Configuring IP
December 2000 15 - 5
IP Address MAC Address Type Age Port
1 207.95.6.102 0800.5afc.ea21 Dynamic 0 6
Each entry contains the destination device’s IP address and MAC address.
Static ARP Table
In addition to the ARP cache, Layer 3 Switches have a static ARP table. Entries in the static ARP table are user-
configured. You can add entries to the static ARP table regardless of whether the device the entry is for is
connected to the Layer 3 Switch.
NOTE: The Layer 3 Switches have a static ARP table but Layer 2 Switches do not.
The software places an entry from the static ARP table into the ARP cache when the entry’s interface comes up.
Here is an example of a static ARP entry:
Index IP Address MAC Address Port
1 207.95.6.111 0800.093b.d210 1/1
Each entry lists the information you specified when you created the entry.
To display ARP entries, see the following:
•“Displaying the ARP Cache” on page 15-89 – Layer 3 Switch
•“Displaying the Static ARP Table” on page 15-91 – Layer 3 Switch only
•“Displaying ARP Entries” on page 15-105 – Layer 2 Switch
To configure other ARP parameters, see the following:
•“Configuring ARP Parameters” on page 15-29 – Layer 3 Switch only
To increase the size of the ARP cache and static ARP table, see the following:
• For dynamic entries, see “Displaying and Modifying System Parameter Default Settings” on page 10-70 –
Layer 2 Switches and Layer 3 Switches. The ip-arp parameter controls the ARP cache size.
• Static entries, “Changing the Maximum Number of Entries the Static ARP Table Can Hold” on page 15-33 –
Layer 3 Switches only. The ip-static-arp parameter controls the static ARP table size.
IP Route Table
The IP route table contains paths to IP destinations.
NOTE: Layer 2 Switches do not have an IP route table. A Layer 2 Switch sends all packets addressed to
another sub-net to the default gateway, which you specify when you configure the basic IP information on the
Layer 2 Switch.
The IP route table can receive the paths from the following sources:
• A directly-connected destination, which means there are no router hops to the destination
• A static IP route, which is a user-configured route
• A route learned through RIP
• A route learned through OSPF
• A route learned through BGP4
The IP route table contains the best path to a destination.
• When the software receives paths from more than one of the sources listed above, the software compares
the administrative distance of each path and selects the path with the lowest administrative distance. The
administrative distance is a protocol-independent value from 1 – 255.
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