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CHAPTER 5
Configuring a LAN with DHCP and VLANs
The Cisco 1800 series integrated services fixed-configuration routers support clients on both physical
LANs and virtual LANs (VLANs). The routers can use the Dynamic Host Configuration Protocol
(DHCP) to enable automatic assignment of IP configurations for nodes on these networks.
Figure 5-1 shows a typical deployment scenario with two physical LANs connected by the router and
two VLANs.
Figure 5-1 Physical and Virtual LANs with DHCP Configured on t
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Chapter 5 Configuring a LAN with DHCP and VLANs Configure DHCP When you configure a DHCP server, you must configure the server properties, policies, and DHCP options. Note Whenever you change server properties, you must reload the server with the configuration data from the Network Registrar database. VLANs The Cisco 1800 series integrated services routers (fixed) support eight Fast Ethernet ports on which you can configure VLANs. VLANs enable networks to be segmented and formed into logi
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Chapter 5 Configuring a LAN with DHCP and VLANs Configure DHCP Command Purpose Step 3 ip dhcp excluded-address low-address Specifies IP addresses that the DHCP server should [high-address] not assign to DHCP clients. In this example, we are excluding the router address. Example: Router(config)# ip dhcp excluded-address 192.168.9.0 Step 4 ip dhcp pool name Creates a DHCP address pool on the router and enters DHCP pool configuration mode. The name Example: argument can be a string or an int
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Chapter 5 Configuring a LAN with DHCP and VLANs Configure DHCP Configuration Example The following configuration example shows a portion of the configuration file for the DCHP configuration described in this chapter. ip dhcp excluded-address 192.168.9.0 ! ip dhcp pool dpool1 import all network 10.10.0.0 255.255.255.0 default-router 10.10.10.10 dns-server 192.168.35.2 domain-name cisco.com ! ip domain name smallbiz.com ip name-server 192.168.11.12 Verify Your DHCP Configurat
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Chapter 5 Configuring a LAN with DHCP and VLANs Configure VLANs Message Sent BOOTREPLY 0 DHCPOFFER 0 DHCPACK 0 DHCPNAK 0 Router# Configure VLANs Perform these steps to configure VLANs on your router, beginning in privileged EXEC mode: Command Purpose Step 1 vlan database Enters VLAN configuration mode. Example: Router# vlan database Router(vlan)# Step 2 vlan vlan-id [media type] [name vlan-name] Adds VLANs, with identifiers rang
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Chapter 5 Configuring a LAN with DHCP and VLANs Configure VLANs Verify Your VLAN Configuration Use the following commands to view your VLAN configuration. • show—Entered from VLAN database mode. Displays summary configuration information for all configured VLANs. • show vlan-switch—Entered from privileged EXEC mode. Displays detailed configuration information for all configured VLANs. Router# vlan database Router(vlan)# show VLAN ISL Id: 1 Name: default Media Type: Ethernet
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Chapter 5 Configuring a LAN with DHCP and VLANs Configure VLANs Bridge Type: SRB Bridge Number: 1 STP Type: IBM Router# show vlan-switch VLAN Name Status Ports ---- -------------------------------- --------- ------------------------------- 1 default active Fa0, Fa1, Fa2, Fa3 1002 fddi-default active 1003 token-ring-default active 1004 fddinet-default active 1005 trn
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Chapter 5 Configuring a LAN with DHCP and VLANs Configure VLANs Cisco 1800 Series Integrated Services Routers (Fixed) Software Configuration Guide 5-8 OL-6426-02
