Small office setup - T1 connection, 1 switch, & 1 router and DHCP server config info

[rival9217]

Hey guys and gals - I just wanted to ask (as I literally cannot find the answer to this question anywhere online) what are the names of the cables and ports used to hook up the following (simple) small office network setup that would include a T1 connection, 1 switch, & 1 router:

From the demarc point...what cable and ports are used to hook up the T1 modem to the router, what cable and ports are used to hook up the router to the switch (for both the router and switch).

I'm under the assumption that regular cat 5 goes from the trunk port on the switch to one of the LAN ports on the router but I'm not sure - and I have no idea what cable and ports are used for the T1 modem hookup.

For the DHCP server I would be using in the small office environment: I know how to setup the DHCP helper address on the router so all 3 separate scopes I use for each sub-interface will be routed properly but I have some very basic questions that I technically should know but just honestly don't:

1. after I have everything hooked up....how do I lookup the IP address of the router?

2. when setting up my single DHCP server (with the DNS role installed as well) - do I just select any IP addresses out of the scopes I'm using and set the IP I selected to static (under IPv4 for network settings on the server)? Also, do I select 2 IP's for the DNS entry to set as static as well?

3. Would I need to enter the default gateway address (IP address of the router)on my server config as well?

As always, thanks for any help.

[Reza Sharifi · Accepted solution]

Hi,

From the demarc point...what cable and ports are used to hook up the T1 modem to the router

Usually the providers bring fiber into the demarc and convert it to copper and than copper hand off to the customer (you), which goes directly to your router port (t1). In the old days, you had to have an external CSU/DSU, but all newer t1 modules have build in CSU/DSC and so, you don't need an external one.

I'm under the assumption that regular cat 5 goes from the trunk port on the switch to one of the LAN ports on the router but I'm not sure

You are correct.  You just need a copper cable (Ethernet) between the switch and the router.

1. after I have everything hooked up....how do I lookup the IP address of the router?

Not clear what you are asking, but if you mean how to access the router or the switch, you can access them using the IP address you assign to one of the interfaces or use a  vlan for management.

2. when setting up my single DHCP server (with the DNS role installed as well) - do I just select any IP addresses out of the scopes I'm using and set the IP I selected to static (under IPv4 for network settings on the server)? Also, do I select 2 IP's for the DNS entry to set as static as well?

You would need to reserve a few IPs for the router and the switch and exclude them from the DHCP server. So, if you have for example and IP segment of 192.168.1.0/24 you reserve the first 5 IPs for the router, switch and anything else that may need static IP and the rest will be in the DHCP scope for end devices.

3. Would I need to enter the default gateway address (IP address of the router)on my server config as well?

Yes, every device needs a default gateway to be able to communicate with remote subnets and the Internet.

HTH

[rival9217]

So from what you're saying, is there a simple jack on the wall inside the building that is connected to the demarc point from outside where I would just run a cat 5 cable from it to any one of the 16 T1/E1 ports on the router?

What I mean by the IP address of the router is....when you hook up the T1 modem to your router, the ISP's IP automatically gets added to the routing table - is this now the default gateway IP address to be used on my DHCP server setup or would I also have to NAT it first? Or do I need to set the default gateway/gateway of last resort manually?

Another question I forgot to ask: Should I use an ASA as the router type for this small office setup?

Thanks for your first reply - it definitely helped out.

[Reza Sharifi · Accepted solution]

Correct.  The provider usually gives you a copper hand off from their device in the demarc room. You than run the cable and plug it in to any T1 interface you have.

On your second question, without knowing your design and a diagram it is hard to guess, but once you connect the cable to the router, you need to assign an IP address to it.

question, Is this T1 connecting one location to another or it is used for you to connect to Internet?

If you are simply connecting 2 locations together, you can use any private IP address segment and no need to NAT.  If you are connecting to Internet, than you need to NAT. If you are connecting to Internet, the provider usually gives you some small public IP segment to use for NATing.

As for the firewall, you can use an ASA or you can use other vendors firewalls.  I use Juniper firewalls (see link). They work really well. If you are familiar with Cisco ASA than that would be ok as well.

http://www.juniper.net/us/en/products-services/security/srx-series/srx210/

HTH

[rival9217]

I want users to be able to reach the internet but I don't want any portion of the network on the internet (if that makes sense).

I'm definitely confused now on the IP for the router. After doing the initial config on the router, I was under the assumption that I would just hook it up to the T1 modem, and the IP from the ISP would register in the routing table and I could use that address for the default gateway on my DHCP server. If this is completely incorrect, please advise how I would get the IP.

[Reza Sharifi]

It could be that the T1 interface facing the ISP is using an IP using DHCP.  If that is the case you are correct, you don't need to assign an IP manually to the interface, but most of the time you do manually.  Also, you would need to configure NAT since your users need access to Internet.

HTH

[rival9217]

Ok, so if it is facing the IP, then the gateway address would be given to me by the ISP. If I have to add it manually, then what IP address would I use and what command(s) would I use to add it to the router? And actually, what command would I use to add the IP given by the ISP to add it to the router as well?