Subject: Re: disman issue REMOPS-1

From: [email-masked]
Date: Fri, 2 Jul 1999 03:15:10 -0400

>> I think the question Dave is raising here ("MUST NOT" vs "NOT RECOMMENDED"
>> for traceroute implementation based on ICMP) is disman issue REMOPS-2.

>Yes, sorry for crossing issues :)

REMOPS-1 was a text clarification that has been satisfied. The current text is:

     Implementations of the remote traceroute capability as defined
     within this memo MUST be done using UDP packets to a (hopefully)
     unused port.  ICMP probes (ICMP Echo Request packets) MUST NOT be
     used.  Many PC implementations of traceroute use the ICMP probe
     method, which they should not, since this implementation method has
     been known to have a high probability of failure.  Intermediate
     hops become invisible when a router either refuses to send an ICMP
     TTL expired message in response to an incoming ICMP packet or simply
     tosses ICMP echo requests altogether.

     The behavior of some routers to either not return a TTL expired
     message in response to an ICMP Echo request is due in response to
     the following text extracted from RFC792 [20]:

     "The ICMP messages typically report errors in the processing of
     datagrams.  To avoid the infinite regress of messages about messages
     etc., no ICMP messages are sent about ICMP messages."

REMOPS-1 should be closed since I added the suggested text. I have also
added some text to better (I hope) explain the restriction. REMOPS-2 addresses
the issue of not allowing use of ICMP Echo Request packets.

>> If so, can we close REMOPS-1, which was simply a question of what the
>> referent for "it" was?

>My personal opinion:

>> > Is it POSSIBLE to do a traceroute implementation which does not contain
>> > said bugs?  If so, then MUST NOT seems a bit strong to me.

>If this is the case (it is possible), then yes I agree we can close
>REMOPS-1 (and leave REMOPS-2 open).

>> > If it is NOT possible to do such an implementation, then the wording
>> > still isn't right.

>If this is the case (it's not possible), then REMOPS-1 should remain open
>since the proposed change would be incorrect.

I would like to continue the discussion under the REMOPS-2 issue and will
respond to Randy's note with respect to RFC2119 next.

Ken

---

From: Dave Thaler <[email-masked]>
Date: Fri, 2 Jul 1999 15:11:01 -0400 (EDT)

> REMOPS-1 was a text clarification that has been satisfied. The current text is:
[...]

Thanks, the new text addresses my concern nicely.
We can close REMOPS-1 as far as I am concerned.

-Dave