Configuring IP
December 2005 © Foundry Networks, Inc. 16 - 29
NOTE: The basic procedure for changing the static ARP table size is the same as the procedure for changing
other configurable cache or table sizes. See the section “Displaying and Modifying System Parameter Default
Settings” on page 4-8.
To increase the maximum number of entries in the static ARP table you can configure on a Foundry Layer 3
Switch, enter commands such as the following at the global CONFIG level of the CLI:
FESX424 Router(config)# system-max ip-static-arp 1000
FESX424 Router(config)# write memory
FESX424 Router(config)# end
FESX424 Router# reload
Syntax: system-max ip-static-arp <num>
The <num> parameter indicates the maximum number of static ARP entries and can be a number in one of the
following ranges, depending on the device you are configuring. The table below lists the default maximum and
range of configurable maximums for static ARP table entries supported on a Foundry Layer 3 Switch.
Configuring Forwarding Parameters
The following configurable parameters control the forwarding behavior of Foundry Layer 3 Switches:
• Time-To-Live (TTL) threshold
• Forwarding of directed broadcasts
• Forwarding of source-routed packets
• Ones-based and zero-based broadcasts
All these parameters are global and thus affect all IP interfaces configured on the Layer 3 Switch.
To configure these parameters, use the procedures in the following sections.
Changing the TTL Threshold
The TTL threshold prevents routing loops by specifying the maximum number of router hops an IP packet
originated by the Layer 3 Switch can travel through. Each device capable of forwarding IP that receives the packet
decrements (decreases) the packet’s TTL by one. If a device receives a packet with a TTL of 1 and reduces the
TTL to zero, the device drops the packet.
The default TTL is 64. You can change the TTL to a value from 1– 255.
To modify the TTL threshold to 25, enter the following commands:
FESX424 Router(config)# ip ttl 25
Syntax: ip ttl <1-255>
Enabling Forwarding of Directed Broadcasts
A directed broadcast is an IP broadcast to all devices within a single directly-attached network or sub-net. A net-
directed broadcast goes to all devices on a given network. A sub-net-directed broadcast goes to all devices within
a given sub-net.
Table 16.6: Static ARP Entry Support
Default
Maximum
Configurable
Minimum
Configurable
Maximum
512 512 1024
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