TELECOM 247

I have just inherited four sites linked via BT Kilostream circuits.

Theres some old Cray DCX 818 and BT multiplexers connected to the
Kilostream NTEs and the end result is that the remote sites have async
terminal access to a central computer system.

Although everything works OK, the muxes are temperamental - they are
maintained by BT but are often in need of attention.

Not having worked with such circuits for many years, I would like to
open up the following questions to the floor...

What modern kit could replace the muxes?

What are the pros and cons of replacing the Kilostream circuits with
broadband? I would expect Kilostream to actually be more reliable but
obviously slower.

Can you get an ADSL async stat mux?

Thanks

NK

Nigel Kendrick wrote:


ADSL will be less predictable than kilostream, contention may not be a
frequent issue yet, but it could be, also with most providers you only
get 256Kbps upload regardless of what download speed you get, also ADSL
tends to be liable to far more interruptions for
upgrades/problems/loadbalancing anywhere from BT to your ISP

Nigel Kendrick wrote:

I suspect most people would consider upgrading the terminal
equipment at the same time. If the computer can run telnet,
it could be accessed from any networked PC, though youd
have to watch out for compatible terminal emulations and
protocol support. If not, there are Terminal Servers that
can provide async access via IP networks. They can be used
end-to-end like the stat-muxes. Some can provide remote
telnet access to a central bank of async ports. Costs are
from around Ł100 per port.

Security via the Internet would be more complicated. That
could be addressed with a firewall/VPN set-up, not
necessarily cheap for a professional solution, but youd be
looking at something that would be compatible with a
long-term networking strategy so you wouldnt be left with
even more legacy equipment when the applications eventually
migrate to a modern platform.

An intermediate solution would be to bridge/route the LANs
via the Kilostream circuits, using TS hardware described
above, then migrating to DSL later. If the applications are
stuck with low-speed terminals, this might give adequate
performance and the network would stay private.

On Wed, 21 Dec 2005 00:54:51 +0000, Jim wrote:


ADSL circuits to interconnect the sites without using the internet are
also possible.

Phil
--

Usenet spam eaten by a Hamster http://www.tglsoft.de/
No more cable clowns :-))
Please do not feed or re-quote the trolls.

In article , Phil Thompson
writes

Could you not replace the other equipment with ordinary PCs and use the
central one as a file server and run that over a VPN on Broadband?.

Weve done this a few times, and very well its worked too:!....
--
Tony Sayer

Nigel Kendrick wrote in
message news:43a8829d$0$29560$da0feed9@news.zen.co.uk...

i have done this before with cisco routers.

you can put async modules in the router which make it act like a terminal
server.

the router could drive your existing kilostream link, or an ADSL or other
type of WAN - once you get to 1841 or 2800 routers the WAN interfaces are
modular.

1 thing to remember is that any routed link is not going to be as bandwidth
efficient as the stat mux - all that TCP/IP overhead adds up.

A lot of old kilostream corporate networks have migrated to ADSL. However,
conventional circuits have been getting cheaper for years, so new point to
point links may work out reasonable, even with higher bandwidths.

you can go for a Internet based service (in which case you need encryption
and router security to keep your network walled off from the Internet).
or you could use a private ADSL / IP service (popular with a lot of retail
chains) - most of these seem to be based on an MPLS core. however although
there are a lot of providers, you may find the overhead costs painful with
only 4 sites.

use a modular router and build it the way you need.

i suggest you split this into 2 separate issues
1. what is the end user devices - if they are PCs then you may not need
terminal servers at all
2. what should the transport be (almost certainly IP?) - but then you need
to decide on the underlying WAN.

the other thing is to step back from your current issue and plan what you
want so that it will last for a while, and whether other changes you expect
mean alterations to the WAN in the next few years.

for example, if you still have terminals, there might already be plans to
swap them out for PCs / Citrix terminals. If so your new IP network could
support old kit, new, or both (with enough bandwidth ) depending on the
timescales.
--
Regards

stephen hope@xyzworld.com - replace xyz with ntl

Nigel Kendrick wrote:

Others have mentioned alternative kit and ADSL pros/cons, but have you
considered asking BT what other solutions they have to offer? Chances
are they wont want to lose your business - so find out what they have
to offer then negotiate the price down. If any of your sites are in
areas covered by cable companies, they may also be able to offer
solutions.

At the end of the day, it all depends on how much time you want to
invest in the investigation/negotiation process plus the cost of the
final solution vs the quality of service (contracted % uptime, response
time to problems, etc.).

Bob

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Nigel Kendrick wrote:

The biggest con is that there is no SLA for ADSL, your links could go
down not for hours or days but in an extreme case it could be weeks or
months. All other problems to do with changing from Kilostream to ADSL
can be worked around except for that one point.

So you have to ask yourself how important is it for the links to be
there 24/7 & how could it work if a link goes down for X number of days.

I have also experienced problems caused by remote routers on links
locking up the connections, not to sure whether you have to same with
Kilostream or not, but it is another con...

As I said it will all depend on whether you can live with a SLA or not,
private wires. aka kilostream are always treated with high importance,
not so DSL.