Subject: Re: [tcpm] TCP soft errors draft

From: Fernando Gont <[email-masked]>
Date: Sat, 07 Oct 2006 04:13:23 -0300

At 14:17 03/10/2006, Sally Floyd wrote:

>However, it can be more complicated than that.  For example,
>Section 6.1.1.1 of  RFC 3168 (ECN) says the following:
>
>    "To provide robust connectivity even in the presence of such faulty
>    equipment, a host that receives a RST in response to the transmission
>    of an ECN-setup SYN packet MAY resend a SYN with CWR and ECE cleared.
>    This could result in a TCP connection being established without using
>    ECN."
>
>    "A host that receives no reply to an ECN-setup SYN within the normal
>    SYN retransmission timeout interval MAY resend the SYN and any
>    subsequent SYN retransmissions with CWR and ECE cleared."
>
>This is explained further in RFC 3360 on "Inappropriate TCP Resets Considered
>Harmful".  Thus, even "hard errors" are not always straightforward these days.

Do you suggest to address this in the draft? Or maybe the draft could 
just limit to handling of ICMP error messages?

Originally, the draft did not mention the handling of RST segments. 
However, in some later revision the RST-related text (less than a 
line) was included "for completeness sake", I guess.

My take is that removing that line (rather than adding text on other 
ways an RST could be handled) will keep the draft simple.

(One could also add that there are some systems that do not abort 
(not yet established) connections upon receipt of RSTs, as they could 
be an indication of a listening queue being full, rather than a TCP 
port being closed or some other hard error condition)

Thoughts?

Thanks!

--
Fernando Gont
e-mail: [email-masked] || [email-masked]
PGP Fingerprint: 7809 84F5 322E 45C7 F1C9 3945 96EE A9EF D076 FFF1

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From: Fernando Gont <[email-masked]>
Date: Sat, 07 Oct 2006 04:13:23 -0300

Thoughts?

Thanks!

---

From: Sally Floyd <[email-masked]>
Date: Sun, 8 Oct 2006 23:48:03 -0700

> just limit to handling of ICMP error messages?

Sorry, I wasn't suggesting that you add this to the draft.  Just that 
you delete or rephrase the
sentences that say that hard errors like Resets are simple and merit a 
simple
response from TCP...

- Sally
http://www.icir.org/floyd/