Cisco 3350 Switch - 30 VLANs with Public IP's ?

[s.nasheet]

Hi ,

I have to configure Cisco 3550 switch L3  that will allow 30 offices all within the same big building to share internet. Each office will have around 5-10 Pc's/Servers. Severs'( Email/Web) need to accessiable from internet. Pc's from one office should not be able to talk to the Pc's in other offices. Each office will have there own router/switch ( for NATing ) which will be connected to Cisco 3550 via Ethernet cable.

10MB Internet will be terminiated on Cisco 3350's fastethernet interface and from there it will be distributed to each office. I have more than 30 public IP address available to support this desing.

I was thinking to create 30 VLANS's ( one for each office ) and assign a public IP to each vlan interface but form that point onward, I can't think how to configure of the network ?

Please see the attached diagram to undestand what I am trying to achieve.

All I need is to provide a ethernet socket to each office with internet connection( one public IP is needed to each office)  where each office will plug there own router/switch for Internet connectivity and LAN.

Can you think of the easites way to configure this network ?

Many thanks for  your advise.

Regards,

[s.nasheet]

Jon ,

Thanks for your all help. I am almost sorted.

I will go for the 2 IP per customer using P2P link bewteen 3350 routed port and customer router. I might need to perform subnetting on public IP block  to configure 3350 interfaces as otherwise I will get ''overlpping IP address'' error.( I think......)

Can I still use 2 IP per customer without subnetting ?

Regards

[Jon Marshall]

s.nasheet wrote:
Jon ,
Thanks for your all help. I am almost sorted.
I will go for the 2 IP per customer using P2P link bewteen 3350 routed port and customer router. I might need to perform subnetting on public IP block  to configure 3350 interfaces as otherwise I will get ''overlpping IP address'' error.( I think......)
Can I still use 2 IP per customer without subnetting ?
Regards

You will have to subnet because you will need separate subnets per customer on the 3550. It would be fine at the customer end but not on the 3550. As you say, you would get overlapping IP address errors on the switch.

Jon

[s.nasheet]

Jon ,

Thanks , All  good, I will create a config  and possibily send you for the review if  you don't mind?

you are the top man.

Regards.

[Jon Marshall]

s.nasheet wrote:
Jon ,
Thanks , All  good, I will create a config  and possibily send you for the review if  you don't mind?
you are the top man.
Regards.

No problem, let me know how you get on.

Jon

[s.nasheet]

Jon,

Its been a long time, Installation didn't go ahead due to some delay by customer, but now they want to get this done.

I have managed to get 128 Public IP address. As  you mentioned before if I had a 2 IP's customer , it will be lot easier. Can you advise how I can assing  2 IP per customer.

Now NATing will be done by Cisco PIX.

Here is what network looks like.

Internet<-----ISP Router<------PIX Firwall<--------Cisco 3350 (One vlan per customer on switch).

Each office/vlan should have its own IP address to go on internet.

I will create a DHCP Pool for each vlan. ( so 30 pools on a switch).

How can we achieve internet connectivity allowing each office/vlan  to have its own public IP address.

Do I need to sub-netting my 128 block address and somehow assign 2 IP per customer ?

Please advise as I am struggling to get this working for ages.

Regards

Salman

[s.nasheet]

Hi,

Just another though.

example

Valn 2 - IP range = 172.16.2.0/24

Vlan interface2

ip address 172.16.2.1 255.255.255.0

ip address 81.50.110.44 255.255.255.255 secondary

And then configfure a VLAN 2 PC's gateway as the 81.50.110.44.

As Vlan interface has  now two IP's Pirmary IP wil use to communicate with Vlan hosts while secondary IP will be used to go on internet. In this case NATing will not be required as firewall will also be the member of same subnet as of 81.50.110.44.

Will this work? Can't test in a lab.

Any thoughts.

Regards

Salman