1 network, 2 dsl modems,2 routers

hello all

wanted to find out your opinions on what problems could be caused if a huge network (1 subnet) has 2 dsl modems and the internet is then shared throught 2 routers? the routers are running dhcp

also consider the fact that IP ranges are goin to be set on the routers.

 

Why would you want to setup a network in this fashion?
Did you want to shotgun your DSL connections?

How where you going to set this up?
1 network /w 1 IP range with 2 routers could cause problems. The only way I can possibly see that one work is with a 3 NIC server. Load balance between the 2 NICs connected to the routers and the 3rd NIC will be connected to the network. However this server will get a crazy amount of network traffic, and shouldn't be used for anything else than a proxy and DHCP.

What type of routers are you looking at? SOHO or Enterprise.

Im not sure there is anyother way of setting something like that up without having a common connection point to administer traffic. Atleast not on the networking architechture I learned.

 

ok.

here is the setup: its one company but there are actually 2 buildings on site. Each have been on separate subnets. ONe is goin to be merged with the other.
but there is still the issue of having the 2 modems and routers.. so we were assuming that when the clients send out dhcp requests then either one of the routers will respond and hand out an address. is that possible or chaotic?

 

How many users in each building?

If a hundred or more, I'd leave the two buildings as seperate subnets and connect the two with a layer 3 switch. You will probably get better performance with each subnet having its own DSL connection.

If the total number of users is less than 30, I'd ditch one of the router connections.

In between, two routers is an option. I would set both up with the same settings (for WINS, DNS and such) but each giving out one set of addresses and excluding the addresses of the other. Also gives its own address as the default gateway.

So if you are working in the 192.168.0.0 space you could have:

Router 1 (192.168.0.254)
Gives out IP addresses 192.168.0.1 to 192.168.0.100
Exclusion range 192.168.0.101 to 192.168.0.254
Default gateway 192.168.0.254

Router 2 (192.168.0.253)
Gives out IP addresses 192.168.0.101 to 192.168.0.200
Exclusion ranges (192.168.0.1 to 192.168.0.100) and (192.168.0.201 to 192.168.0.254)
Default gateway 192.168.0.253

That would leave 192.168.0.201 to 192.168.0.252 free for statically assigned resources such as servers.

You then rely on the fact that in most circumstances the nearest router will respond to the BOOTP request first.

You need to make sure that the range of addresses given out by any one of the DHCP servers in this senario is large enough to accommodate all the users (in case one fails). So if you did end up using this set up for a large network with more than 100 users, you should not use the configuration above. In such a case I'd suggest moving to the 10.0.0.0 IP space where there are more options available.

Lastly - don't forget, do not use copper cable to join networks in different buildings. A copper link between buildings can cause a number of safety issues and is never a good idea. Fibre is the best solution, wireless a viable alternative.

 

we presently have an hdsl connection to the other building.

i have always been aware of the fact that the nearest router will respond to the BOOTP request first.. but however we have been getting issues where some of the machines in one building pick up addreses from the router in the other building with the network cable for the hdsl connection is in. so we were wondering how we could get around that

 

The straight forward way is to block the BOOTP requests from going to the other part of the network. Simplest way to do that is block broadcasts (as the initial BOOTP request is a broadcast) by separating the two network into two subnets and connecting them via a layer 3 switch or router.

 

im assuming a SOHO router would not be able to do this ... Thats what i have been provided with

 

You are right - a SOHO router won't have enough ports.

Why is it an issue if PCs pickup DHCP from the router in the other building. If the connection is a reasonable speed between buildings, how much of a problem would it be? How big are your networks? How are you connecting the buildings?

 

It is possible to do this using a soho router but it will depend upon which manufacturer. Please give us a list of the following:

Number of nodes on Lan if possible with the type of node i.e server client printer etc,

BOOTP why is this required ?

The manufacturer and if possible model number of the SOHO routers.

I assume that this is the setup you have so far

Internet <--- Building 1 <----SHDSL---->Building 2 ------> Internet

Is this right or not ?