Need help on 3550 routing/subnetting

[clickaway]

I am looking on subnetting our colo class-C for security and performance reasons, here is our scenario.

One class-C address space, call it
123.123.123.0

subnet mask is
255.255.255.0

our providers gateway router is
123.123.123.1


Connected to our provider, we have a
48-port Cisco 3550 switch running 12.1.22-EA6 (ED) EMI IOS
at 123.123.123.3

All of our hosts are servers and will need to have public IPs from our class-C

We want to divide our network into the following IP address subnets:
One 64 IP address subnet
Four 8 IP address subnets
Four 4 IP address subnets
One 1 IP address subnets (for use with a private 192.168.0.0/24 IP network)

(rest left for expansion)

Im assuming we configure ports on the 3550 as NO SWITCHPORT ports and define them IP addresses of
123.123.123.4
123.123.123.5
123.123.123.6
123.123.123.7
.
.
.

im assuming each of our clients on the individual subnets will then use the corresponding IP as its gateway, but:

-does our provider need to make any changes to the /24 mask they are now giving us?
-how do we set this all up in IOS on the 3550?
-what subnet masks do we give the clients?
-how do we ensure the subnets can talk IP to each if the need to? (routing)
-does any of this involve VLANs?

 

[NetworkGhost]

Not sure what kind of equipment you are supporting but I do have a few questions. Do you have a Firewall in the mix? Do you have a router in the mix? (Beside your ISPs)? Is your ISP router a Router based firewall? If you switch id going to be doing the routing and you want to subnet your network the way you say then you will need to assign one IP from each range to the switch. That will be your gateway IP. The gateway IP has to be in the same subnet as the host devices. If I were you I would seriously consider buying a FW. You can still do your static translations to global IP but you will at least have some protection. A pix 501 should be fine for you depnding on how much traffic you plan on piping through. Why does all of your hosts need global IPs?

 

[MamboDee]

Well to answer your questions in order:

The ISP doesn't need to change the /24 bit mask they gave, however they do need to make sure they assign a mask if /30 bit mask assigned to their router interface. And that they have a route to the rest of your network on their router.

I'll get to setting this up in the IOS in a minute.

Just make sure you give the client the same subnet mask that the vlan has that it's assigned to.

The global config command ip routing needs to be entered before configuration. This will route each vlan that has a ip address assigned.

You use vlans as logical routing interfaces whe configuring layer 3 switching on this particular model of switch.

Here is your config with the subnet layouts <remove comments to paste into switch>:
!
ip routing <enables layer 3 switching aka ip routing>
!
!
vlan 8,16,24,32,48,64,80,96,128 <your access vlans>
!
interface FastEthernet <someting/something> <for connection to your ISP's router>
no switchport
ip address 123.123.123.2 255.255.255.252
!
interface Vlan8
ip address 123.123.123.9 255.255.255.248
!
interface Vlan16
ip address 123.123.123.17 255.255.255.248
!
interface Vlan24
ip address 123.123.123.25 255.255.255.248
!
interface Vlan32
ip address 123.123.123.33 255.255.255.248
!
interface Vlan48
ip address 123.123.123.49 255.255.255.240
!
interface Vlan64
ip address 123.123.123.65 255.255.255.240
!
interface Vlan80
ip address 123.123.123.81 255.255.255.240
!
interface Vlan96
ip address 123.123.123.97 255.255.255.240
!
interface Vlan128
ip address 123.123.123.129 255.255.255.128
!
ip default-gateway 123.123.123.1
!


These commands can be pasted in. I assumed you needed 4/8/64 actual ip address that needed to be assigned to actual computers. I layed out the subnets accordingly. All you need to do is add interfaces into the vlans. You can either hook up a computer or a switch to the ports the further extend the vlans.

VLANs 8,16,24,32 all have 255.255.255.248 subnet mask and can route 6 host max

VLANs 48,64,80,96 all have 255.255.255.248 subnet mask and can route 14 host max

VLAN 128 has a mask of 255.255.255.128 subnet mask and can route 126 host mask

You actually have extra network space:
123.123.123.4 - 7 = 252 = 2 addresses usable (Typically point to point)
123.123.123.40 - 47 = 248 = 6 Ip Address Subnet free for use
123.123.123.112 - 127 = 240 = 14 Ip Address Subnet free for use