Sunday, October 30, 2005

Hardware Review 1: Zyxel Prestige 660R DSL Modem

Zyxel DSL Modem has a quite a good form, which can be a factor in marketing appearance. Its blue and sturdy look provides a feeling of reliability and high performance to clients connected to DSL services. It has the same basic stuff inside (NAT,Port Forwarding, SPI, Access List, Routing, Bridge, etc). However i was interested on one feature which is the IP Alias. IP Alias is the capability of one modem to share 1 public IP to 3 different network. Which means, that i can connect 3 VLAN's or different LAN to internet access and denied others without the need to put in a router or a layer 3 switch. For example, I have 3 VLAN's for each department which is Engineering, IT and Customer Service. The reason for the VLAN is to separate each department' network, to improve security and access to dedicated servers. However, i need to connect Engineering and IT to Internet but still maintain their VLAN ID. With IP alias, we can just easily connect the two VLAN without the need to change their IP or disable their VLAN assignment. It's a simple feature but helpful, especially when IT budget is limited.

Other feature also is the address to address mapping. Which means you can map several public IP to different Private IP. For example, you have 3 servers in the data center. A VoIP server, Application server and a File Server. You need to separate each access, so you assign each with public IP. However, your concern with security, so you need to assigned it with a Private IP, while doing NAT to mask your LAN IP's. Others may opt to do routing, but with this modem, you can keep the NAT and still come up with the same objective.

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