Brocade TurboIron 24X Series Configuration Guide - Manual (Page 522)

488 Brocade TurboIron 24X Series Configuration Guide
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Configuring IP parameters – Layer 2 Switches
Syntax: ip ttl <1-255>
Configuring DHCP Assist
DHCP Assist allows a Layer 2 Switch to assist a router that is performing multi-netting on its
interfaces as part of its DHCP relay function.
DHCP Assist ensures that a DHCP server that manages multiple IP subnets can readily recognize
the requester IP subnet, even when that server is not on the client local LAN segment. The Layer 2
Switch does so by stamping each request with its IP gateway address in the DHCP discovery packet.
By allowing multiple subnet DHCP requests to be sent on the same wire, you can reduce the
number of router ports required to support secondary addressing as well as reduce the number of
DHCP servers required, by allowing a server to manage multiple subnet address assignments.
FIGURE 61 DHCP requests in a network without DHCP Assist on the Layer 2 Switch
In a network operating without DHCP Assist, hosts can be assigned IP addresses from the wrong
subnet range because a router with multiple subnets configured on an interface cannot distinguish
among DHCP discovery packets received from different subnets.