The following example shows the priority of ingress ARP packets set to level 7.
Brocade(config)# arp-internal-priority 7
Conguring forwarding parameters
The following congurable parameters control the forwarding behavior of Brocade 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 aect all IP interfaces congured on the Layer 3 switch.
Changing the TTL threshold
The time to live (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 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 value for the TTL threshold is 64. You can change the TTL threshold to a value from 1 through 255.
To modify the TTL threshold to 25, enter the ip ttl command.
device(config)# ip ttl 25
Syntax: ip ttl ttl-threshold
Enabling forwarding of directed broadcasts
A directed broadcast is an IP broadcast to all devices within a single directly-attached network or subnet. A net-directed broadcast goes
to all devices on a given network. A subnet-directed broadcast goes to all devices within a given subnet.
NOTE
A less common type, the all-subnets broadcast, goes to all directly-attached subnets. Forwarding for this broadcast type also is
supported, but most networks use IP multicasting instead of all-subnet broadcasting.
Forwarding for all types of IP directed broadcasts is disabled by default. You can enable forwarding for all types if needed. You cannot
enable forwarding for specic broadcast types.
To enable forwarding of IP directed broadcasts, enter the ip directed-broadcast command in device conguration mode.
device # configure terminal
device(config)# ip directed-broadcast
Syntax: [no] ip directed-broadcast
Brocade software makes the forwarding decision based on the router's knowledge of the destination network
prex. Routers cannot
determine that a message is unicast or directed broadcast apart from the destination network prex. The decision to forward or not
forward the message is by denition only possible in the last hop router.
To disable the directed broadcasts, enter the no ip directed-broadcast command in device conguration mode.
device # configure terminal
device(config)# no ip directed-broadcast
Conguring IP parameters - Layer 3 switches
FastIron Ethernet Switch Layer 3 Routing
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