VLSM

[tazlady63]

I am trying to figure out how to setup a VLSM with four routers, one is the main one leading to the internet Class C network and then the other 3, one with 50 nodes, one with 20 and the other with 28 nodes. I know VLSM is the best setup for this, I understand basically the IP range for the routers just not what to set the Main routers S0, S1, S2 and S3 then the others S0 and E0. Using 2600. I already know that this should be right the node with 50 the IP would be something like 192.175.5.0/26, 28 nodes 192.175.5.64/27 and 20 nodes as 192.175.5.96/27

[james4627]

Here is what your nets could look like:

192.168.1.0/26 (for 50 nodes)

192.168.1.64/27 (for 20 nodes)

192.168.1.96/27 (for 28 nodes)

Serial point-to-point nets to main:

192.168.1.128/32

192.168.1.132/32

192.168.1.136/32

192.168.1.140/32

Hope this helps.

[tazlady63]

Okay so that is my S0, S1, S2 and S3 settings then for the main router, what is the S0 and E0 for the other three then. S0 to match the main router then the E0 as the broadcast IP for that range such as for Router with 50 nodes the E0 at 192.168.1.63

[james4627]

Well, those are the nets... The IPs of the interfaces you will have to define. For example:

Main to R1 serial:

Main .129, R1 .130

Main to R2 serial:

Main .133, R2 .134

Main to R3 serial:

Main .137, R3 .138

The Ethernet interfaces on the "spokes" could be:

R1 (50 nodes): 192.168.1.1 (63 broadcast)

R2 (28 nodes): 192.168.1.65 (95 broadcast)

R3 (20 nodes): 192.168.1.97 (127 broadcast)

[tazlady63]

So is this what I am looking at or am I wrong and should have set them all at in the interal IP of 192.168.1.X

Router Main Interface IP address

S0 192.175.5.0

S1 192.175.5.129

S2 192.175.5.135

S3 192.175.5.137

Router Router 20 nodes S0 192.175.5.134

E0 192.175.5.65

Router Router 50 nodes S0 192.175.5.130

E0 192.175.5.1

Router Router 28 nodes E0 192.175.5.97

S0 192.175.5.138

Subnet IP address range

Subnet Router 50 nodes192.175.5.0/26 192.175.5.1 -192.175.5.62

Subnet Router 20 nodes192.175.5.96/27 192.175.5.97- 192.175.5.126

Subnet Router 28 nodes 192.175.5.64/27 192.175.5.65- 192.175.5.95

[james4627]

I am not sure I understand the question. You will be connecting three routers to the hub router via serial, right? And these three spokes will have the end-device networks behind them, right? So, the hub will connect the spokes via S1,2, and 3. S0 will connect somewhere else or be unused... If it connects somewhere else, you will need a different net... And remember, the interfaces on the router are allocated a valid IP in the network "range." You put .0 for S0. That is a network address, not IP address (for your class C at least).

If you think of it as a tree, the hub router will have three branches, and these branches will have the /32 networks connecting them to the hub, or trunk if you will... Then the branches will have the leaves (hosts) connected to each of the branches by the /26 and two /27 nets...

And make sure you get the IPs in the small nets correct. As you posted them, they are off...

[tazlady63]

Okay then I suspect I thought I understood, I am trying to figure out the actually break down for the IP for a Class C with the IP given to them such as 192.175.5.0 this is the Internet Assigned Number then using VLSM make a design to broadcast under that one network. I have attached a basic diagram.

[tazlady63]

attachment now

[james4627]

Ok... So my second post will fit this topology perfectly:

Main to R1 serial:

Main .129, R1 .130

Main to R2 serial:

Main .133, R2 .134

Main to R3 serial:

Main .137, R3 .138

The Ethernet interfaces on the "spokes" could be:

R1 (50 nodes): 192.175.1.1 (63 broadcast)

R2 (28 nodes): 192.175.1.65 (95 broadcast)

R3 (20 nodes): 192.175.1.97 (127 broadcast)

Voila.

[tazlady63]

Thanks alot..