CCNP-30 DHCP 3(BSCI)-优快云博客

CCNP-30 DHCP 3

实验拓扑：

实验要求：把R1配置为DHCP SERVER，把SW配置为DHCP RELAY AGENT，把R2配置为DHCP CLIENT。

试验目的：掌握交换机DHCP中继代理的配置方法。

试验配置：

R1：

DHCPSERVER(config)#service dhcp

DHCPSERVER(config)#ip dhcp pool ccnp

DHCPSERVER(dhcp-config)#network 199.99.1.0 255.255.255.0

DHCPSERVER(dhcp-config)#default-router 199.99.1.1

DHCPSERVER(dhcp-config)#dns-server 199.99.1.253 199.99.1.254

DHCPSERVER(dhcp-config)#domain-name cisco.com

DHCPSERVER(dhcp-config)#exit

DHCPSERVER(config)#ip dhcp excluded-address 199.99.1.250 199.99.1.254

DHCPSERVER(config)#int f0/0

DHCPSERVER(config-if)#ip add 199.99.1.250 255.255.255.0

DHCPSERVER(config-if)#no shu

DHCPSERVER(config-if)#exit

SW：

SW(config)#service dhcp //开启交换机的DHCP服务

SW(config)#ip dhcp relay information option //开启DHCP中继代理option82选项

SW(config)#exit

SW#vlan database

SW(vlan)#vlan 10

SW(vlan)#exit

SW#config t

SW(config)#int range f0/0 - 15

SW(config-if-range)#switchport access vlan 10

SW(config-if-range)#exit

SW(config)#int vlan 10

SW(config-if)#ip add 199.99.1.1 255.255.255.0

SW(config-if)#ip helper-address 199.99.1.250

SW(config-if)#ip dhcp relay information trusted //配置DHCP中继代理信任选项

SW(config-if)#exit

R2：

DHCPCLIENT(config)#int f0/0

DHCPCLIENT(config-if)#ip add dhcp

DHCPCLIENT(config-if)#no shu

按照上面的配置完成后，在R2上show ip int br查看一下接口是否得到了IP地址：

DHCPCLIENT#show ip int br

Interface IP-Address OK? Method Status Protocol

FastEthernet0/0 199.99.1.2 YES DHCP up up

好的，正确得到了IP地址，下面我们在SW上开启debug ip dhcp server packet，再到R2把F0/0接口shut再no shut一下，观察SW上的调试信息：

SW#debug ip dhcp server packet

SW#

*Mar 1 00:10:56.575: DHCPD: setting giaddr to 199.99.1.1.

*Mar 1 00:10:56.579: DHCPD: adding relay information option.//加入option82选项

*Mar 1 00:10:56.579: DHCPD: BOOTREQUEST from 0063.6973.636f.2d63.6330.302e.3066.3334.2e30.3030.302d.4661.302f.30 forwarded to 199.99.1.250.

*Mar 1 00:10:58.675: DHCPD: forwarding BOOTREPLY to client cc00.0f34.0000.

*Mar 1 00:10:58.675: DHCPD: validating relay information option.//通过option82选项

*Mar 1 00:10:58.675: DHCPD: broadcasting BOOTREPLY to client cc00.0f34.0000.

*Mar 1 00:10:58.679: DHCPD: Finding a relay for client 0063.6973.636f.2d63.6330.302e.3066.3334.2e30.3030.302d.4661.302f.30 on interface Vlan10.

*Mar 1 00:10:58.679: DHCPD: setting giaddr to 199.99.1.1.

*Mar 1 00:10:58.679: DHCPD: adding relay information option. //加入option82选项

*Mar 1 00:10:58.683: DHCPD: BOOTREQUEST from 0063.6973.636f.2d63.6330.302e.3066.3334.2e30.3030.302d.4661.302f.30 forwarded to 199.99.1.250.

*Mar 1 00:10:58.995: DHCPD: forwarding BOOTREPLY to client cc00.0f34.0000.

*Mar 1 00:10:58.995: DHCPD: validating relay information option. //通过option82选项

*Mar 1 00:10:58.995: DHCPD: broadcasting BOOTREPLY to client cc00.0f34.0000.

上面用红颜色标记的部分就是有关中继代理option82选项的信息，option82选项是用来验证DHCP信息的准确性的，有关option82选项的详细信息，请参照RFC3046。然后在SW上show ip dhcp relay information trusted-sources：

SW#show ip dhcp relay information trusted-sources

List of trusted sources of relay agent information option:

Vlan10

然后我们再回到R2上察看几个show命令：

DHCPCLIENT#show ip int br

Interface IP-Address OK? Method Status Protocol

FastEthernet0/0 199.99.1.3 YES DHCP up up

DHCPCLIENT#show dhcp lease

Temp IP addr: 199.99.1.3 for peer on Interface: FastEthernet0/0

Temp sub net mask: 255.255.255.0

DHCP Lease server: 199.99.1.250, state: 3 Bound

DHCP transaction id: 186E

Lease: 86400 secs, Renewal: 43200 secs, Rebind: 75600 secs

Temp default-gateway addr: 199.99.1.1

Next timer fires after: 11:59:34

Retry count: 0 Client-ID: cisco-cc00.0f34.0000-Fa0/0

Client-ID hex dump: 636973636F2D636330302E306633342E

303030302D4661302F30

Hostname: DHCPCLIENT

DHCPCLIENT#show dhcp server

DHCP server: ANY (255.255.255.255)

Leases: 2

Offers: 5 Requests: 2 Acks : 4 Naks: 0

Declines: 0 Releases: 3 Query: 0 Bad: 0

DNS0: 199.99.1.253, DNS1: 199.99.1.254

Subnet: 255.255.255.0 DNS Domain: cisco.com

DHCPCLIENT#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is 199.99.1.1 to network 0.0.0.0

C 199.99.1.0/24 is directly connected, FastEthernet0/0

S* 0.0.0.0/0 [254/0] via 199.99.1.1

得到了所有DHCP SERVER分配给它的信息，在R1上show ip dhcp binding：

DHCPSERVER#show ip dhcp binding

Bindings from all pools not associated with VRF:

IP address Client-ID/ Lease expiration Type

Hardware address/

User name

199.99.1.3 0063.6973.636f.2d63. Mar 02 2002 12:11 AM Automatic

6330.302e.3066.3334.

2e30.3030.302d.4661.

302f.30

注意用红颜色标记的部分并不是R2的F0/0接口的MAC地址，它是Client-ID，用来识别某个接口的。

实验总结：掌握基本的交换机DHCP中继代理的配置方法。

本文转自loveme2351CTO博客，原文链接：http://blog.51cto.com/loveme23/51479 ，如需转载请自行联系原作者