Enterasys Networks Network Card manual Before You Begin

Before You Begin Chapter 3

Configuring an ANG-3000/7000

Virtual subnets can use both legitimate IP addresses (unique addresses purchased and registered by your company) and non-routable address ranges reserved for private network use only. These reserved address ranges include:

H10.0.0.0 to 10.255.255.254 on a Class A network

H172.16.0.0 to 172.30.255.254 on a Class B network. Although 172.31.0.0 to 172.31.255.254 is also a reserved range, you cannot define virtual subnets within this range because addresses in that range may be taken by the ANG for internal use.

H192.168.0.0 to 192.168.255.254 on a Class C network

These addresses are not routable outside your corporate network. By using these addresses for remote clients, you can preserve the routable IP addresses for LAN devices.

NOTE

If you allocate addresses from one of these non-routable ranges and you want remote clients to be able to browse the Internet while connected, you must enable the Intelligent Client Routing described on page 31 or use network address translation.

There are several advantages to using virtual subnets over other IP address allocation techniques:

HThe ANG can advertise the virtual subnets before remote clients connect. Using the other techniques, the ANG would only create a host route when the client connected. Because routing protocols may take as long as 30 seconds per router to propagate a host route, the client may remain unreachable for a period of time.

HCreating individual host routes for each remote client as they connect may overload the network’s routers. Because ANG-5000s support 5000 tunnels (ANG-3000s support 500 tunnels), each router may become burdened with 5000 routes in its route table.Virtual subnets can be quickly and easily scaled up to accommodate large number of remote clients. You can modify the subnet mask for an existing virtual subnet to provide additional addresses or create entire new virtual subnets.

28 RiverMaster Administrator’s Guide