Dhcp Server - Brocade Communications Systems FastIron SX 800 Configuration Manual

Configuring IP parameters - Layer 3 switches
To change the IP address used for stamping BootP/DHCP requests received on interface 1/1/1, enter commands such as the following.
device(config)# interface ethernet 1/1/1
device(config-if-1/1/1)# ip bootp-gateway 10.157.22.26
These commands change the CLI to the configuration level for port 1/1/1, then change the BootP/DHCP stamp address for requests
received on port 1/1/1 to 10.157.22.26. The Layer 3 switch will place this IP address in the Gateway Address field of BootP/DHCP
requests that the Layer 3 switch receives on port 1/1/1 and forwards to the BootP/DHCP server.
Syntax: ip bootp-gateway ip-addr
Changing the maximum number of hops to a BootP relay server
Each BootP or DHCP request includes a field Hop Count field. The Hop Count field indicates how many routers the request has passed
through. When the Layer 3 switch receives a BootP/DHCP request, the Layer 3 switch looks at the value in the Hop Count field:
• If the hop count value is equal to or less than the maximum hop count the Layer 3 switch allows, the Layer 3 switch increments
the hop count by one and forwards the request.
• If the hop count is greater than the maximum hop count the Layer 3 switch allows, the Layer 3 switch discards the request.
To change the maximum number of hops the Layer 3 switch allows for forwarded BootP/DHCP requests, use either of the following
methods.
NOTE
The BootP and DHCP hop count is not the TTL parameter.
To modify the maximum number of BootP/DHCP hops, enter the following command.
device(config)# bootp-relay-max-hops 10
This command allows the Layer 3 switch to forward BootP/DHCP requests that have passed through ten previous hops before reaching
the Layer 3 switch. Requests that have traversed 11 hops before reaching the switch are dropped. Since the hop count value initializes at
zero, the hop count value of an ingressing DHCP Request packet is the number of Layer 3 routers that the packet has already traversed.
Syntax: bootp-relay-max-hops max-hops
The max-hops parameter value can be 1 through 15.

DHCP server

All FastIron devices can be configured to function as DHCP servers.
Dynamic Host Configuration Protocol (DHCP) is a computer networking protocol used by devices (DHCP clients) to obtain leased (or
permanent) IP addresses. DHCP is an extension of the Bootstrap Protocol (BootP). The differences between DHCP and BootP are the
address allocation and renewal process.
DHCP introduces the concept of a lease on an IP address. The DHCP server can allocate an IP address for a specified amount of time or
can extend a lease for an indefinite amount of time. DHCP provides greater control of address distribution within a subnet. This feature is
crucial if the subnet has more devices than available IP addresses. In contrast to BootP, which has two types of messages that can be
used for leased negotiation, DHCP provides seven types of messages.
DHCP allocates temporary or permanent network IP addresses to clients. When a client requests the use of an address for a time
interval, the DHCP server guarantees not to reallocate that address within the requested time and tries to return the same network
address each time the client makes a request. The period of time for which a network address is allocated to a client is called a lease. The
client may extend the lease through subsequent requests. When the client is done with the address, they can release the address back to
the server. By asking for an indefinite lease, clients may receive a permanent assignment.
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FastIron Ethernet Switch Layer 3 Routing
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