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TCP-IP Digest Vol. 2 No. 14
TCP/IP Digest Friday, 26 Aug 1983 Volume 2 : Issue 14
Today's Topics:
Thank you to TCP -- A testimonial
Questions about TCP/IP for Various UNIX Versions
4.2 BSD IEN142 Time Server Available
4.2 BSD UNIX Protocol Violation Discussion
Further Details on the MILNET/ARPANET Split
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TCP/IP Digest --- The InterNet Digest
LIMITED DISTRIBUTION
For Research Use Only --- Not for Public Distribution
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Date: 16 August 1983 17:48 EDT
From: Turkewitz@ddn1
Subject: Thank you, TCP
To: TCP-IP@brl
Dear TCP designers and implementors,
This mailing list must undoubtably be a forum for many TCP
discussions, complaints, and bugs. You have probably all heard
more than your share about how much slower TCP is than NCP. This,
however, is not one of those messages. This is a simple thank-you.
I have been working on a TCP/IP connection from Germany over
a satellite link back to the United States. Unfortunately, the
line has been pretty flakey, and we have had frequent outages.
To my amazement, however, I have found out that when we reestablish
connection, I can pick up right where I left off! We had one
outage that was about 25 minutes long. I was in the middle of
composing an electronic mail message at the time the line went down.
When it came back up, I was still in the middle of composing the
message (not even an interrupt!), and the characters that I had
typed between the time that the line went down and the time that I
noticed it was down suddenly echoed to me when the line came back up!
An associate tells me that this is due to the reliability of TCP.
Thank you TCP & all involved.
--Ken Turkewitz
[ Some hosts must have *enormous* values for the retransmit timeouts! -Mike ]
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Date: 21 Jul 1983 0906-PDT
From: MUEHLEN@sri-csl
Subject: UNIX networking
To: tcp-ip@brl
cc: muehlen@sri-csl
We want to start with networking different UNIX Systems (berkeley, bell,
xenix, munix) in a local area network (ethernet). Who has done this work
and which hardware and software can be recommended? Is there any survey
available? Is anybody using UNET or 3COM or Net/One ?
Many thanks -Heinz
[ 4.2 BSD comes with a TCP/IP that is quite good. Presently, Bell System V
does *not* support TCP/IP, but Bell Labs is working on it, under contract
to U.S. Army DARCOM. UNET software is also being used by some people, and
their latest version is reported to be useable. -Mike ]
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Date: Friday, 15 Jul 1983 14:24-PDT
To: tcp-ip@Brl
Subject: IEN142 time server/user for Berkeley VAX Unix
From: Chris Kent <decwrl!kent%Shasta@sumex-aim>
Just wanted to let the community know that I've written a network time
user/server pair for 4.1cBSD Unix. I have submitted it to Berkeley for
inclusion in 4.2, but who knows when they'll finally ship? So if people
need it, I'll be happy to send it out.
You'll have better luck mailing to me as <cak@purdue>.
Cheers,
chris
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[ The following 2 messages concern a discussion of an extention to IP which
is used by 4.2 BSD UNIX on Ethernets. Bill Shannon's comments on this
appeared in the UNIX-WIZARDS mailing list, and I enclose them here to
show some of the felings in the UNIX community. -Mike ]
Date: Saturday, 20 Aug 1983 16:17-PDT
To: tcp-ip@brl
Subject: 4.2 Berkeley Unix protocol violation
From: imagen!cpr%Shasta@su-score
I've brought this up elsewhere (Unix-Wizards), but I thought I might
mention it to the TCP/IP world directly. I'm concerned about the Berkeley
4.2 Unix TCP/IP Ethernet implementation, because this version of Unix
uses a private encapsulation protocol for IP packets on 10Mbit Ether, in
violation of the as-yet-unofficial encapsulation protocol.
In detail, the problem is that this TCP implementation uses a non-standard
(i.e., an extension of RFC 820) type of IP packet encapsulation in certain
circumstances, in an attempt at efficiency improvement (due to Unix internal
structures). This happens with no warning, and with no negotation
whatsoever with the foreign host. To the foreign host, it simply appears
that the connection is hung at the point the private encapsulation is first
used.
This ``feature'' can be turned off, if you have sources, or are willing to
patch the kernel binary image, but this seems like a big mistake on
Berkeley's part. Those people trying to supply a product speaking TCP/IP on
Ethernet to the 4.2 Unix world are thus forced to either support this
extension, or else force the site to turn it off on all their 4.2 machines.
Is there an ``official position'' on this type of encapsulation ``violation''
(admittedly by extension)? (Postel? Clark?)
/Chris Ryland, IMAGEN
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Date: 9 Aug 83 12:54:15-PDT (Tue)
To: Unix-Wizards @ Brl-Vgr
From: sun!shannon @ Ucb-Vax
Subject: Re: 4.2 TCP/IP/Ethernet trailers
Philisophically, I don't believe there is anything wrong with the
4.2 TCP/IP Ethernet code, it simply imposes another software layer
(the local net encapsulation) between IP and the Ethernet.
