From: glen@Cayman.COM (Glen B. Glater)
Newsgroups: comp.protocols.appletalk
Subject: Re: DDPChecksums problem
Date: 30 Sep 92 17:34:51 GMT
Distribution: usa
Organization: Cayman Systems Inc., Cambridge, MA
In-reply-to: cvogel@iscnvx.lmsc.lockheed.com's message of 29 Sep 92 17:41:24 GMT

In article <1992Sep29.174124.11340@iscnvx.lmsc.lockheed.com> cvogel@iscnvx.lmsc.lockheed.com (Christopher P. Vogel) writes:

  >I am running CAP 6.0 (125 patches) on a Sparc 2 (SunOS 4.1.1). The
  >S/W is configured for native EtherTalk.  I am trying to print to a 
  >LaserWriter NTR and cannot see it using atlooklws. This printer is
  >visible using Chooser.  This printer is located on the other side 
  >of a Cayman GatorBox CS. Their are other printers located in this
  >zone (IIg, NTX) which I can see using atlook as well as in 
  >Chooser.  I have already configured CAP to disable DDP checksums and 
  >am running atis with the -k option. 
  >
  >
  >
  >  _____
  > | Sun |                      -----     -------------------
  > | S-2 |                     |Gator|___| LaserWriter NTR   |
  >   ----                      | Box |   |(O84-30 Lorraine's)|
  >    |                         -----     -------------------
  >    |     Ethernet              |
  > -----------------------------------------------------------------
  >
  >
  >The GatorBox is running GatorSystem version 2.0.0 (build 1). The Firmware
  >level is 1.2. 
  >
  >1) Has anyone experienced similar problems?
  >2) Is it possible that their is a configuration problem with the GatorBox?
  >3) Does anyone have any other suggestions?
  >
  >Any help would be greatly appreciated.  Thanks in advance.

Chris:

Is the diagram above totally inclusive?  Are the Sun and the GatorBox 
actually on the same Ethernet segment?  Or is it possible that there is 
a Cisco router between the Sun and the GatorBox?  

Cisco routers also add checksums by default to packets that they create,
such as NBP lookups in response to NBP forward requests.  You can shut 
the checksum feature off in the Cisco in this manner:

Here's info on how to check a Cisco router to see if it is configured
to add checksums to packets:

  >In configuration mode on the cisco, enter the command
  >
  >---> no apple checksum
  >
  >
  >*** The above is a router configuration command. If the customer is
  >familiar with our product, the above should make sense. (to enter
  >configuration mode, type 'configure terminal' from the '#' prompt)
  >
  >If it does not, please have them call us, as there are pitfalls that
  >are too lengthy to go into via e-mail.
  >
  >If the customer would like to determine if checksums are being
  >calculated, the EXEC command 'sho apple global' will give that
  >information. Here is a sample display:
  >
  >R3#sho apple global
  >
  >AppleTalk global information:
  >  Internet is incompatible with older, AT Phase1, routers.
  >  There are 3 routes in the internet.
  >  There are 4 zones defined.
  >  All significant events will be logged.
  >  ZIP resends queries every 10 seconds.
  >  RTMP updates are sent every 10 seconds.
  >  RTMP entries are considered BAD after 20 seconds.
  >  RTMP entries are discarded after 60 seconds.
  >  AARP probe retransmit count: 10, interval: 200.
  >  AARP request retransmit count: 5, interval: 1000.
  >  DDP datagrams will be checksummed.
  >  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  >  RTMP datagrams will be strictly checked.
  >  RTMP routes may not be propogated without zones.
  >  Alternate node address format will not be displayed.
  >  Access control of any networks of a zone hides the zone.
  > 
  >
  >It would show: "DDP datagrams will not be checksummed" if it was
  >disabled.
  >
  >It is on by default. If the customer enters the command 'no apple
  >checksum' into the configuration of the router, it will also be
  >visible when the customer executes the EXEC command 'write terminal'

I hope that this helps.

Glen
--

	*************************************************************
	Glen B. Glater				Phone: (617) 494-1999         
	Technical Support Engineer		Fax:   (617) 494-5167         
	Cayman Systems Inc.			Internet: glen@cayman.com     
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