Mac Addresses - Cisco 7603 - Modular Expansion Base Installation Manual

Port Addresses
Figure 1-41
Port numbers 1/1 to 1/2
Port numbers 2/1 to 2/2
Port numbers 3/1 to 3/4
Port numbers 4/1 to 4/4
Port numbers 7/1 to 7/4
Port numbers 8/1 to 8/8
Port numbers 9/1 to 9/8
Interface ports maintain the same address regardless of whether other modules are installed or removed.
However, when you move a module to a different slot, the first number in the address changes to reflect
the new slot number. For example, on a 4-port OC-12c POS OSM in slot 4 of the Cisco 7609 router, the
address of the top WAN port is 4/1, and the address of the bottom WAN port is 4/4. If you remove the
4-port OC-12c POS OSM from slot 4 and install it in slot 7, the addresses of those same WAN ports
become 7/1 through 7/4.
You can identify module ports by checking the slot and port location on the router. You can also use
software commands to display information about a specific interface, or all interfaces, in the system. To
display information about every interface, enter the show interfaces command without parameters. To
display information about a specific interface, enter the show interfaces type command (type being the
interface type) with the module (slot) number and port number in the format show interfaces type
[mod/port].

MAC Addresses

All network interface connections (ports) require a unique MAC address. The MAC address of an
interface is stored in electrically erasable programmable read-only memory (EEPROM) on a component
that resides directly on the interface circuitry. The router system code reads the EEPROM for each
interface in the system, learns the MAC addresses, and then initializes appropriate hardware and data
structures. Each VLAN in the spanning tree has one unique MAC address. This addressing scheme gives
the router the intelligence to identify the state (connected or not connected) of each interface. When you
hot swap a module, the MAC address changes with the module.
Book Title
1-38
Cisco 7609 Router Port Address Examples
FAN
STATUS
o
INPUT FAN
OUTPUT
OK OK
FAIL
o
INPUT
FAN OUTPUT
OK
OK FAIL
Chapter 1 Product Overview
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