Google Answers Logo
View Question
Q: T1 - CSU/DSU - Channel Bank - Router ( Answered,   2 Comments )
Subject: T1 - CSU/DSU - Channel Bank - Router
Category: Computers > Hardware
Asked by: billhamler-ga
List Price: $50.00
Posted: 16 May 2002 07:51 PDT
Expires: 23 May 2002 07:51 PDT
Question ID: 16571
We are opening a branch office and will be connecting the 2 facilities
with a Point to Point T1.  We will operate a NetWare 5.1 server at our
main location with 10 Windows 2000 workstations.  At our branch we
will have 3 Windows 2000 workstations.

We of course need to connect the T1 to our network in such a way that
all workstations at each end are part of the network.  In addition we
want to connect our (new - to be purchased) telephone equipment to the
T1 so that 2-3 channels are used for inter-office voice and for
transferring calls between offices.

I am having difficulty in understanding the relationship and our need
for each of the following types of equipment:

Channel Bank
Digital Modem
Network Hub

We also have a DSL line for our internet access.

We have quotes from three (3) Local Service Providers for the T1.  2
of them provide the T1 simply terminated with an RJ-45 jack.  The 3rd
includes a channel bank on each end with a "v.35 handoff".

I have the need to speak with someone who can provide me with
understandable definitions of the above equipment, what we need and
what we don't need.
Subject: Re: T1 - CSU/DSU - Channel Bank - Router
Answered By: answerguru-ga on 16 May 2002 09:17 PDT
Hi there,

I can definitely help you with this situation...lets start with the
definitions of the specified equipment:

1. Channel Bank 
Here is the definition:
Here is the definition:

3. Digital Modem 
Here is a definition:

4. Router
Here is a concise view of the advantages/disadvantages of having a

Higher throughput than most software + computer solutions (especially
Windows based)
Doesn't require a computer to be running to allow access for other
Reliable and runs without much, if any attention, once you set it up.
Doesn't contain any files or software that can be harmed, stolen,
copied, deleted, etc.


Higher cost than using part of an existing computer. 
Still requires configuration. 
May not support VPN or tunneling at all, or may have only limited
May not support the applications that you use.

Here is a definition of what a router is and does:
"Routers isolate each LAN into a separate subnet, so each network
adapter's IP address will have a different third "octet" (Example: and are in different subnets.).  They are
necessary in large networks because the TCP/IP addressing scheme
allows only 254 addresses per (Class C) network segment.

Routers, like bridges, provide bandwidth control by keeping data out
of subnets where it doesn't belong.   However, routers need to be set
up before they can get going, although once set up, they can
communicate with other routers and learn the way to parts of a network
that are added after a router is initially configured.

Routers are also the only...devices that will allow you to share a
single IP address among multiple network clients."
5. Network Hub 

Here is a definition of a hub:
"A hub takes the data that comes into a port and sends it out all the
other ports in the hub.  It doesn't perform any filtering or
redirection of data. Although it's actually a little more complicated,
you can think of a hub like a piece of wire.  A better analogy might
be that of an Internet Chat room.  Everything that everyone who joins
a particular chat is seen by everyone else.  If there are too many
people trying to chat, things get bogged down."

From what you have mentioned regarding the NetWare server, P2P T1, and
Windows 2000 workstations you should have no problems.
If you refer to the definition for a channel bank, you will see that
such a device is needed for high-volume digital transmission
applications. Since I don't know the nature of your company's
operations that's all I can provide about that at this point.

You may find this message thread interesting...they are talking about
a card that is able to bypass the "v.35 handoff" and connect directly
into the would have to weigh the differential costs of
your third quote with the cost of implementing this card installation.
Remember that this option will not have a channel bank (which may or
may not be relevant for you).

Your P2P T1 connection will serve to connect all of your workstations
in both locations (use the NetWare software to set privileges within
the network). As for the 2-3 voice lines..the implementation of this
is dependant upon the equipment provided. Just worth mentioning also
that for voice communication, the channel banks would improve the
sound quality of calls (if regular phone lines are not clear enough
for you).


If you need any help with the information provided here I would be
happy to help..just post a clarification :)

Good luck in your networking endeavours!


Request for Answer Clarification by billhamler-ga on 17 May 2002 06:12 PDT
Thanks for your answer. It has clarified some of the issues for me
however, I do need some additional information.  As I review (again)
the information provided by the (3) Local Service Providers who are
bidding on our business and the four (4) telephone equipment
providers, where my confusion seems to be is in exactly what equipment
is necessary.

Do I need a Channel Bank, CSU/DSU and a Router (in addition to the hub
that we now use for our Windows network) to interface the T1 with our

Perhaps I should expand on our situation.

Right now we have a Windows98 peer-to-peer network that uses an
inexpensive 16 port Linksys Hub.  We also have DSL from our local
telco.  I connect the DSL modem to a 4port Netgear Router and I
connect the Router to the Linksys Hub.  And of course each of the 4
PCs connect to the Linksys Hub.

When we upgrade to a NetWare server based system, we will attach the
server and additional PCs to the Linksys Hub (although our software
vendor has suggested we consider replacing the Hub with a Router for
more efficient throughput).

One of the telephone equipment vendors is quoting an Avaya Superpipe
155 (another is quoting an Adtran) router which the salesperson claims
will take a v.35 handoff from the telco's channel bank and provide
10/100 output to our Linksys Router.

Another vendor is indicating that they will terminate the T1 at an
RJ-45 jack and that we will need to purchase something such as a Cisco
1720 Router with an installed CISCO WIC-1DSU-T1 card.

