Do I need 3 devices ?

I'm a member of a small organization. I'm not a consultant but work for
a computer company. So I guess they figure I know more than they do.
They have asked for my help in a couple of areas.
Networking is not my thing thus Im here asking for some help.

This organization has an ADSL line computing in from the phone company
for there 10-20 computers people use.
The phone company device is a Speed Stream 5360 ADSL Modem.

Someone has connected a line from this device to a Linksys Eitherfast
DSL router Model BEFSR41

Then another line from this device to a 3Com Office Connect Duel Speed
Switch 16 Port. This device of course has network cables running off of
it to all the various computers switches and wireless devices. My
question is do we need the "Linksys DSL Router" Can I simply eliminate
it from the equation. What is it doing there if it should stay? I just
now know if it was put there becsue it is suppose to be there or if its
a left over from a cobbled together network.

Thanks.

On 7 Dec 2006 08:43:28 -0800, steve wrote:

> I'm a member of a small organization. I'm not a consultant but work for
> a computer company. So I guess they figure I know more than they do.
> They have asked for my help in a couple of areas.
> Networking is not my thing thus Im here asking for some help.
>
> This organization has an ADSL line computing in from the phone company
> for there 10-20 computers people use.
> The phone company device is a Speed Stream 5360 ADSL Modem.
>
> Someone has connected a line from this device to a Linksys Eitherfast
> DSL router Model BEFSR41
>
> Then another line from this device to a 3Com Office Connect Duel Speed
> Switch 16 Port. This device of course has network cables running off of
> it to all the various computers switches and wireless devices. My
> question is do we need the "Linksys DSL Router" Can I simply eliminate
> it from the equation. What is it doing there if it should stay? I just
> now know if it was put there becsue it is suppose to be there or if its
> a left over from a cobbled together network.
>
> Thanks.

The router is probably providing NAT and DHCP for your LAN, not to mention
some firewall security. This assumes that the DSL is providing one public
IP Address. If the router was not there, only one of the computers would
connect to the Internet, the others could not. The computers also would not
be on the same LAN subnet without DHCP and NAT.

FedUp wrote:
> On 7 Dec 2006 08:43:28 -0800, steve wrote:
>
> > I'm a member of a small organization. I'm not a consultant but work for
> > a computer company. So I guess they figure I know more than they do.
> > They have asked for my help in a couple of areas.
> > Networking is not my thing thus Im here asking for some help.
> >
> > This organization has an ADSL line computing in from the phone company
> > for there 10-20 computers people use.
> > The phone company device is a Speed Stream 5360 ADSL Modem.
> >
> > Someone has connected a line from this device to a Linksys Eitherfast
> > DSL router Model BEFSR41
> >
> > Then another line from this device to a 3Com Office Connect Duel Speed
> > Switch 16 Port. This device of course has network cables running off of
> > it to all the various computers switches and wireless devices. My
> > question is do we need the "Linksys DSL Router" Can I simply eliminate
> > it from the equation. What is it doing there if it should stay? I just
> > now know if it was put there becsue it is suppose to be there or if its
> > a left over from a cobbled together network.
> >
> > Thanks.
>
> The router is probably providing NAT and DHCP for your LAN, not to mention
> some firewall security. This assumes that the DSL is providing one public
> IP Address. If the router was not there, only one of the computers would
> connect to the Internet, the others could not. The computers also would not
> be on the same LAN subnet without DHCP and NAT.

Thanks for your answer. They have a Windows 2003 server that I think is
doing the DHCP. But certainly all the firewalls you can have can't
hurt. I thought that most of the modems used by phone companies were
already firewalls? Am I wrong? Also just a question to increase my
knowlege here. If they do use a windows 2003 server, couldnt it do what
this middle device does. I'm really just trying to understand it for my
own personal undersanding a bit. Thanks.

On 7 Dec 2006 10:44:40 -0800, "steve" <(E-Mail Removed)> wrote:

>
>FedUp wrote:

>>
>> The router is probably providing NAT and DHCP for your LAN, not to mention
>> some firewall security. This assumes that the DSL is providing one public
>> IP Address. If the router was not there, only one of the computers would
>> connect to the Internet, the others could not. The computers also would not
>> be on the same LAN subnet without DHCP and NAT.
>
>Thanks for your answer. They have a Windows 2003 server that I think is
>doing the DHCP.

It doesn't matter who does DHCP on a simple network. I'm guessing you
are not using WIndows domains, right? In that case DNS is not critical
for the LAN and the DHCP server can be anywhere.

> But certainly all the firewalls you can have can't
>hurt. I thought that most of the modems used by phone companies were
>already firewalls? Am I wrong?

Yes, the modem is only converting DSL to Ethernet, and probably
doesn't do any other processing.

>Also just a question to increase my
>knowlege here. If they do use a windows 2003 server, couldnt it do what
>this middle device does.

Certainly W3K can perform as a router, and provide connection
sharing... But... (big but) that is a more complex configuration that
requires two NICs in the W3K machine (one for the DSL and one for the
LAN) and as well makes all Internet connections dependent on the W3K
machine.

>I'm really just trying to understand it for my
>own personal undersanding a bit. Thanks.

Thanks Peter that helps.

