SYMALG@YUSOL.BITNET.UUCP (11/22/86)
First of all I would like to thank all the people who took the time to
reply to my request for information on Encore and Bridge. The speed and
uniformaly high technical content of the replies was simply amazing.
My sincerest thanks goes out to:
chris@columbia.edu
ROODE%BIONET@SUMEX-AIM
dudek%endor@harvunxt
hedrick@topaz.rutgers.edu
swb@devvax.tn.cornell.edu
steve%umnd-cs-gw%umn-dulu
kincl%hplnmk@hplabs.HP.CO
lars@acc.arpa
SATZ@Sierra.Stanford.EDU
weinberg%necis.UUCP@harvu
ihnp4!uokmax!mike
ott!encore!pinocchio!alan
eismo!mcvax!daimi!pederch
Editing of a summary always makes it possible to have missrepresented what
others meant to say - the responsibilty is mine alone. Sorry for the length of
the posting, but there was so much *good* info that I thought I'd let you
decide how much you were up to reading.
In a one line summary:
Encore wins especially for Unix systems, but also check out Cisco.
Original-posting:
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Newsgroups: mod.protocols.tcp-ip
Subject: Encore Annex or Bridge Terminal Server
We have a Sun 160 to which we would like to add about 10 terminals lines.
The Sun is mainly a file server for 3 3/50's, and the amount of use of
the terminal ports is expected to be light. There are other machines on the
Ethernet that I would like to reach with the terminals, but I could always
log into the Sun first, and then Telnet or whatever across the ethernet.
1) What do I lose by putting my terminals on the ethernet? For example,
will ^O ^S ^Q all get gobbled rather than passed to Emacs for instance.
Will a terminal server on the ethernet affect paging from the Sun 50's to
the Sun 160?
2) Besides flexibilty, what do I gain by having my terminals on the
ethernet? Performance? Would I be better off with an ALM on the VME bus?
3) What advantages does the Encore Annex have over the Bridge boxes?
I would love to hear from anyone who has one.
4) Does anyone have the phone number for Encore? I have the Bridge info.
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Selected comments to highlight the major points:
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We 3 Bridge CS/1T terminal servers with 96 lines attached. We are not
particularly happy with the software support; in particular, the boxes
are memory-starved and inefficient due to some fundamental design limitation
that restricts the box to using very small packets (default 82 bytes, and
this is a max for some of their boxes).
You might want to check out Cisco Systems's ASM, which is probably the
best-performing and cheapest box you'll find. The company is tiny and in its
infancy, but the guy maintaining the software is really sharp. I don't have
any of their boxes, but I've played with them a little and read their
documentation and I'd buy some if we had the money. Their number in Menlo Park
is (415) 326-1941. I think an 8-line box with a parallel printer port is only
around $7K, and you can expand it in 8-line increments up to 48 lines or so, or
add additional network interfaces to use it as a gateway.
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You should consider that you would be better off if those people
desiring terminal access to a Sun went not to a file server
but rather to one of the clients (preferably one not then in use).
To have a couple users on the file server can degrade performance for
the clients more so than adding those same users on clients.
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We looked
closely at Encore and Bridge before deciding to go with Encore.
The advantages that Bridge had was that they were slightly cheaper per port,
and they supported connections from a host to a remote Bridge port, to operate
modems and in general bridge from a terminal on the ethernet to an
arbitrary RS232 connection. Encore had a more familiar user interface
(mimics UNIX BSD commands rlogin, telnet, csh job control), the software
was downloaded from a central host instead of distributed on floppies,
and in general Encore seemed to have more of a commitment to the UNIX/TCP-IP
world than Bridge (Bridge started their terminal servers with XNS).
The ability of the Encore Annex boxes to offload some of the terminal i/o
load from the host by running an Encore-modified version of GNU-Emacs
clinched it for us.
We have been *very* satisfied with the Encore Annex terminal servers.
We now have 6, and I anticipate getting at least 2 more before the end
of the year. Encore has certainly shown a commitment to UNIX and the
TCP world - they anticipate support of BSD 4.3 based TCP/IP in their
servers (including subnet support), and ARPA domain-server support in
their next release (it will be in beta test soon). We have not had a hardware
failure since we got them (only a couple of months, but still a good sign).
