GRE between Router and linux

1.拓撲圖

<a href="http://blog.51cto.com/attachment/201204/153838172.jpg" target="_blank"></a>

2.基本接口配置：

R1：

R1(config)#int e0/0

R1(config-if)#ip add 10.1.1.1 255.255.255.0

R1(config-if)#no sh

R2:

R2(config)#int e0/0

R2(config-if)#ip add 10.1.1.2 255.255.255.0

R2(config-if)#no sh

R2(config)#int e0/1

R2(config-if)#ip add 202.100.1.2 255.255.255.0

R3:

R3(config)#int e0/0

R3(config-if)#ip add 202.100.1.3 255.255.255.0

R3(config-if)#no sh

R3(config)#int e0/1

R3(config-if)#ip add 202.100.2.3 255.255.255.0

C1:

eth0: 202.100.1.10/24

eth1:10.1.2.10/24

PC:

eth0:10.1.2.10/24

3.路由配置：

R1(config)#ip route 0.0.0.0 0.0.0.0 10.1.1.2

R2(config)#ip route 0.0.0.0 0.0.0.0 202.100.1.3

C1:Default GateWay  202.100.2.3

PC：Default GateWay  10.1.2.10

4.GRE配置

R3：

R2(config)#int tun 0

R2(config-if)#ip add 172.16.1.1 255.255.255.252

R2(config-if)#tunnel source 202.100.1.2

R2(config-if)#tun

R2(config-if)#tunnel de

R2(config-if)#tunnel destination 202.100.2.10

R2(config-if)#end

R2(config)#ip route 10.1.2.0 255.255.255.0 tunnel 0

C1：

A.确定是否加載了GRE子產品

[root@cluster01 ~]# lsmod |grep ip_gre

B.加載GRE子產品

[root@cluster01 ~]# insmod /lib/modules/2.6.18-

2.6.18-159.el5/     2.6.18-238.9.1.el5/ 2.6.18-92.1.10.el5/

2.6.18-164.el5/     2.6.18-238.el5/     

[root@cluster01 ~]# uname -an

Linux cluster01 2.6.18-238.9.1.el5 #1 SMP Tue Apr 12 18:10:56 EDT 2011 i686 i686 i386 GNU/Linux

[root@cluster01 ~]# insmod

insmod         insmod.static  

[root@cluster01 ~]# insmod /lib/modules/2.6.18-238.9.1.el5/kernel/net/ipv4/ip

ipcomp.ko  ip_gre.ko  ipip.ko    ipvs/      

[root@cluster01 ~]# insmod /lib/modules/2.6.18-238.9.1.el5/kernel/net/ipv4/ip_gre.ko 

C.GRE tunnel接口配置

[root@cluster01 ~]# ip tunnel add tunnel0 mode gre remote 202.100.1.2 local 202.100.2.10 ttl 225

[root@cluster01 ~]# ip link set tunnel0 up mtu 1500

[root@cluster01 ~]# ip addr add 172.16.1.2/30 peer 172.16.1.1/30 dev tunnel0

[root@cluster01 ~]# ip route add 10.1.1.0/24 dev tunnel0

D.驗證GRE接口

[root@cluster01 ~]# ip addr show

1: lo: &lt;LOOPBACK,UP,LOWER_UP&gt; mtu 16436 qdisc noqueue 

    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

    inet 127.0.0.1/8 scope host lo

    inet6 ::1/128 scope host 

       valid_lft forever preferred_lft forever

2: eth0: &lt;BROADCAST,MULTICAST,UP,LOWER_UP&gt; mtu 1500 qdisc pfifo_fast qlen 1000

    link/ether 00:0c:29:27:7d:b8 brd ff:ff:ff:ff:ff:ff

    inet 202.100.2.10/24 brd 202.100.2.255 scope global eth0

    inet6 fe80::20c:29ff:fe27:7db8/64 scope link 

3: eth1: &lt;BROADCAST,MULTICAST,UP,LOWER_UP&gt; mtu 1500 qdisc pfifo_fast qlen 1000

    link/ether 00:0c:29:27:7d:c2 brd ff:ff:ff:ff:ff:ff

    inet 10.1.2.10/24 brd 10.1.2.255 scope global eth1

    inet6 fe80::20c:29ff:fe27:7dc2/64 scope link 

4: sit0: &lt;NOARP&gt; mtu 1480 qdisc noop 

    link/sit 0.0.0.0 brd 0.0.0.0

5: gre0: &lt;NOARP&gt; mtu 1476 qdisc noop 

    link/gre 0.0.0.0 brd 0.0.0.0

6: tunnel0@NONE: &lt;POINTOPOINT,NOARP,UP,LOWER_UP&gt; mtu 1500 qdisc noqueue 

    link/gre 202.100.2.10 peer 202.100.1.2

    inet 172.16.1.2 peer 172.16.1.1/30 scope global tunnel0

[root@cluster01 ~]# ip link show

[root@cluster01 ~]# ip route show

172.16.1.0/30 dev tunnel0  proto kernel  scope link  src 172.16.1.2 

202.100.2.0/24 dev eth0  proto kernel  scope link  src 202.100.2.10 

10.1.1.0/24 dev tunnel0  scope link 

10.1.2.0/24 dev eth1  proto kernel  scope link  src 10.1.2.10 

169.254.0.0/16 dev eth1  scope link 

default via 202.100.2.3 dev eth0 

E.開啟路由轉發

[root@cluster01 ~]# echo 1 &gt; /proc/sys/net/ipv4/ip_forward

本文轉自 碧雲天 51CTO部落格，原文連結：http://blog.51cto.com/333234/846702，如需轉載請自行聯系原作者