Subject: RE: FCIP: Comment 120

From: [email-masked]
Date: Fri, 10 May 2002 09:37:51 -0400

Ralph,

I suggest the following change, which is mostly editorial, but
may raise a different issue.  Old text:

	is the sole owner of at least one IP Address and Well Known Port 
	used to form TCP Connections

New text:

	is the sole user of at least TCP port at the IP address
	used for TCP connections to the FCIP Entity.

The editorial change is to remove any implication of sole ownership/
usership of the IP address.  The potential new issue is that while
FCIP has an IANA-assigned TCP port, the specification should not
prohibit use of a different port for initial contact.

Thanks,
--David
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From: Marinus De Jong <[email-masked]>
Date: Fri, 10 May 2002 08:07:37 -0700

David,

In the statement below can you tell me how someone would know which port 
to use for the initial contact.

>...the specification should not prohibit use of a different port for initial contact.
>
Rienco De Jong

---

From: Ralph Weber <[email-masked]>
Date: Fri, 10 May 2002 14:21:50 -0500

David,

The "one" got lost in the proposed change and I got lost over how the
sentence was supposed to end. Checkout the following:

Change:

  The FCIP Entity is the connection interface point for the IP Network
  and is the owner of the IP Address and Well Known Port used to form
  TCP Connections.

to:

  The FCIP Entity is the connection interface point for the IP Network
  and is the sole owner of at least one TCP port/IP Address combination
  used to form TCP Connections. The TCP port may be the FCIP well known
  port at a given IP Address.

Thanks.

.Ralph

---

From: "Mallikarjun C." <[email-masked]>
Date: Fri, 10 May 2002 12:56:21 -0700

> used for TCP connections to the FCIP Entity.

I'd suggest an additional tweak (since my understanding from Murali's
bullet (c) is that each Pair can avail multiple IP addresses - one per LEP).

"The FCIP Entity is the connection interface point for the IP Network 
  and is the sole user of one TCP port for each IP address used for TCP
  connections to the FCIP Entity." 

Further, I think the term "connection interface point" needs to be consistently 
used in the draft.   The last para on page 10 defines that the "connection interface point" 
is the *FCIP_DE* that's part of FCIP_LEP.  The second-to-last para on the
same page further says that FCIP_LEP is on the "line" joining FCIP Entity 
with the FC Entity - IOW, belongs to neither.

> prohibit use of a different port for initial contact.

Yes.

From Ralph:
>A new sentence can be added immediately following the sentence cited
>above to address the "why" issue.

Please do.
--
Mallikarjun

Mallikarjun Chadalapaka
Networked Storage Architecture
Network Storage Solutions Organization
Hewlett-Packard MS 5668 
Roseville CA 95747
[email-masked]

---

From: Ralph Weber <[email-masked]>
Date: Fri, 10 May 2002 18:47:50 -0500

Mallikarjun,

> Further, I think the term "connection interface point" needs to be 
> consistently used in the draft.   The last para on page 10 defines 
> that the "connection interface point" is the *FCIP_DE* that's part 
> of FCIP_LEP.  The second-to-last para on the same page further says 
> that FCIP_LEP is on the "line" joining FCIP Entity  with the FC Entity 
> - IOW, belongs to neither.

My search of the draft finds exactly one use of the phrase "connection
interface point" and that usage is in the sentence under discussion in
section 6.4 on page 12.

Looking at page 10 all I see are terms like "endpoint" and "end of
the FCIP Link". I guess there is an assumption that "endpoint" is
somehow synonymous with "connection interface point". That is not
true. The phrase "connection interface point" was chosen for the
text in page 12 because what is being discussed on page 12 is not
exactly the same thing as an "endpoint".

Consider the revised sentence again:

  "The FCIP Entity is the connection interface point for the IP Network 
  and is the sole owner of at least one TCP port/IP Address combination
  used to form TCP Connections. The TCP port may be the FCIP well
  known  port at a given IP Address."

Viewed in context, "connection interface point" is synonymous with
"the place to which TCP connect requests are directed". It is not
and is not intended to be synonymous with the endpoint of a TCP
Connection once that TCP connection is formed.

Thanks.

.Ralph

---

From: "Mallikarjun C." <[email-masked]>
Date: Fri, 10 May 2002 17:51:09 -0700

Ralph,

> somehow synonymous with "connection interface point". 

