Foundry Networks Switch and Router Installation And Configuration Manual page 467

NOTE: This section describes how to change the encapsulation type and MTU for Ethernet ports. To change
these parameters and other packet parameters for POS ports, see "Configuring POS Interfaces" on page 6-5.
Changing the Encapsulation Type
The Layer 3 Switch encapsulates IP packets into Layer 2 packets, to send the IP packets on the network. (A
Layer 2 packet is also called a MAC layer packet or an Ethernet frame.) The source address of a Layer 2 packet
is the MAC address of the Layer 3 Switch interface sending the packet. The destination address can be one of the
following:
• The MAC address of the IP packet's destination. In this case, the destination device is directly connected to
the Layer 3 Switch.
• The MAC address of the next-hop gateway toward the packet's destination.
• An Ethernet broadcast address.
The entire IP packet, including the source and destination address and other control information and the data, is
placed in the data portion of the Layer 2 packet. Typically, an Ethernet network uses one of two different formats
of Layer 2 packet:
• Ethernet II
• Ethernet SNAP (also called IEEE 802.3)
The control portions of these packets differ slightly. All IP devices on an Ethernet network must use the same
format. Foundry Layer 3 Switches use Ethernet II by default. You can change the IP encapsulation to Ethernet
SNAP on individual ports if needed.
NOTE: All devices connected to the Layer 3 Switch port must use the same encapsulation type.
NOTE: POS interfaces use different encapsulation types. See "Changing the Encapsulation Type" on page 6-6.
To change the encapsulation type on a Layer 3 Switch port, use either of the following methods.
USING THE CLI
To change the encapsulation type on interface 1/5 to Ethernet SNAP, enter the following commands:
BigIron(config)# int e 1/5
BigIron(config-if-5)# ip encapsulation ethernet_snap
Syntax: ip encapsulation ethernet_snap | ethernet_ii
USING THE WEB MANAGEMENT INTERFACE
1. Log on to the device using a valid user name and password for read-write access. The System configuration
panel is displayed.
2. Click on the plus sign next to Configure in the tree view to expand the list of configuration options.
3. Click on the plus sign next to IP in the tree view to expand the list of IP option links.
4. Click on the Interface link to display the interface table.
5. Click on the Modify button in the row for the port.
6. Select the encapsulation type from the Encapsulation pulldown menu.
7. Click the Add button to save the change to the device's running-config file.
8. To configure settings for another port, select the port (and slot, if applicable) and go to step 6.
9. Select the Save link at the bottom of the dialog. Select Yes when prompted to save the configuration change
to the startup-config file on the device's flash memory.
December 2000
Configuring IP
15 - 25