What IP to assign to ISP router in packet tracer with /30 subnet?

[ricox]

Sorry if this is in the wrong place.

I'm using packet tracer to create a network for a given company as an assignment. 

I have assigned addressed to build the main network using a /16 subnet but am unsure of how to implement connection to the router which I've been asked to use the /30 subnet for. 

If my ip address from the non isp router is 10.65.0.1 then what would the address for the ISP router be over the serial connection?

[Jon Marshall]

10.65.0.2 255.255.255.252

Jon

[Joseph W. Doherty]

Just to add to Jon's information.

An IP of 10.65.0.1, using a /30 would map out as:

10.65.0.0 network address
10.65.0.1 host address
10.65.0.2 host address
10.65.0.3 broadcast address

As you also mention you're to use a /16 as the main network (BTW, that's a very large network, i.e. unlikely to ever see such in the "real world"), the 10.65.0.0/30 would preclude using 10.65.0.0/16 as a network.  (NB: you could use 10.65.0.0/16 as an address block, i.e. you can allocate multiple networks from it, any smaller than the /16.)

[ricox]

I wouldn't use this IP address myself but It's what I've been told to work with for whatever reason.

I started working on this a few weeks back and unfortunately have forgotten most of what I've done to this point haha. 

The network I actually have to setup should be attached. 

The IP address 10.65.0.1 serves the interface to the left of the router to the left. Devices connected under this router use 10.65.64.X

Am I right in assuming I can assign the ISP as 10.65.0.2 (perhaps I should switch them around?).

[Jon Marshall]

Not sure what swapping the IPs around would do. 

Also it is not clear which interface on the router on the left you are assigning the IP to but it has to be the interface connecting to the ISP router. 

Jon

[Joseph W. Doherty]

"Am I right in assuming I can assign the ISP as 10.65.0.2 (perhaps I should switch them around?)."

In the "real world", the ISP would tell you what IP they are using and what your network allocation is.  For using 10.65.0.0/30 it doesn't matter which side using .1 vs. .2, although I've seen conventions such as the lower IP is on the "inner/core" facing side and the higher IP on the "outer/edge" facing side.  Again, though, technically, it doesn't matter.

"Devices connected under this router use 10.65.64.X"

You didn't note the network size, although I believe you imply a /24.  If so, i.e. a /24, that doesn't overlap with your /30, but larger network address blocks could.  (BTW, also keep in mind, under classful rules, 10.x.x.x is a /8.  [Which can cause problems if using a classful routing protocol like RIPv1.])