[Freeipmi-devel] Re: [llnl-devel] Re: power control and BMC configuration problem

[Albert Chu]

> BMC does not respond to ARP queries after OS takes over. When OS stops
> responding to ARP requests, switch has no way to associate a MAC
> address to a port. 

My debugging has shown that tiger4 BMCs never respond to ARP requests. 
When I tried to enable "BMC-generated ARP responses", the BMC gave me
"invalid configuration option" errors.  My belief is that tiger4 BMCs
only send out gratuitous ARPs, and it is the job of the
switch/router/ethernet to see the gratuitous ARPs and cache the MAC
address of the card.

> Questions:
> Don't these switches cache the association?

I'm not 100% sure.  I do know that after we halt a machine, the ARP
cache entries in various thunder nodes are still up to date (seen
through /sbin/arp -a) ...

Al

--
Albert Chu
address@hidden
Lawrence Livermore National Laboratory

----- Original Message -----
From: Anand Babu <address@hidden>
Date: Thursday, January 22, 2004 2:45 pm
Subject: Re: [llnl-devel] Re: power control and BMC configuration problem

> Hi Al,
> 
> I am no switch expert, just theoretical guess.
> 
> Condition to reproduce:
> - when kernel halts but system is ON.
> 
> Crossover cable works: (reason)
> - because it is point to point. Any packet you drop on the network
> reaches the other end and BMC responds. (no switching or routing)
> 
> Cause of problem:
> BMC does not respond to ARP queries after OS takes over. When OS stops
> responding to ARP requests, switch has no way to associate a MAC
> address to a port. 
> 
> Debug:
> Cisco switch - Manually associate a MAC address to port
> 
> Questions:
> Don't these switches cache the association?
> 
> -ab
> 
> >We tried the cross-over cable, and power control worked perfectly. 
> So
> >its most likely some type of switch issue.  Have you been able to
> >reproduce the problem??
> 
> 
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