Configuration Guide User guide

FastIron Configuration Guide 1189
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Modifying and displaying Layer 3 system parameter limits
If the default route is configured and its next hop ARP is resolved, unknown unicast packets are
hardware-routed to the next hop, and not VLAN-flooded.
Once the device runs out of TCAM, it traps the unknown unicast packets to the CPU for processing.
If the default route is defined and its next hop ARP is resolved, the packets are routed by the CPU.
Otherwise, they follow the default Layer 2 behavior. Because the base Layer 3 code does not allow
route-only configurations, these packets are VLAN-flooded.
The system does not change this CPU-handling behavior back to hardware switching even when
TCAM again becomes available.
FastIron first generation modules
You can configure the following Layer 3 system parameters on FastIron X Series first generation
modules:
• Number of IP next hops and IP route entries
• Number of hardware logical interfaces (physical port and VLAN pairs)
• Number of multicast output interfaces (clients)
These parameters are automatically enabled with pre-defined default values. You can, however,
adjust these values to conform with your network topology.
To display the current settings for the Layer 3 system parameters, use the show default value
command. Refer to “Displaying Layer 3 system parameter limits” on page 1191.
To modify the default settings for the Layer 3 system parameters, use the system max command at
the global CONFIG level of the CLI. Refer to “Modifying Layer 3 system parameter limits on first
generation modules” on page 1189.
Modifying Layer 3 system parameter limits on first generation modules
NOTE
The commands in this section are supported on FastIron X Series devices only.
The Layer 3 system parameter limits share the same hardware memory space and, by default,
consume all of the hardware memory allocated for these Layer 3 limits. Therefore, to increase the
limit for one of the parameters, you must first decrease one or both of the other parameters’ limits.
If you enter a value that exceeds the memory limit, an error message displays and the configuration
will not take effect.
For example, if the network topology has a smaller number of IP next hops and routes, but has
numerous multicast output interfaces, you could decrease the number of IP next hops and routes,
and then increase the number of multicast output interfaces. To do so, enter commands such as
the following.
Brocade(config)#system-max hw-ip-next-hop 1024
Brocade(config)#system-max hw-ip-mcast-mll 2048
Brocade(config)#write memory
Brocade(config)#reload
Likewise, if the network topology does not have a large number of VLANs, and the VLANs
configured on physical ports are not widely distributed, you could decrease the number of
hardware logical interfaces, and then increase the number of IP next hops and multicast output
interfaces. To do so, enter commands such as the following.