Re: [tcpm] WGLC: TCP's Reaction to Soft Errors

Mark,

On 4/11/2007 10:27 AM, Mark Allman allegedly said the following:
>>> http://www.ietf.org/internet-drafts/draft-ietf-tcpm-tcp-soft-errors-05.txt
>> Mark points out that I should mention that the last non-editorial
>> change to this draft was the addition of several omitted error codes
>> from Section 2 when the draft was revised from -04 to -05.  WGLC
>> readers should make sure that the draft does address all the codes.
> 
> I just did some diff-ing and the old and new paragraphs are appended
> below.  But, basically rev -04 covers these codes:
> 
>   ipv4 dest unreach: 0, 1, 5
>   ipv6 type 1: 0, 3
> 
> and rev -05 covers these:
> 
>   ipv4 dest unreach: 0, 1, 5
>   ipv4 time exceeded: 0, 1
>   ipv4 param problem
>   ipv6 dest unreach: 0, 3
>   ipv6 time exceeded: 0, 1
>   ipv6 param problem: 0, 1, 2
> 
> Just in terms of coverage this seems like a pretty significant change.
> 
> Fernando- Can you explain why you did this?  And, in particular, did you
> receive feedback that stacks are using this expanded list?  (This is
> targeted as an informational document about what stacks do, not as a
> standards change.)

I sent some unicast comments/questions to Fernando a few weeks ago about
soft-errors-04; the (translated) one that likely prompted this change is:

----->8-----

2. Error Handling in TCP

   The Host Requirements RFC [RFC1122] states, in section 4.2.3.9., that
   the ICMP "Destination Unreachable" messages that indicate soft errors
   are ICMP codes 0 (network unreachable), 1 (host unreachable), and 5
   (source route failed).  Even though ICMPv6 didn't exist when

###CP> Question: Is there any specific reason why you only consider
###CP> Unreach 0, 1 y 5 as soft errors? And not e.g. timeexceeded?
###CP> RFC1112 says they should be handled the same way:

http://tools.ietf.org/html/rfc1122

            o    Time Exceeded -- codes 0, 1

                 This should be handled the same way as Destination
                 Unreachable codes 0, 1, 5 (see above).

            o    Parameter Problem

                 This should be handled the same way as Destination
                 Unreachable codes 0, 1, 5 (see above).

----->8-----

Thanks,

--Carlos.

> 
> Thanks,
> allman
> 
> 
> 
> 
> 
> 
> -04:
>    The Host Requirements RFC [RFC1122] states, in section 4.2.3.9., that
>    the ICMP "Destination Unreachable" messages that indicate soft errors
>    are ICMP codes 0 (network unreachable), 1 (host unreachable), and 5
>    (source route failed).  Even though ICMPv6 didn't exist when
>    [RFC1122] was written, one could extrapolate the concept of soft
>    errors to ICMPv6 Type 1 Codes 0 (no route to destination) and 3
>    (address unreachable).
> 
> -05:
>    The Host Requirements RFC [RFC1122] states, in Section 4.2.3.9., that
>    the ICMP messages that indicate soft errors are ICMP "Destination
>    Unreachable" codes 0 (network unreachable), 1 (host unreachable), and
>    5 (source route failed), ICMP "Time Exceeded" codes 0 (time to live
>    exceeded in transit) and 1 (fragment reassembly time exceeded), and
>    ICMP "Parameter Problem".  Even though ICMPv6 didn't exist when
>    [RFC1122] was written, one could extrapolate the concept of soft
>    errors to ICMPv6 "Destination Unreachable" codes 0 (no route to
>    destination) and 3 (address unreachable), ICMPv6 "Time Exceeded"
>    codes 0 (Hop limit exceeded in transit) and 1 (Fragment reassembly
>    time exceeded), and ICMPv6 "Parameter Problem" codes 0 (Erroneous
>    header field encountered), 1 (Unrecognized Next Header type
>    encountered) and 2 (Unrecognized IPv6 option encountered).
> 
> 
> 
> 
> 
> 
> ------------------------------------------------------------------------
> 
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-- 
--Carlos Pignataro.
Escalation RTP - cisco Systems

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