3560C Switch terminate on internet modem

[jagan.chowdam]

Hi Guys,

Can some one help with the situation I am facing with Cisco 3560CG Switch.

We have a Cisco WS-C3560CG-8PC-S (Cisco Catalyst 3560-C Switch, 8 GE PoE, 2 dual-purpose uplinks, IP Base image) switch which will be a core switch and the internet link from the ISP is terminated on a Modem.

The ISP configured the internet modem and provided the details such as Gateway IP, Subnet Mask, DNS IP address, Usable IP Address Block,  to configure the switch, where ew have connacted the Modem. When, I verified the details, there were only 4 IP addresses available under Usable IP address block. Spoke with the ISP and they confirmed that they cannot increase the IP Addresses (some limitation on the Modem) in the pool and we have to do NATing at the switching (Which we can't do, because of IP Base image limitation).

About the network, it will be a flat network with only one VLAN which is used for Wireless Guest Access.

Can some help me, how to resolve this issue without buying an additional Router just for NATing?

Please let me know, if you need further details to provide a way to achieve this.

Thanks in advance,

Jagan

[kcnajaf]

Hi Jagan,

Do you have any idea if the Modem support the NAT funtion?.Which Modem are you using? Do you have access the modem?

Other thing which you could do is put a PC there with two NIC card and assign one of the 4 public ip address available to you on one NIC card and perform Internet Connection Sharing (ICS) and connect the second NIC card to the switch. This solution will work for sure but performance wise i'm not much sure :-)

Regards

Najaf

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