Sorry, that's what I meant though my phrasing incorrectly implied otherwise...

>That is not

This is good (but see below).

> Connection once that TCP connection is formed.

It's unclear to me how the two are different.  In all the implementations I 
had seen, your connection endpoint is where you sent the connection 
requests to - i.e. the connection interface point.....
--
Mallikarjun

Mallikarjun Chadalapaka
Networked Storage Architecture
Network Storage Solutions
Hewlett-Packard MS 5668 
Roseville CA 95747
[email-masked]

---

From: Ralph Weber <[email-masked]>
Date: Fri, 10 May 2002 21:57:02 -0500

Mallikarjun,

It looks like we are between a rock and a hard place here.

> ... In all the implementations I had seen, your connection endpoint 
> is where you sent the connection requests to - i.e. the connection 
> interface point.....

FCIP appears to be a case where everything you have ever seen is turned
on its head.

In FCIP, the FCIP Entity is the place to which TCP connect requests
are sent. When the TCP connect request arrives, the FCIP_DE does not
exist, meaning that FCIP cannot have the TCP connect requests being
directed to the FCIP_DE because it is flat out not there.

Only after a TCP connect request arrives and is validated (FSF exchange,
and possibly ASF exchange) does the FCIP_DE get created at tied to the
endpoint of the newly established TCP Connection.

Thus there is a very real difference between the TCP endpoint (which
is connected to the FCIP_DE) and the connection interface point
(which is inside the FCIP Entity).

Short of a serious FCIP rewrite (probably with major confusion added),
I do not see any way around this critical distinction.

Sorry.

.Ralph

---

From: "Mallikarjun C." <[email-masked]>
Date: Mon, 13 May 2002 10:25:16 -0700

Ralph,

> FCIP appears to be a case where everything you have ever seen is turned

Actually, the reality isn't so bad - on-the-fly instantiation of application structures
is a fact of life for most TCP listeners, for ex., iSCSI session on targets.

I think the draft is simply describing the notion of "connection interface point" from TCP's 
perspective, while describing the idea of "connection endpoint" from application (FCIP) 
perspective.

Perhaps this distinction needs to made clear in description of these ideas -
at least this wasn't obvious to me earlier.

Regards.
--
Mallikarjun

Mallikarjun Chadalapaka

---

From: "Murali Rajagopal" <[email-masked]>
Date: Mon, 13 May 2002 11:49:42 -0700

Ralph, Mallikarjun:

I would like to offer my help in resolving this issue and see if we can take
this off-line. It seems counter-productive to keep exchanging emails on this
topic with no interest from others.

-Murali

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]On Behalf Of
Mallikarjun C.
Sent: Monday, May 13, 2002 10:25 AM
To: [email-masked]; [email-masked]
Subject: Re: FCIP: Comment 120 - connection endpoint

Ralph,

> FCIP appears to be a case where everything you have ever seen is turned

Actually, the reality isn't so bad - on-the-fly instantiation of application
structures
is a fact of life for most TCP listeners, for ex., iSCSI session on targets.

I think the draft is simply describing the notion of "connection interface
point" from TCP's
perspective, while describing the idea of "connection endpoint" from
application (FCIP)
perspective.

Regards.
--
Mallikarjun

Mallikarjun Chadalapaka

---

From: Ralph Weber <[email-masked]>
Date: Mon, 13 May 2002 18:05:17 -0500

Mallikarjun,

I think we should stop worrying about what the FCIP Entity
'is' and start focusing on what it 'does'. One could argue
that taking this approach fails to address the clarity issue
you have described. But, I feel that it gets the names out
of the way and directs attention to the requirements.

With this in mind, I propose changing the sentence below
figure 4 that we have been discussing as follows.

From:

The FCIP Entity is the connection interface point for the
IP Network and is the owner of the IP Address and Well Known
Port used to form TCP Connections.

to:

The FCIP Entity receives TCP connect requests on behalf of
the FCIP_LEPs that it manages. In support of this, the FCIP
Entity is the sole owner of at least one TCP port/IP Address
combination used to form TCP Connections. The TCP port may be
the FCIP well known port at a given IP Address.

Thanks.

.Ralph

---

From: "Mallikarjun C." <[email-masked]>
Date: Mon, 13 May 2002 16:19:27 -0700

Ralph,

That sounds good.  Thanks.
--
Mallikarjun

Mallikarjun Chadalapaka