© 2006 Cisco Systems, Inc. All rights reserved. BSCI v Manipulating Routing Updates Implementing Advanced Cisco IOS Features: Configuring DHCP

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v DHCP in an Enterprise Network

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v Dynamic Host Configuration Protocol

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v Configuring a DHCP Server Router(config)#ip dhcp pool [pool name] Enables a DHCP pool for use by hosts Router(config-dhcp)#import all Imports DNS and WINS information from IPCP Router(config-dhcp)#default-router [host address] Specifies the default router for the pool to use Router(config-dhcp)#network [network address][subnet mask] Specifies the network and subnet mask of the pool

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v DHCP Server Configuration Example ipdhcp database write-delay 120 ip dhcp excluded-address ip dhcp excluded-address ip dhcp pool 0 network /16 domain-name global.com dns-server netbios-name-server default-router

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v Importing and Autoconfiguration

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v DHCP Client Router (config-if)# ip address dhcp Enables a Cisco IOS device to obtain an IP address dynamically from a DHCP server

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v Helper Addressing Overview Routers do not forward broadcasts, by default. Helper address provides selective connectivity.

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v Why Use a Helper Address? Sometimes clients do not know the server address. Helpers change broadcast to unicast to reach server.

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v IP Helper Address Commands Specifies which protocols will be forwarded Router(config)# ip forward-protocol { udp [ port ] } Enables forwarding and specifies destination address for main UDP broadcast packets Changes destination address from broadcast to unicast or directed broadcast address Router(config-if)# ip helper-address address

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v Multiple Servers: Remote Networks

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v Relay Agent Option Support

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v show ip dhcp database router# Displays recent activity on the DHCP database DHCP Verification Commands show ip dhcp server statistics router# Shows count information about statistics and messages sent and received show ip route dhcp router# Displays routes added to the routing table by DHCP debug ip dhcp server {events | packets | linkage} router# Enables debugging on the DHCP server

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v Summary DHCP functions may be configured with Cisco IOS software. DHCP server can be configured. DHCP options can be configured. DHCP client can be configured. The IP helper address activates the DHCP relay agent in the Cisco IOS device. DHCP relay services are supported.

© 2006 Cisco Systems, Inc. All rights reserved. BSCI v