[ofw] enable/disable device changes IPoIB physical address??

[Jeremy Enos]

Thanks Fab... I am using Cisco hardware, and disabling both of them 
seems like it will be workable for us, but it still feels like a bit of 
a hack.  Is there no explicit query that can be made get the association 
I'm seeking?

Also... any idea why setting tcp/ip settings via the windows gui doesn't 
ever take?
thx-

    Jeremy

Fab Tillier wrote:
> Hi Jeremy,
>
> In Windows, IPoIB pretends to be a standard 802.3 NIC.  That means the
> MAC address it reports to the OS for both its local address and in any
> received ARP packets is a 6-byte MAC.  This 6-byte MAC is generated from
> the 20-byte IPoIB MAC that goes over the wire and is made up of the GID
> and QPN.  Shrinking a 20-byte space down to 6 bytes is a bit of a
> challenge.  The driver discards the QPN and the subnet prefix from the
> GID, leaving just the port GUID.  This GUID is then reduced to a 6-byte
> MAC based on the vendor ID in the first 3 bytes.  There are algorithms
> in the IPoIB driver to convert Mellanox, QLogic (ex Sliverstorm), and
> Voltaire GUIDs.  For all other types, the driver generates a locally
> administered address (LAA) which starts with 02 00 (maybe an extra 00,
> too).  The lower bytes are a simple counter that gets incremented every
> time a new LAA is generated.  Note that Cisco HCAs fall into the "all
> other types" category, as there is currently no code in the IPoIB driver
> to handle these GUIDs.
>
> When the driver first comes up, on a dual port HCA the first port gets
> 02 00 00 00 00 01, and the second 02 00 00 00 00 02.  For every received
> ARP it allocates another LAA.  If you disable the first instance (the
> one that had 02 00 00 00 00 01 assigned) and then re-enable it, it will
> get the next value.  That value depends on how many LAAs have been
> allocated, so can vary.  Note that because you have the second IPoIB
> instance (02 00 00 00 00 02) enabled, the driver stays in memory when
> you disable/enable the first.  The driver will be unloaded when the last
> instance is disabled, but not otherwise.  If you keep the second
> instance disabled, the driver will be unloaded when you disable the
> first, and when you re-enable the driver starts fresh assigning LAAs.
>
> So: disable the second instance and your script will work fine without
> the reboots.
>
> As to the other problem of assigning IP addresses I haven't seen that
> behavior so I'm useless here.
>
> Cheers,
> -Fab
>
>
>
> -----Original Message-----
> From: ofw-bounces at lists.openfabrics.org
> [mailto:ofw-bounces at lists.openfabrics.org] On Behalf Of Jeremy Enos
> Sent: Wednesday, August 01, 2007 1:16 PM
> To: ofw at lists.openfabrics.org; David A. Norris
> Subject: [ofw] enable/disable device changes IPoIB physical address??
>
> Hi-
> We're attempting to create some automated scripts to change IP settings 
> w/ IPoIB adapters, and running into some strange issues.  Thus far, 
> we've been trying to identify the correct NIC/port by the physical 
> address, which seems to be the same on all hosts.  This is fine, as we 
> were looking for a reliable way to identify the port each time.  
> However, it's *not* reliable.  For some reason, disabling and 
> re-enabling the device actually changes the physical address that 
> ipconfig reports each time.  Only a reboot of the host resets it to the 
> initial address (02-00-00-00-00-01).  We're also guessing that the phys 
> addy that gets assigned on each re-enabling of the device is based on 
> some timestamp, as the disparity between them increases when there is 
> more time between the re-enabling.  Why is this address ever changing in
>
> the first place?
>
> Environment:
> OS: Win2003 x64
> HCA:  MT25208
>
> Another explanation I'm seeking is why setting static IP info via the 
> GUI doesn't seem to take.  No errors when I hit "Ok", but when I go back
>
> to the tcp/ip settings again, it's all reset to dhcp.  Even when command
>
> line utilities like netsh are used to change the IP from the cmd line, 
> the GUI does not reflect it.  Anyone else see this?
>
> thx-
>
>     Jeremy Enos
>     NCSA
>
> _______________________________________________
> ofw mailing list
> ofw at lists.openfabrics.org
> http://lists.openfabrics.org/cgi-bin/mailman/listinfo/ofw
>