Regards

From: "steve" <(E-Mail Removed)>

| I'm a member of a small organization. I'm not a consultant but work for
| a computer company. So I guess they figure I know more than they do.
| They have asked for my help in a couple of areas.
| Networking is not my thing thus Im here asking for some help.
|
| This organization has an ADSL line computing in from the phone company
| for there 10-20 computers people use.
| The phone company device is a Speed Stream 5360 ADSL Modem.
|
| Someone has connected a line from this device to a Linksys Eitherfast
| DSL router Model BEFSR41
|
| Then another line from this device to a 3Com Office Connect Duel Speed
| Switch 16 Port. This device of course has network cables running off of
| it to all the various computers switches and wireless devices. My
| question is do we need the "Linksys DSL Router" Can I simply eliminate
| it from the equation. What is it doing there if it should stay? I just
| now know if it was put there becsue it is suppose to be there or if its
| a left over from a cobbled together network.
|
| Thanks.

This is as GOOD and correct configuration.

The DSL Modem provides TCP/IP and a WAN IP address.

The Linksys Router allows the one WAN address to be shared by upto 253 TCP/IP nodes.

The The 3Com Ethernet Switch allows 15/16 nodes to connect on the lAN side of the Router.
Depending upon the hardware configuration of the 3Com device, bweteen the 3Com E-Switch and
the posrst on the Linksys Router, you can connect 18 or 19 TCP/IP nodes behind on the LAN
side of the Router all capable of accessing the Internet and providing MS Networking to all
nodes on the LAN side.


Based upon you other replies, I suggest that you tun off DHCP on the Win2003 Server and
allow the Linksys Router to perform DHCP.

I also suggest that on the Linksys Router you specifically block both TCP and UDP ports 135
~ 139 and 445.
--
Dave
http://www.claymania.com/removal-trojan-adware.html
http://www.ik-cs.com/got-a-virus.htm

David H. Lipman wrote:
> From: "steve" <(E-Mail Removed)>
>
> | I'm a member of a small organization. I'm not a consultant but work for
> | a computer company. So I guess they figure I know more than they do.
> | They have asked for my help in a couple of areas.
> | Networking is not my thing thus Im here asking for some help.
> |
> | This organization has an ADSL line computing in from the phone company
> | for there 10-20 computers people use.
> | The phone company device is a Speed Stream 5360 ADSL Modem.
> |
> | Someone has connected a line from this device to a Linksys Eitherfast
> | DSL router Model BEFSR41
> |
> | Then another line from this device to a 3Com Office Connect Duel Speed
> | Switch 16 Port. This device of course has network cables running off of
> | it to all the various computers switches and wireless devices. My
> | question is do we need the "Linksys DSL Router" Can I simply eliminate
> | it from the equation. What is it doing there if it should stay? I just
> | now know if it was put there becsue it is suppose to be there or if its
> | a left over from a cobbled together network.
> |
> | Thanks.
>
> This is as GOOD and correct configuration.
>
> The DSL Modem provides TCP/IP and a WAN IP address.
>
> The Linksys Router allows the one WAN address to be shared by upto 253 TCP/IP nodes.
>
> The The 3Com Ethernet Switch allows 15/16 nodes to connect on the lAN side of the Router.
> Depending upon the hardware configuration of the 3Com device, bweteen the 3Com E-Switch and
> the posrst on the Linksys Router, you can connect 18 or 19 TCP/IP nodes behind on the LAN
> side of the Router all capable of accessing the Internet and providing MS Networking to all
> nodes on the LAN side.
>
>
> Based upon you other replies, I suggest that you tun off DHCP on the Win2003 Server and
> allow the Linksys Router to perform DHCP.
>
> I also suggest that on the Linksys Router you specifically block both TCP and UDP ports 135
> ~ 139 and 445.
> --
> Dave
> http://www.claymania.com/removal-trojan-adware.html
> http://www.ik-cs.com/got-a-virus.htm

Thanks david for your reply. Why do you suggest I block TCP/UDP orts
135-445. What are these ports use for?
Regards

From: "steve" <(E-Mail Removed)>


|
| Thanks david for your reply. Why do you suggest I block TCP/UDP orts
| 135-445. What are these ports use for?
| Regards

That's TCP and UDP Posrt 135 ~ 139 and 445.

These ports are used ny Microsoft Networking. By specifically blocking these posrt you
protect your LAN from hackers and Internet worms from getting in and to keep MS Networking
information from leaking out.

--
Dave
http://www.claymania.com/removal-trojan-adware.html
http://www.ik-cs.com/got-a-virus.htm

David H. Lipman wrote:
> From: "steve" <(E-Mail Removed)>
>
>
> |
> | Thanks david for your reply. Why do you suggest I block TCP/UDP orts
> | 135-445. What are these ports use for?
> | Regards
>
> That's TCP and UDP Posrt 135 ~ 139 and 445.
>
> These ports are used ny Microsoft Networking. By specifically blocking these posrt you
> protect your LAN from hackers and Internet worms from getting in and to keep MS Networking
> information from leaking out.
>
> --
> Dave
> http://www.claymania.com/removal-trojan-adware.html
> http://www.ik-cs.com/got-a-virus.htm
Thank you.