Lucent Technologies PortMaster Manual Do Utilizador

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Configuring the Ethernet Interface
4-7
Configuring Ethernet Subinterfaces
Configuring Ethernet Subinterfaces 
With the subinterface feature of the ComOS, you can create up to 512 subinterfaces (the 
total number of interfaces available on a PortMaster) on a single primary Ethernet 
interface. Because you have the bandwidth of only a single Ethernet interface, however, 
efficiency begins to degrade significantly when you add more than 8 subinterfaces.
Subinterfacing is essentially the segmenting of a single wire, or port, into multiple IP 
networks. Instead of subnetting and routing, you can create a subinterface and then set 
it up as you would a standard Ethernet interface. To avoid routing loops, however, you 
must be sure not to create two subinterfaces in the same TCP/IP network on the same 
port. Each Ethernet subinterface must have a unique network.
A drawback to subinterfacing is that it supports static routing only; IPX, RIP, OSPF, 
packet filtering, and route propagation are not supported on subinterfaces.
You must configure the primary Ethernet interface before adding subinterfaces (see 
“Setting General Ethernet Parameters” on page 4-1 for details). After you configure the 
primary Ethernet interface, follow this procedure to add a subinterface.
1.
Create a subinterface.
Command> add subinterface name
This command adds an entry to the subinterface table, which you can then view 
with the show subi command. Remove a subinterface from the subinterface table 
with the del subi command.
2.
Associate the subinterface with a physical port.
Command> set subinterface name port-name portlabel
3.
Assign an IP address or and IP address and net mask to the subinterface.
Command> set subinterface name Ipaddress [/NM]|[Ipaddress/NM]
You can specify the netmask in the /NM or dotted decimal format. You can also 
configure the IP address and netmask separately (see the PortMaster Command Line 
Reference 
for details).
4.
Set the broadcast for the interface.
Command> set subinterface name broadcast high|low