Subject: [Ipoverib] Comments on the latest IPoIB-CM draft

From: "H.K. Jerry Chu" <[email-masked]>
Date: Tue, 18 Oct 2005 11:11:04 -0700 (PDT)

Vivek,

The following is a list of my comments on
draft-ietf-ipoib-connected-mode-01.txt, many are editorial.

1) Line 27
"Internet- Drafts" =>
"Internet-Drafts".

2) Line 48
"This document specifies a method" =>
"This document specifies an optional method"

Suggest to spell out the "optional" part up front.

3) Line 92
Remove the non-ASCII character.

4) Various places in the draft has paragraphs describing IPoIB-CM
as if it were an independent transport mechansim for IPoIB that
is separate from IPoIB-UD. If the draft simply states upfront that
IPoIB-CM is an extension (or add-on) to IPoIB-UD, many paragraphs
become redudant and can be removed. E.g. paragraphs beginning at
line 161, section 2.1, most of sec 2.2. Line 313 to 319, 516-518,
...etc.

5) <nit> The first five lines of 2.2 may give an impression that
one QP may be used to connect to all remote nodes.

6) Continue from 4) and 5) above, sections 2.2 and 2.3 may be
combined as follows.

Every IPoIB-CM interface MUST have two sets of QPs associated with it:

        1) An unreliable datagram mode QP
        2) one or more connected mode QPs

[IPoIB_UD] describes how a node can obtain 1) and, through the address
resolution procedure, a remote node's link-layer address. Once the
latter is known, an IB connection must be setup between the nodes
before any IP communication may occur over an IB connected transport.

[continue from line 226.]

7) Line 291, why not simply say the QPN is the same as the one from
[IPoIB-UD] to avoid any confusion?

8) Line 350, change
"The IB connection is setup using the Service-ID as defined above."
to
"The IB connection is setup using the Service-ID as defined in 3.5
below."

9) Line 317 contains garbled characters (looks like apostrophe), so
does line 331, 373, 375, 377, 386.

10) Line 377, 378
QP => QPN

11) Line 383 change
"To ensure that two IB connections are not setup between the peers"
=>
"To ensure that two IB connections are not setup between the peers
due to REQ crossing"

12) [nit] Section 3.3 should spell out how to numerically compare 20
byte link-layer address.

13) Section 3.4, add a stronger statement
"IB connections created though IPoIB-CM are considered part of
an IPoIB-CM interface. As such, they SHOULD be torn down when an
IPoIB-CM interface is torn down.

14) Section 3.5 the paragraph
"The Reserved fields MUST be transmitted as zeroes. It is
dependent on the CM to ignore or check for zeroes in the
Reserved fields. This is because some implementations of CMs
require all ServiceIDs to be explicitly specified and cannot
listen to a range of values."
sounds awkward. If we allow implementations to either check for
zeros or ignore on the listening side, we might as well not to say
nothing.

15) Section 4.0
Do we expect ARP/RARP to be sent through IB connections ever?
If not it should say so in section 7.0 and remove ARP/RARP from
the table to avoid any confusion.

16) Section 7.0
Need to clarify ARP/RARP over IB connections. E.g., ARP reply
is unicast. Can it be sent back through an IB connection? (Suggest
no.)

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---

From: Vivek Kashyap <[email-masked]>
Date: Tue, 18 Oct 2005 23:24:12 -0700 (PDT)

> Vivek,

Jerry,

Thanks for the detailed comments. I'll incorporate and resend the draft.
Some responses below.

> draft-ietf-ipoib-connected-mode-01.txt, many are editorial.

yep

> Suggest to spell out the "optional" part up front.

ok

> Remove the non-ASCII character.

Puzzling. Am using text editor on Linux (vi) and
nroff. Will remove it.

> line 161, section 2.1, most of sec 2.2. Line 313 to 319, 516-518,

The idea is to delineate the differences between the option -CM and
the required -UD mode. However, I'll relook at the wording.

> one QP may be used to connect to all remote nodes.

ok..will make that clearer.

> [continue from line 226.]

agreed..though one reason for going into more detail is to make sure
the whole process is understood w/o any ambiguity.

> [IPoIB-UD] to avoid any confusion?

ok..

> "The IB connection is setup using the Service-ID as defined in 3.5

ok

> does line 331, 373, 375, 377, 386.

must be character set problem...need to verify and fix.

> QP => QPN

ok

> "To ensure that two IB connections are not setup between the peers

ok

> 12) [nit] Section 3.3 should spell out how to numerically compare 20

ok

> IPoIB-CM interface is torn down.

yes, good suggestion.

> zeros or ignore on the listening side, we might as well not to say

ok..

> the table to avoid any confusion.

ok..will remove.

> is unicast. Can it be sent back through an IB connection? (Suggest

will do. yes, agree on the 'no'.

Vivek