autonegotiation protocol was not yet final, 
still in a draft state. And after that there were minor modifications. 
Depending on the hub/switch the DE500-XA was connected to negotiation 
worked od didn't. The later versions (-AA, -BA) were better in this 
respect. Neither of them was able to work at gigabit speed, though.

Btw, I believe all -BA cards are identified as DE504 (quad port) cards 
by $getdvi, even if they are single-port DE500s - so don't get confused 
:-)

Hans.