They have responded to complaints of bugs with rapid software updates which
correct the problems. The technical assistance I have received over the
telephone was knowledgeable and helpful.
Performance-wise, the cost of rlogin connections to the SUN is certainly
worse than a direct serial connection - on the order of twice as cpu-intensive.
The ability of SUNs to push bytes out their ethernet controllers is very good,
so this isn't as much of a problem as it could be. We are pushing this to
the limit, and though the machine still behaves pretty well and services NFS
disk requests without many problems, the interactive-echo response to users
sometimes suffers. Part of a solution to this problem is to implement
the NVS and NVT kernel enhancements from rick@nyit, which effectively connects
the incoming TCP socket with the input/output of the pseudo-tty which the
rlogin is using (instead of passing all input and output through rlogind).
It sounds to me like your configuration won't be pushing things too hard,
so you could probably get away without this. I am hoping SUN will support
such mods in future releases of their OS - I have mentioned this to them,
but I have no idea whether they will or not.
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At some point terminal service will put a load on your Ethernet. But
that point is several thousand users.
If your system is going to be used for heavy timesharing, the host end
of telnet will use some CPU time. For a couple of users I wouldn't
expect to see an effect. Also, character echo will slow down as the
system gets loaded, since telnetd has to be shceduled twice for each
character. On our Pyramids we put telentd in the kernel, which both
removes the loading effect and removes the echo delay. We have not
tried this on the Sun, but no doubt we will eventually.
The terminal server is a lot more flexible. We are tending to use
that for most new terminals. But it is more complex, and so there
are more things that can go wrong. Where we have a machine whose
users will always be connected to that one machine, we still use
direct terminals. But that is increasingly rare.
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Encore vs. Bridge -- well, actually, I'd also check out cisco - talk
to Len Bosack, President (it's a small company). 415-326-1941. The
only reason we didn't go with cisco was because we didn't think they
could give us much support (they are small and in California). They
have nice boxes. Bridge is cheaper. Cisco and Encore are more
Unix-like. Encore has foreground, background, stopped "jobs", and in
the future will have hooks for implementing your own commands and for
a "security server" running on a BSD Unix system which gets control at
critical times. You can get source for the Annex too, if you want to
do development -- e.g. Univ of Oklahoma is developing some cooperative
processing stuff for "vi" between BSD Unix and the Annex. Oh, I
didn't mention the "leap" code -- Encore has built cooperative
processing into GNUemacs so it talks a special protocol to the Annex
and offloads the host from trivial screen management. I don't use it
personally. There's even a GNU function to show you how many
characters have been saved from host processing through this protocol.
It's not at all clear that the potential bells & whistles on the Annex
save you anything, but the programmers on this Annex say the CS/100
feels quite drab compared to it.
The Annex listens to "rwho" and "routed" packets to learn what to do.
The code to use nameservers is done but they didn't release it yet
because they don't feel like it's industrial strength. The CS/100
etc. have hardcoded routing and macros in them. Which is better?
Depends on who you talk to and how. There are also a bunch of new
options going into the Annex. I don't know what the future of the
Bridge servers is. If you get them with a large number of ports
they're certainly cheaper.
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>Will a terminal server on the ethernet affect paging from the Sun 50's to
>the Sun 160?
Terminal activity is extremely small to begin with, it shouldn't affect
your ethernet traffic. The current release of the Annex software is
geared towards your running the rwho daemon, though. If you don't want
the overhead of the rwho daemon, the only thing you can do is refer to
machines by their internet numbers (this is the route we chose with our
Sun/2's). This changes in their next release scheduled for December (?).
It has some kind of name server builtin.
>2) Besides flexibilty, what do I gain by having my terminals on the
>ethernet? Performance? Would I be better off with an ALM on the VME bus?
Encore has taken a lot of the overhead related to emacs (screen movement, etc)
and let the annex do the work. This results in fewer packets being
propagated over the ethernet => lower overhead for the host computer.
I only know of this working when the host computer is an Encore MultiMax
(which we have), but the propaganda they put out says this works with
any UNIX 4.2 host. It wouldn't be unreasonable to assume they are correct.
Something else you gain is increased baud rate. We run all our staff
terminals (~20) at 19.2 now. It's a noticable difference from 9600 baud.
16 of these terminals are on the same Annex.