Practically, I think it is rather unfortunate since it destroys
compatibility with the "obvious" implementations of IP on Ethernet.
Having some way of negotiating for the use of trailers sounds nice
but it also sounds like another software layer which won't be
present in the "obvious" implementations. The same sort of problem
exists with ARP. Perhaps what is needed is a "standard" for how
to implement IP on Ethernet.
In the Sun 4.2 system we've made it easy to turn off trailers in the
driver, however ARP is mandatory. We may provide a way to "wire down"
ARP translations (however the ARP translation table is by nature a
cache and therefore small) and I guess it would also be possible
to enable trailers based on the destination address. As we start
talking to other TCP/IP/Ethernet implementations I suspect we will
have to address these problems more directly.
Bill Shannon
sun!shannon
Sun Microsystems, Inc.
------------------------------
Date: 14 Jul 1983 1742-PDT
From: NIC@sri-nic
Subject: DDN Newsletter No. 28
To: DDN-NEWS-LIST1: ;
FURTHER DETAILS ON THE MILNET/ARPANET SPLIT
Testing the Logical Split
The logical split of the existing ARPANET into the Experimental
ARPANET and the MILNET is a major change which requires substantual
testing to insure it will be accomplished as an orderly process.
ALL HOSTS AND USERS will be impacted. The ARPANET will change from one
network into two, and communications with hosts on the other net will
require a knowledge of internet procedures. MILNET hosts will use a
new network number (Network 26). (Details of procuring updated host
tables from the Network Information Center will be covered in a forth-
coming newsletter.)
The MILNET and the ARPANET will remain connected via five mail bridges
(internet gateways augmented with a load-splitting mechanism and an
access control filter). The load-splitting mechanism works as follows.
Each bridge will contain a table assigning the "default" bridge for
each host to use in sending traffic to the other network. If a host
sends a message via the wrong bridge and its default bridge is
operational, the host will receive an ICMP redirect message telling it
which alternate gateway (i.e., default bridge) to use. This mechanism
allows the five gateways to balance the internet traffic. After the
initial default assignment, if one of the bridges is found to be
carrying a disproportionate share of the load, then the host
assignment table will be modified. No changes to host software are
required. As long as a host supports ICMP, the host-to-gateway
protocol, it can make full use of the bridges without knowing its
default bridge assignment in advance.
A schedule has been developed for testing prior to the actual split.
The goals of this testing are to:
o Verify the mail bridge load-splitting mechanism and
access control filter.
o Test host TCP/IP and ICMP implementations.
o Test the entire system networkwide.
Initial testing will use the testbed environment already available at
BBN. BBN has a local ARPANET-clone network, the BBNNET (Network 8),
which is connected to the ARPANET via a gateway. During daytime hours
the BBNNET passes about 50% as much traffic as does the ARPANET, with
the existing gateway passing about 1,000,000 packets during an average
day, with about 80,000 packets per hour passing through it during peak
hours. This represents a significantly heavier load than will pass
through any of the five mail bridges, therefore the BBNNET will
provide a realistic test environment.
The testing schedule is:
15 June: Two additional gateways between the ARPANET and the BBNNET
are installed.
30 June: The gateway load-splitting mechanism is operational.
15 June to 15 August: Gateway load-splitting and routing between
the ARPANET and the BBNNET are verified.
To aid users in verifying their capabilities to communicate with the
MILNET, the first MILNET host to receive net number 26 will be a
public news host implemented on a C/70, which will allow anonymous
logins and will contain information of general interest to the
ARPANET/MILNET community.
In addition, to assist TAC users, a TACNEWS service will be provided.
By typing "@n" to the TAC, a TAC user will automatically be connected
to the public news host wherever it may exist without having to know
its actual internet address.
Following are some of the major milestones of the Split.
1 July - 1 September: The mail bridges between ARPANET and MILNET
are installed.
15 July: The C70 public news host is installed as the first host in
the MILNET COI. Also, a second MILNET interface will be
added to SRI-NIC. Host managers and technical personnel
should now try to connect to the C/70 news host via the
mail bridges in order to test their ICMP implementations.
28 July - 2 August: Network technical liaison meetings in:
Los Angeles and San Francisco, Cambridge and Washington DC
1 September - 1 October: The NIC maintains the old (ARPANET-only)
and the new (ARPANET/MILNET) host tables in parallel.
During this period MILNET hosts may voluntarily change
to Network No. 26 provided their changeover is coordinated
with the NIC to permit timely update of the official host
tables. Two full day tests will occur, during which the
network will enforce the split, and hosts must use the new
host tables.
4 October: The logical split occurs. Network IMPs will enforce the
proper COI for each host, and network addressing will be
updated to reflect the split.
1 Febuary 1984: Access control filters are implemented in the mail
bridges. Although this capability has existed for some
time, its implementation is deferred to reduce the problems
associated with the logical split on 4 October.
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END OF TCP-IP DIGEST
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