Subject: RE: [Ipoverib] IPoIB/ifconfig question

From: "Larsen, Roy K" <[email-masked]>
Date: Tue, 14 Jan 2003 10:41:23 -0800

Kanoj,

While not a draft issue, I agree that it would be nice to use this forum to
set a de facto standard for IPoIB hardware address display format.  Given
the long length, I'm inclined to go with the most condensed representation
which would be #3.  However, this does not provide a fixed length display
which is useful for scripting applications so I'm thinking a modified #2
with all fixed length numbers and a single field QPN of 0014 instead of
0:14).

Roy

-----Original Message-----
From: Kanoj Sarcar [mailto:[email-masked]]
Sent: Monday, January 13, 2003 2:35 PM
To: [email-masked]; Kanoj Sarcar
Subject: [Ipoverib] IPoIB/ifconfig question

Hi,

Here's an IPoIB implementation issue that I would
like to get feedback on from implementors. 

What should the ifconfig/arp/packet-sniffer output look like for 
the mac address part of an IPoIB interface? In the examples below, 
assume QPN=0x14, GID prefix is FE80::0 and GID suffix is 
0002c900011c9781, so that the mac address in hex is 
14FE800000000000000002c900011c9781.

Some options might be

1. 00:00:00:14:FE:80:00:00:00:00:00:00:00:02:c9:00:01:1c:97:81
(or 0:0:0:14:FE:80:0:0:0:0:0:0:0:2:c9:0:1:1c:97:81)
2. 0:14:FE80:0000:0000:0000:0002:c900:011c:9781
(or 0:14:FE80:0:0:0:2:c900:011c:9781)
3: 0:14:FE80::2:c900:011c:9781

I understand this is probably not something that should be
put into any of the I/Ds, but it would be nice if various
vendors' outputs matched. My choice is option 1, since it
is the closest to how most systems represent ethernet
addresses (except the length of course). Most systems'
"arp" command is also easily converted to handle this 
format and obviates the need for complicated parsing.

Note that the I/D 

http://www.ietf.org/internet-drafts/draft-ietf-ipoib-link-multicast-02.txt

on page 8 section 8.0 represents IBA multicast GIDs in v6 
format, I am not sure whether to suggest that the link layer 
address should also be represented similarly by network tools.

For reference, here's the ifconfig output line that prints 
mac addresses on Solaris and Linux:
Link encap:Ethernet  HWaddr 00:06:5B:4E:E4:6E
ether 8:0:20:d9:4:97

Thanks.

Kanoj
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---

From: Kanoj Sarcar <[email-masked]>
Date: Tue, 14 Jan 2003 11:00:12 -0800

> with all fixed length numbers and a single field QPN of 0014 instead of

Roy,

It was pointed out to me that 

http://www.ietf.org/internet-drafts/draft-ietf-ipoib-ibmib-tc-mib-02.txt

has

IbGuid ::= TEXTUAL-CONVENTION
     DISPLAY-HINT "1x:"
     STATUS      current
     DESCRIPTION

It would seem to me that unless there is good reason for deviation,
tcpdump/snoop/ifconfig/arp et al could just use this format (maps to
option 1).

Another reason I prefer 1 is because scripts written with the ethernet
format in mind would mostly work (if the length issues were fixed in
the script). Option 2 packs 16 bits in between each :, whereas these
ethernet based scripts pack 8 bits. 

What do you think?

The reason I went with 0:14 for the QPN (in #3) is because the QPN is 
actually 4 bytes, with the top byte set to 0. So QPN = 0x00123456 
could be a possible value (theoretically). To represent that, I would 
need to say 12:3456:... I wanted this to look the same (in terms of
number of :s) as in the case of QPN=0x00000014. Or are you suggesting
something like

4. 123456:FE80:0000:0000:0000:0002:c900:011c:9781

in this case?

Thanks.

Kanoj

---

From: Kanoj Sarcar <[email-masked]>
Date: Tue, 14 Jan 2003 11:00:12 -0800

Roy,

has

What do you think?

in this case?

Thanks.

Kanoj