Re: WAN design

David,

We moved our entire SNA WAN to frame relay this year. We put in a Cisco
2501 router at each site (ordered with the IBM feature set that supports
SNA/APPC traffic). Sprint provides the frame network and offers (as do
several other carriers effective this year) an SNA prioritization
service (it's an extra cost service as you would expect but not a big
difference) that guarantees SNA traffic will be transmitted first over
their network. (It's all encapsulated in TCP/IP.) As far as the routers
are concered, everything is TCP/IP. As far as the AS/400's are concerned
they're talking APPC over an Ethernet line to each other with no
knowledge that there are routers and a TCP/IP frame network in between.
We've never had a line drop due to latency problems. Now, the local
telcos and THEIR propensity to just knock out the service are another
story entirely but the WAN portion in Sprint's control has performed
flawlessly from the first day. We didn't have the human resources to
make an "overnight" switch from one network to another. We ran both
parallel for about a month (we live and die by our network uptime and
senior management would have been livid if the network were down for
even a few hours) so we did have some "gotchas". We had to have two sets
of distribution queues for SNADS since the old queues were pointed to
the old APPC controllers running on the old network and we wanted to
test the new queues on the new APPC setup. (If you don't use SNADS or
Office Vision, this won't apply to you.)

Just be VERY sure you get somebody who knows how to configure the
routers properly for this kind of environment or your network
performance can go to hell in an instant.

You didn't tell us how the current setup is done as far as
bandwidth,etc. so it's hard to say if you need T1 lines or not to the
larger sites. Did you mean fractional T1 so you can exceed 56K per port?
Or full T1? If  you've already got full T1 then you probably need to
keep it. (Frame relay will drop the cost of that quite a bit depending
on the committed information rate you select.) 56K seems to satisfy most
smaller sites quite well. It's a whole lot more bandwidth than we had
before the switch to frame relay at a much lower recurring monthly cost.

We also switched to Ethernet attached laser printers for the LAN (IBM
Network 24's but the HP's will work fine for you, I'm sure) from
3812's/3816's. You lose some features of twinax attached stuff and you
gain some features, too. We don't use IPDS so we didn't lose any print
features by dropping our IPDS capable twinax printers (although the IBM
network printers have IPDS as an option, too). The benefit for us was
printer consolidation and maintenance and other operating cost savings.
Now the AS/400 and PC stuff share the same printers (with much higher
resolution than the 3812/3816 gave us). We have to stock fewer different
kinds of replacement parts (it was in the 1000's $ for 3812/3816 fusers,
developers, etc.) and the monthly maintenance dropped dramatically. And,
of course, they're much faster, too, which made up to the users for
having fewer printers for them to direct their stuff to. The ROI paid
for the new printers.

Now for those really small sites you mentioned. I may have
misinterpreted what you meant by 1 terminal and printer used 15 minutes
every other day so forgive me if I did. I don't have enough info to
fully understand what the situation is and why you wouldn't want to
support a PC (running Client Access or a similar product) for such
casual usage. If the usage is so casual, why have them on a network at
all unless other devices at those locations are sharing it? Perhaps a PC
dialing in to a remote access server (we use Shiva LAN Rovers for that)
would work well at a lower cost. Do you already have something like a
5394/5494 type controller connecting your twinax devices at these small
sites? Are they currently using point to point leased lines? Are there
PC's at these sites that need network access as well? I could point you
in several directions if I knew more.

Randy Mangham
IS Manager
APC, Inc.
San Diego, CA

BORING, David wrote:

> I've got a project coming up where I will have the ability to
> completely
> renovate a client's LAN and WAN. I would like to get some input from
> all
> of you who may be using some of these topologies to see what seems to
> work best with the AS/400.
>
> First off, we will try to go TCP/IP over Ethernet as much as possible,
>
> replacing most green-screen terminals with PC's, but we will probably
> end up with a couple small sites using twinax terminals (1 terminal
> and
> 1 printer that get used 15 minutes every other day is not what we want
>
> to try to support as a PC). My first thought is to put everything onto
>
> frame relay and use some routers to connect all the sites. Most sites,
>
> except the small ones, would probably get connected with a T1 line
> into
> the frame relay network. Could any of you shed some light on your
> WAN's
> and how you have them set up? Especially in regards to the routers
> (I'm
> green on them) and how you handle sending SDLC traffic across the
> frame
> relay network; I've read here about problems some of you have had in
> the
> past with SDLC over frame relay and I'm curious what solved the
> problem.
>
> We are also considering printing options. We currently have
> twinax-connected laser printers and a 6252 printer in place. We are
> thinking of replacing the twinax-connected laser printers with HP
> LaserJet 8000's with a MPI Blue Kit IPDS chip and a JetDirect card. We
>
> are also considering replacing the 6252 with something faster, such as
> a
> 6262. What are you doing for printing to the laser printers? Should I
> use the MPI twinax cards as well or stick with a pure Ethernet
> environment? What are all of you doing for your high speed impact
> printing? Especially in a TCP/IP Ethernet environment.
>
> Sorry for the long post and all the questions, but I would appreciate
> any information anybody could provide. Please feel free to E-mail me
> directly at: dboring@shl.com .
>
> Thanks in advance!
>
> David Boring
> Systems Engineer
> MCI Systemhouse
> Direct: (562) 809-5460
> E-mail: dboring@shl.com
>
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