CCNP-30 DHCP 3(BSCI)

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。

本文出自 “★Beckham~23” 博客，请务必保留此出处http://loveme23.blog.51cto.com/7891/51479