[TriLUG] rfc ISP setup

Aaron S. Joyner aaron at joyner.ws
Sat Nov 25 19:35:05 EST 2006


Jim Ray wrote:

>I'm trying to help an ISP get set up and kindly request comments on the
>procedure.  We have a T1 with a class C block of static IPs and want to
>divide up the static IPs in blocks of 32 and control who gets what.
>
>Since we need 5 blocks, I thought about getting 5 routers and constructing
>the following 5 networks (private IPs substituted for the real IPs, reserved
>range up to 10.10.115.31):
>
>router 1	
>IP allotment	10.10.115.32/27
>network	10.10.115.32
>gateway	10.10.115.33
>server IP	10.10.115.34
>open (usable)	10.10.115.35-62
>broadcast (not usable)	10.10.115.63
>netmask	255.255.255.224
>
>router 2	
>IP allotment	10.10.115.64/27
>network	10.10.115.64
>gateway	10.10.115.65
>server IP	10.10.115.66
>open (usable)	10.10.115.67-94
>broadcast (not usable)	10.10.115.95
>netmask	255.255.255.224
>
>router 3	
>IP allotment	10.10.115.96/27
>network	10.10.115.96
>gateway	10.10.115.97
>server IP	10.10.115.98
>open (usable)	10.10.115.99-126
>broadcast (not usable)	10.10.115.127
>netmask	255.255.255.224
>
>router 4	
>IP allotment	10.10.115.128/27
>network	10.10.115.128
>gateway	10.10.115.129
>server IP	10.10.115.130
>open (usable)	10.10.115.131-158
>broadcast (not usable)	10.10.115.159
>netmask	255.255.255.224
>
>router 5	
>IP allotment	10.10.115.160/27
>network	10.10.115.160
>gateway	10.10.115.161
>server IP	10.10.115.162
>open (usable)	10.10.115.163-190
>broadcast (not usable)	10.10.115.191
>netmask	255.255.255.224
>
>However, the Adtran folks tell me the NetVanta 3205 CSU/DSU coming off the
>T1 has the ability to create zones that will circumvent the use of separate
>routers when used in conjunction with the managed switch and VLANs.
>
>What is the best way to achieve the desired results?
>
>Regards,
>
>Jim
>
>Jim Ray, President
>Neuse River Networks
>tel: 919-838-1672 cell: 919-606-1772
>http://www.Neuse.Net
> 
>Connecting You to the World since 1997
>
>
>  
>
Perhaps I'm not putting it all together quite yet, but I don't quite
understand what you're asking for.  When you say "I'm trying to help an
ISP get set up", are you attempting to help out the ISP folks setup 5
different customers on the other end of a T1 they're selling to
someone?  Or are you trying to help someone who's purchased a T1 and
wants to divide up the /24 (Class C) given to them by their ISP into 5
networks at their location?

Regardless, it's very unlikely that you need 5 routers, in the sense of
5 things with separate power plugs, if they're physically proximal to
each other.  At most, what you might need is a router with 5 or 6
Ethernet interfaces, where 'router' in this sentence could mean a linux
box, a Cisco 2600/2800 series box, or anything similar to those two. 
The least you might get away with would be a fairly smart box with two
Ethernet interfaces (or one Ethernet and one serial, or one Ethernet and
one built in T1 interface, but probably not since you mention a
CSU/DSU), and then a managed switch to break out VLANs from one of the
Ethernet interfaces on the a-fore-mentioned box.

If, on the off chance they're not physically proximal, and you're
talking about 5 remote customers, you're probably in over your head and
should enlist a good network guy.  Even if you got it setup correctly,
you're beyond the point where a passing knowledge will be enough to keep
things stable and happy, and god forbid if you start to put important
services over it and it's stable long enough for you to forget how you
set it up, you'll be trying to find some network guy to help you
troubleshoot at 2am on a Saturday morning when it's all gone south, and
it's not going to be quick to get things going again.  Do yourself a
favor and don't go there.  Just for the record, this may be true of the
first scenario as well.

In short, there's not enough information here.  Please describe in more
detail what you're asking about (ASCII art might be good), and I'll see
if I can make sense out of it.

Aaron S. Joyner




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