Re: rfc 1122 and ICMP SOURCE HOST ISOLATED

Jon Postel <postel@isi.edu> Sat, 12 November 1994 01:03 UTC

Date: Fri, 11 Nov 1994 16:56:16 -0800
Sender: ietf-archive-request@IETF.CNRI.Reston.VA.US
From: Jon Postel <postel@isi.edu>
Message-Id: <199411120056.AA21711@zephyr.isi.edu>
To: Gabriel.Montenegro@eng.sun.com, braden@isi.edu
Subject: Re: rfc 1122 and ICMP SOURCE HOST ISOLATED
Cc: Steve.Drach@eng.sun.com, ietf-hosts@isi.edu, postel@isi.edu, Kent@bbn.com

Bob:

Wel, searching my archives (paper, the bits are long gone, take a moment
to remember the glorious days of TOPS-20), i find a message from Steve
Kent dated 25-Mar-82 that makes the request to establish this code.

The key passage is:

   "The host isolated message would inform the host that the 
   switch to which it is connected cannot contact the rest of 
   the network, e.g., the IMP cannot contact other IMPs or the 
   PR is not in connectivity with other PRs.  I think this can 
   be generalized to most packet switched nets and it provides 
   a useful piece of status info to the host software. (How one 
   detects this problem is, of course, net specific.)"

--jon.


   From braden@ISI.EDU Fri Nov 11 07:54:08 1994
   Date: Fri, 11 Nov 1994 07:53:12 -0800
   From: braden@ISI.EDU
   To: Braden@ISI.EDU, Gabriel.Montenegro@eng.sun.com
   Subject: Re: rfc 1122 and ICMP SOURCE HOST ISOLATED
   Cc: Steve.Drach@eng.sun.com, ietf-hosts@ISI.EDU, postel@ISI.EDU
   
   
     *> From Gabriel.Montenegro@eng.sun.com Thu Nov 10 20:40:12 1994
     *> Date: Thu, 10 Nov 1994 11:11:32 -0800 (PST)
     *> From: Gabriel Montenegro <Gabriel.Montenegro@eng.sun.com>
     *> Reply-To: Gabriel Montenegro <Gabriel.Montenegro@eng.sun.com>
     *> Subject: rfc 1122 and ICMP SOURCE HOST ISOLATED
     *> To: Braden@ISI.EDU
     *> Cc: Steve.Drach@eng.sun.com
     *> Content-Type  *> :   *> text  *> 
     *> X-Sun-Text-Type: ascii
     *> Content-Length: 929
     *> X-Lines: 22
     *> 
     *> I have a question about one of the 
     *> new ICMP destination unreachable codes
     *> defined in rfc1122. As editor of that 
     *> document, I was wondering if you could
     *> give me some information, or pointers 
     *> as to where to get it.
     *> 
     *> My question is:
     *> 
     *> 	Is destination unreachable
     *>         code 8 (source host isolated) usable as a
     *> 	"hard" error? Any info on what the 
     *>         motivation was to define this code?
     *> 
     *> RFC1122 specifies that HOST/NET 
     *> unreachable codes are "soft" errors which
     *> must be taken as hints. Codes 6-12 are 
     *> defined in that document, but nothing
     *> is said about whether they should be 
     *> considered "hard" or "soft". This omission
     *> is documented in rfc1127. 
     *> 
     *> Thanks in advance for any info you can offer,
     *> 
     *> -gabriel montenegro
     *> 
     *> Gabriel Montenegro (Nomadic Computing Group)
     *> Sun Microsystems Inc.          Email: gabriel.montenegro@Eng.Sun.COM
     *> 2550 Garcia Ave, MS UMPK14-207 Tel: (415)786-6288
     *> Mountain View, CA 94043-1100   Fax: (415)786-6447
     *> 
   
   Gabriel,
   
   I don't at the moment recall exactly what code 8 was supposed to mean
   (Jon Postel, did that come from your little list?), but it seems to be
   administrative rather than operational.  That is, it would be returned
   as a statement about the topology/configuration, not as a slightly
   stronger Unreachable.  I would therefore expect it to be "hard".
   
   I am CCing the former WG mailing list, to solicit other opinions.
   
   Bob Braden

Re: rfc 1122 and ICMP SOURCE HOST ISOLATED braden
Re: rfc 1122 and ICMP SOURCE HOST ISOLATED Jon Postel
Re: rfc 1122 and ICMP SOURCE HOST ISOLATED barns
Re: rfc 1122 and ICMP SOURCE HOST ISOLATED Gabriel Montenegro