Brocade Communications Systems Layer 3 Routing Configuration ICX 6650 - Manual (Page 112)

94 Brocade ICX 6650 Layer 3 Routing Configuration Guide
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Configuring IP parameters – Layer 2 Switches
FIGURE 13 DHCP offers are forwarded back toward the requestors
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.
Step 4:
DHCP Server extracts the gateway
address from each packet and
assigns IP addresses for each
host within the appropriate
range.
DHCP response with IP addresses
for Subnets 1, 2, 3 and 4
Step 5:
IP addresses are distributed
to the appropriate hosts.
192.168.5.10 10.95.6.15
10.95.1.35 10.95.5.25
Host 1 Host 2
192.168.5.x
Subnet 1
10 .95.6.x
Subnet 2
Host 3 Host 4
10 .95.1.x
Subnet 3
10 .95.5.x
Subnet 4
Router
DHCP
Server
10.95.7.6
192.168.5.10
10.95.6.15
10.95.1.35
10.95.5.25
Layer 2 Switch
Hub