GRE隧道技术
掌握GRE隧道配置
GRE 隧道本身并不支持数据加密。需要其他协议如IPsec等实现数据传输加密
GRE支持广播
1.配置各台路由器的IP地址，并且使用ping命令确认个路由器的直连接口的互通。
2. 在R1和R3上配置静态路由。确保Internet网络骨干可以互通信。
在R1与R3上配置静态默认数由，不仅仅是用于模拟接入路由器。同时还为了确保在创建隧道时，隧道源与隧道目标的IP地址相互可见。以便于实现隧道。
确保R1能够ping通R3的路由器的公网接口IP
R1#ping 211.64.135.34 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 211.64.135.34, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 19/19/21 ms
在R1或R3路由器上ping路由器R3或R1的环回口。
R1#ping 192.168.1.1 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.1.1, timeout is 2 seconds: U.U.U \\\不可达消息 Success rate is 0 percent (0/5)
在R1路由器上配置GRE隧道
R1(config)#interface tunnel 0 \\启用GRE隧道 R1(config-if)#ip add 10.1.1.1 255.255.255.0 \\为隧道指定IP地址 R1(config-if)#no sh R1(config-if)#tunnel source serial 1/1 \\配置隧道的本地源端口 R1(config-if)#tunnel destination 211.64.135.34 \\配置隧道的目标端口 R1(config-if)#exit
在R3上配置GRE隧道
R3(config)#interface tunnel 0 R3(config-if)#ip address 10.1.1.2 255.255.255.0 R3(config-if)#tunnel source serial 1/0 R3(config-if)#tunnel destination 202.102.48.65 R3(config-if)#exit
在R1上查看隧道接口信息
R3#show interface tunnel 0 Tunnel0 is up, line protocol is [up] Hardware is [Tunnel] Internet address is 10.1.1.2/24 MTU 17916 bytes, BW 100 Kbit/sec, DLY 50000 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation [TUNNEL], loopback not set Keepalive not set Tunnel linestate evaluation up Tunnel source 211.64.135.34 (Serial1/0), destination 202.102.48.65 Tunnel Subblocks: src-track: Tunnel0 source tracking subblock associated with Serial1/0 Set of tunnels with source Serial1/0, 1 member (includes iterators), on interface <OK> Tunnel protocol/transport [GRE/IP] Key disabled, sequencing disabled Checksumming of packets disabled Tunnel TTL 255······
UP :当R1和R3方配置好隧道后，在本地查看隧道接口，其状态为up
Tunnel：基于隧道的接口
TUNNEL：采用了GRE隧道协议进行数据的封装。即在原始的数据包基础上，再次封装勇敢GRE的报头。
GRE/IP：隧道的协议为GRE
查看R1的路由表/
R1#show ip route Codes: L - local, 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, H - NHRP, l - LISP a - application route + - replicated route, % - next hop override Gateway of last resort is 202.102.48.66 to network 0.0.0.0 S* 0.0.0.0/0 [1/0] via 202.102.48.66 10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C 10.1.1.0/24 is directly connected, [Tunnel0] L 10.1.1.1/32 is directly connected, Tunnel0 172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks C 172.16.1.0/24 is directly connected, Loopback0 L 172.16.1.1/32 is directly connected, Loopback0 C 172.16.2.0/24 is directly connected, Loopback1 L 172.16.2.1/32 is directly connected, Loopback1 202.102.48.0/24 is variably subnetted, 2 subnets, 2 masks C 202.102.48.64/30 is directly connected, Serial1/1 L 202.102.48.65/32 is directly connected, Serial1/
Tunnel0:隧道接口的直连路由
在R1上PING路由器R3的隧道接口。
R1#ping 10.1.1.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.1.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 18/19/20 ms
R1#
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在R1和R3分别配置目标为R1和R3的回环接口，下一跳为隧道接口的路由。
R1(config)#ip route 192.168.0.0 255.255.0.0 10.1.1.2 R3(config)#ip route 172.16.0.0 255.255.0.0 10.1.1.1
再次在R1或者R3上使用PING命令，检测是否可以PING通对方的环回接口的私有网络地址。
R1#ping 192.168.1.1 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.1.1, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 19/19/20 ms R1#ping 192.168.2.1 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.2.1, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 17/19/21 ms R1#
还可以使用如下命令，查看GRE隧道的其他信息。
R1#show interface tunnel 0 stats Tunnel0 Switching path Pkts In Chars In Pkts Out Chars Out Processor 15 1860 18 2076 Route cache 0 0 0 0 Total 15 1860 18 2076 R1#
实验完成