To add more confusion, it seems to me that the vendors use different
terminology for similar items.  That is the reason for my original
question regarding what each item is.

Getting back to the practical question of what do we need to "attach"
the T1 to our network.

Do we need a channel bank?
Do we need a CSU/DSU?
Do we need a CISCO 1720 type router with a WIC card?
Do we need anything else?
Are any of the above just different terms for the same equipment.

Clarification of Answer by answerguru-ga on 17 May 2002 09:41 PDT
Hi again,

You will require a CSU/DSU and a router. This will provide more
efficient throughput as your software vendor mentioned. The CSU/DSU is
simply required for any T1 or T3 connection.
The channel bank, as I mentioned before, is a good piece of hardware
to have since you want those 2-3 voice lines..with the channel bank
you can simply plug these in. I would suggest a cost/benefit analysis
from someone who can view your site in person.
Let me make this simple for you:

1. If you have a channel bank:
You do NOT need the WIC cards
The CISCO 1720 will still work but now you have a wider choice of
routers (such as the Avaya)

2. If you don't have a channel bank:
You DO need both the WIC cards AND the CISCO 1720 router
As far as getting the T1 onto the network, you will be connecting the
network through the two channel banks (if you choose that option) or
through two routers at either end of the network.

Hope that clears everything up :)

Request for Answer Clarification by billhamler-ga on 17 May 2002 14:26 PDT
I'm getting there. :) :) I've been working with PCs and some networks
since 1980, however over the past 4-5 years I've come to realize that
I'm becoming more and more technologically challenged. Here is what I
think I understand so far --->

The channel bank interfaces with our network hub via the Avaya
Superpipe (or a Cisco 1720 with no WIC card).

The Avaya Superpipe (or Cisco 1720) connects to our existing Linksys
Hub (or another router if we choose to "upgrade").

Where does the CSU/DSU fit in?

Clarification of Answer by answerguru-ga on 17 May 2002 18:40 PDT
Hi Bill,

The CSU/DSU is required in both situations to sustain your t1 connection.


Request for Answer Clarification by billhamler-ga on 19 May 2002 07:08 PDT
If the T1 connects to a channel bank, and the channel bank connects to
the Avaya router and the Avaya router connects to our network hub,
where does the CSU/DSU fit in?

Clarification of Answer by answerguru-ga on 19 May 2002 09:39 PDT
Hi Bill,

I've been looking high and low for a network diagram that shows where
the CSU/DSU fits in but to no avail...I am sure that you do need it in
either configuration from previously researched material. I believe it
has the following configuration, but you should ask the companies
providing you with quotes for more information on this:

(channel bank A)--(CSU/DSU)-----------T1----------(CSU/DSU)-----(channel
bank B)

It's been a pleasure helping you...good luck in your network upgrade

Subject: Re: T1 - CSU/DSU - Channel Bank - Router
From: brad-ga on 16 May 2002 08:09 PDT
Good Day,BillHamler-ga.

My techie buddy, Bobby Chapman, has been in the telecommunications
field for a century or two.  Bobby said you can email him and he will
clarify all this for you.  Email Bobby at  A busy
guy, but Bobby loves his telecom career and has all the answers from
years of experience and education.

Subject: Re: T1 - CSU/DSU - Channel Bank - Router
From: chrismbg-ga on 16 May 2002 16:27 PDT
Just some quick information for you -

- Depending upon pricing, of course, ideally you would want to choose
the company offering the channel banks. The channel banks will
seperate the T1 into channels (as the name suggests). 2 - 3 of those
channels can be used for voice. They will plug into your PBX (new
phone equipment). The "v.35" handoff will connect to your router. This
allows the router to communicate over the T1. Both ends will be
configured in the same manner.

- You will need a router at either end of the circuit (T1) to allow
for data communications. I suggest a Cisco 1700 or 1800 series router
as they are inexpensive, reliable, and support the V.35 handoff. You
will need to configure both IP and IPX routing on the routers unless
your Netware server runs only IP. Netware 5.1 is capable of running IP
only and I suggest using it in that manner since IP would be your only
needed protocol at that point.

- The "digital modem" is nothing but a modem for your DSL connection.
I suggest that you purchase a Linksys or Netgear DSL Router/Firewall
for your Internet connection. This will provide a layer of security.
Make sure you check with your ISP and see if the DSL requires PPPoE.
If so, you need to make sure that your DSL router/firewall supports
PPPoE. PPPoE allows for authentication over Ethernet - it's kind of
like simulating dial up with a network connection.

- The hubs are necessary for your network. The hub allows all network
devices (routers, DSL routers, PCs, and server) to communicate with
each other. A switch is a similar device but provides better
performance and manageability. I would strongly suggest purchasing a
switch over a hub. They both will do the same thing but the switch
will do it better.

I recommend Cisco for routers and switches and Linksys or Netgear for
the DSL firewall. You'll get the best bang for your buck. I also
suggest hiring someone to install the equipment and confirm that
everything works. If you have no experience with this type of
configuration, there is a lot of room for error and headache!

Important Disclaimer: Answers and comments provided on Google Answers are general information, and are not intended to substitute for informed professional medical, psychiatric, psychological, tax, legal, investment, accounting, or other professional advice. Google does not endorse, and expressly disclaims liability for any product, manufacturer, distributor, service or service provider mentioned or any opinion expressed in answers or comments. Please read carefully the Google Answers Terms of Service.

If you feel that you have found inappropriate content, please let us know by emailing us at with the question ID listed above. Thank you.
Search Google Answers for
Google Answers  

Google Home - Answers FAQ - Terms of Service - Privacy Policy