Number: 484

Date:  3-Apr-84 17':41':45

Submitter: Sannella.PA

Source: kiewiet.PASA (obrien@Rand-Unix)

Subject: Document how Dolphins determine net number; get net number off switches

Assigned To: 

Attn: vanMelle.pa

Status: Open

In/By: 

Problem Type: Documentation

Impact: Annoying

Difficulty: 

Frequency: Everytime

Priority: Unlikely

System: Communications

Subsystem: PUP Protocols

Machine: 1100

Disk: 

Lisp Version: 

Source Files: 

Microcode Version: 

Memory Size: 

File Server: 

Server Software Version: 

Disposition: '
["masinter" " 4-Sep-84 14':51':17" Source': Subject':]

Description: '
Received': from SUMEX-AIM.ARPA by PARC-MAXC.ARPA; 15 MAR 84 10':39':54 PST'
Return-path': <@SUMEX-AIM.ARPA':kiewiet.PASA@PARC-MAXC.ARPA>'
Redistributed': Xerox1100UsersGroup↑.PA'
Received': from PARC-MAXC.ARPA by SUMEX-AIM.ARPA with TCP; Thu 15 Mar 84 10':02':43-PST'
Date': Thu, 15 Mar 84 10':00 PST'
From': kiewiet.PASA'
Subject': How do Dolphins determine net number?'
To': obrien@Rand-Unix.ARPA'
cc': 1100Support.PASA, 1100users@SUMEX-AIM.ARPA'
'
The Dolphin believes the network number that it is addressed by in any'
packet it receives that it solicited (or is interested in, e.g.,'
broadcast routing packets).  In particular, if it asked for the time and'
got back a packet that addressed it by the correct net number, it would'
believe it.  You say the reply has the correct net & host numbers, but'
did you mean correct in the source or in the destination fields?  It is'
possible that your time server is simply "turning around" the request'
packet, but not filling in the unknown fields.  For example, the request'
would have had Source address = 0#xxx#yyy; simply turning that around'
would produce a reply with Destination address = 0#xxx#yyy instead of'
21#xxx#yyy.'
'
The standard practice of most low-level pup software is to fill in such'
unknown fields (if the recipient knows them) before passing the packet'
on to higher-level software.  If this were done in the time server case,'
then when the server swapped the source and destination addresses, the'
net number would have gotten filled in correctly.'
'
If this is not the problem, we''d need more information.  In particular,'
you say only that your Dolphin Alto exec didn''t know the net number.'
Did Lisp?'
'
Problem reports are seen more quickly by 1100Support if you send your'
query directly to us at 1100Support.pasa@Parc-maxc, rather than to'
1100users@SUMEX-AIM.ARPA.'
'
-----'
'
Received': from SUMEX-AIM.ARPA by PARC-MAXC.ARPA; 15 MAR 84 11':45':23 PST'
Return-path': <@SUMEX-AIM.ARPA':obrien@rand-unix>'
Redistributed': Xerox1100UsersGroup↑.PA'
Received': from rand-unix by SUMEX-AIM.ARPA with TCP; Thu 15 Mar 84 10':48':20-PST'
Date': Thu, 15 Mar 84 10':46 PST'
To': kiewiet.PASA'
Cc': 1100Support.PASA, 1100users@SUMEX-AIM.ARPA'
Subject': Re': How do Dolphins determine net number?'
In-reply-to': Your message of Thu, 15 Mar 84 10':00 PST.'
From': obrien@Rand-Unix.ARPA (Michael←OBrien)'
'
	Thanks very much for your input.  In fact someone else on the net'
sent me the same info a few days after I posted my original message.  I'
modified the turnaround routine in the manner you suggest and all our'
Dolphins now know their correct net number (wouldn''t it be nice if they'
could just get it off the D0EN2 board, where it''s set in switches?).'


Workaround: 

Test Case: 

Edit-By: masinter

Edit-Date:  4-Sep-84 14':51':19