The Annex also allows 3 connections for each port. A "simple" job control
facility at the annex level. It may not be readily apparant, but there's
1001 uses for this feature.
I am not immediately familiar with the ALM.
>3) What advantages does the Encore Annex have over the Bridge boxes?
>I would love to hear from anyone who has one.
I am not familiar with the Bridge features, but I can say that Encore is a
UNIX house, and will always be. They would be more likely to cater
to UNIX extras as they came along.
>4) Does anyone have the phone number for Encore? I have the Bridge info.
Chicago Sales Office: +1 312 380-1256
Headquarters Marlborough, MA: +1 617 460-0500
We have been very pleased with our Annexes. They come with 16 serial ports
and 1 parallel port per annex. We had one shipped DOA, but no other problems
hardware-wise. With a University discount, I believe they are somewhere in
the $5-7K range.
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Biases: I am an employee of Encore Computer Corporation; I think the Annex
is cool; an old friend of mine has worked extensively with the Annex. However,
I don't work on the Annex (I'm part of the OS group).
> We have a Sun 160 to which we would like to add about 10 terminals lines.
> The Sun is mainly a file server for 3 3/50's, and the amount of use of
> the terminal ports is expected to be light.
A terminal server may not be strictly cost effective in your environment. Such
a beastie may cost you several hundred dollars per port. An extra serial i/o
card for your Sun, with 16 ports, may be available more cheaply.
> There are other machines on the
> Ethernet that I would like to reach with the terminals, but I could always
> log into the Sun first, and then Telnet or whatever across the ethernet.
> 1) What do I lose by putting my terminals on the ethernet? For example,
> will ^O ^S ^Q all get gobbled rather than passed to Emacs for instance.
> Will a terminal server on the ethernet affect paging from the Sun 50's to
> the Sun 160?
> 2) Besides flexibilty, what do I gain by having my terminals on the
> ethernet? Performance? Would I be better off with an ALM on the VME bus?
There are different performance tradeoffs here. With a serial i/o card, the
Sun probably has to do less work to get a single character; with a terminal
server, the Sun has to process an Ethernet packet. On the other hand, you have
much lower overhead using rlogin or telnet from the terminal server (Annex
support both, don't know about Bridge) directly to another host than doing the
same thing from the Sun. I've spent too much of my life logged into one host
and then rlogin'd/telnet'd to another -- that's several layers of host software
times two host equals painful. For the last several months I've been using a
variety of Annexes to talk to a variety of hosts on the Encore ethernet. The
performance is great -- I can't tell I'm going over the ethernet. I can also
have three simultaneous sessions to different hosts.
The Annex supports RAW, CBREAK, and COOKED modes, so you don't have to send an
entire packet over the net for each character the user types. In the
appropriate mode, character or line i/o is done. I think the Annex can gather
characters from multiple ports destined for the same host and send them in the
same packet. I presume these features may be available on the Bridge as well.
The Annex can be set to pass through ^O ^S ^Q and whatever else you want. I run
gnu-emacs with no trouble, ^S bound to incremental-search, and so on.
Annex traffic doesn't seem to greatly affect or be affected by other network
traffic. I've never noticed a delay. I've also got my Sun NFS'd to a VAX,
sharing the common ethernet. Again, I haven't noticed any problems. However, I
don't do any remote paging (I've only got a single Sun-2 but I'll be getting a
Sun-3 as well in a few weeks).
Terminal servers in general offers more flexibility than serial i/o cards.
> 3) What advantages does the Encore Annex have over the Bridge boxes?
> I would love to hear from anyone who has one.
The Annex also supports a distributed editing protocol known as LEAP. My old
friend who worked with the Annex modified gnu-emacs to support LEAP, which puts
a good chunk of the i/o processing burden in the Annex, where it belongs. The
host doesn't hear from the Annex during editing operations that don't cause
screen refreshes. Encore distributes this version of gnu, and I believe that
the leap modifications are available as part of the standard distribution now,
to boot.
The Annex also supports csh-style job control syntax. Other Annex features,
like inactivity timers, port passwords, and so on may be more or less standard
across terminal servers. One feature I like that may not be unique to the Annex
is the ability to tell the Annex what kind of terminal I have. The Annex will
pass this information along to my login process, in the term variable, so no
matter what machine I login to my termcap information will be set correctly.
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