Configuration Guide User guide

FastIron Configuration Guide 1043
53-1002494-02
IPv4 point-to-point GRE tunnels
NOTE
When DHCP Assist is enabled on any port, Layer 2 broadcast packets are forwarded by the CPU.
Unknown unicast and multicast packets are still forwarded in hardware, although selective packets
such as IGMP are sent to the CPU for analysis. When DHCP Assist is not enabled, Layer 2 broadcast
packets are forwarded in hardware.
Configuring DHCP Assist
You can associate a gateway list with a port. You must configure a gateway list when DHCP Assist is
enabled on a Brocade Layer 2 Switch. The gateway list contains a gateway address for each subnet
that will be requesting addresses from a DHCP server. The list allows the stamping process to
occur. Each gateway address defined on the Layer 2 Switch corresponds to an IP address of the
Brocade router interface or other router involved.
Up to eight addresses can be defined for each gateway list in support of ports that are
multi-homed. When multiple IP addresses are configured for a gateway list, the Layer 2 Switch
inserts the addresses into the discovery packet in a round robin fashion.
Up to 32 gateway lists can be defined for each Layer 2 Switch.
Example
To create the configuration indicated in Figure 121 and Figure 122, enter commands such as the
following.
Brocade(config)# dhcp-gateway-list 1 192.95.5.1
Brocade(config)# dhcp-gateway-list 2 200.95.6.1
Brocade(config)# dhcp-gateway-list 3 202.95.1.1 202.95.5.1
Brocade(config)# interface ethernet 2
Brocade(config-if-e1000-2)# dhcp-gateway-list 1
Brocade(config-if-e1000-2)# interface ethernet 8
Brocade(config-if-e1000-8)# dhcp-gateway-list 3
Brocade(config-if-e1000-8)# interface ethernet 14
Brocade(config-if-e1000-14)# dhcp-gateway-list 2
Syntax: dhcp-gateway-list <num> <ip-addr>
IPv4 point-to-point GRE tunnels
NOTE
This feature is supported on FCX and FastIron SX IPv6-capable devices only.
This section describes support for point-to-point Generic Routing Encapsulation (GRE) tunnels and
how to configure them on a Brocade device.
GRE tunnels support includes, but is not limited to, the following:
• IPv4 over GRE tunnels. IPv6 over GRE tunnels is not supported.
• Static and dynamic unicast routing over GRE tunnels
• Multicast routing over GRE tunnels
• Hardware forwarding of IP data traffic across a GRE tunnel.
• Path MTU Discovery (PMTUD)