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	Merge pull request #33 from mic54/master
Restructured Tunnel Interface added GRE
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							| @ -0,0 +1,115 @@ | ||||
| .. _interfaces-tunnel: | ||||
| 
 | ||||
| Tunnel Interfaces | ||||
| ================= | ||||
| 
 | ||||
| Generic Routing Encapsulation (GRE) | ||||
| ----------------------------------- | ||||
| 
 | ||||
| A GRE tunnel operates at layer 3 of the OSI model and is repsented by IP protocol 47.  The  | ||||
| main benefit of a GRE tunnel is that you are able to route traffic across disparate networks.   | ||||
| GRE also supports multicast traffic and supports routing protocols that leverage multicast to  | ||||
| form neighbor adjacencies. | ||||
| 
 | ||||
| Configuration | ||||
| ^^^^^^^^^^^^^ | ||||
| 
 | ||||
| A basic configuration requires a tunnel source (local-ip), a tunnel destination (remote-ip),  | ||||
| an encapsulation type (gre), and an address (ipv4/ipv6).  Below is a configuration example  | ||||
| taken from a VyOS router and a Cisco IOS router.  The main difference between these two  | ||||
| configurations is that VyOS requires you explicitly configure the encapsulation type.   | ||||
| The Cisco router defaults to 'gre ip' otherwise it would have to be configured as well. | ||||
| 
 | ||||
| **VyOS Router:** | ||||
| 
 | ||||
| .. code-block:: sh | ||||
| 
 | ||||
|   set interfaces tunnel tun100 address '10.0.0.1/30' | ||||
|   set interfaces tunnel tun100 encapsulation 'gre' | ||||
|   set interfaces tunnel tun100 local-ip '198.18.0.2' | ||||
|   set interfaces tunnel tun100 remote-ip '198.18.2.2' | ||||
| 
 | ||||
| **Cisco IOS Router:** | ||||
| 
 | ||||
| .. code-block:: sh | ||||
| 
 | ||||
|   interface Tunnel100 | ||||
|   ip address 10.0.0.2 255.255.255.252 | ||||
|   tunnel source 198.18.2.2 | ||||
|   tunnel destination 198.18.0.2 | ||||
| 
 | ||||
| Troubleshooting | ||||
| ^^^^^^^^^^^^^^^ | ||||
| 
 | ||||
| GRE is a well defined standard that is common in most networks.  While not inherently difficult  | ||||
| to configure there are a couple of things to keep in mind to make sure the configuration performs  | ||||
| as expected.  A common cause for GRE tunnels to fail to come up correctly include ACL or Firewall  | ||||
| configurations that are discarding IP protocol 47 or blocking your source/desintation traffic. | ||||
| 
 | ||||
| **1. Confirm IP connectivity between tunnel local-ip and remote-ip:** | ||||
| 
 | ||||
| .. code-block:: sh | ||||
| 
 | ||||
|   vyos@vyos:~$ ping 198.18.2.2 interface 198.18.0.2 count 4 | ||||
|   PING 198.18.2.2 (198.18.2.2) from 198.18.0.2 : 56(84) bytes of data. | ||||
|   64 bytes from 198.18.2.2: icmp_seq=1 ttl=254 time=0.807 ms | ||||
|   64 bytes from 198.18.2.2: icmp_seq=2 ttl=254 time=1.50 ms | ||||
|   64 bytes from 198.18.2.2: icmp_seq=3 ttl=254 time=0.624 ms | ||||
|   64 bytes from 198.18.2.2: icmp_seq=4 ttl=254 time=1.41 ms | ||||
| 
 | ||||
|   --- 198.18.2.2 ping statistics --- | ||||
|   4 packets transmitted, 4 received, 0% packet loss, time 3007ms | ||||
|   rtt min/avg/max/mdev = 0.624/1.087/1.509/0.381 ms | ||||
| 
 | ||||
| **2. Confirm the link type has been set to GRE:** | ||||
| 
 | ||||
| .. code-block:: sh | ||||
| 
 | ||||
|   vyos@vyos:~$ show interfaces tunnel tun100 | ||||
|   tun100@NONE: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1476 qdisc noqueue state UNKNOWN group default qlen 1000 | ||||
|     link/gre 198.18.0.2 peer 198.18.2.2 | ||||
|     inet 10.0.0.1/30 brd 10.0.0.3 scope global tun100 | ||||
|        valid_lft forever preferred_lft forever | ||||
|     inet6 fe80::5efe:c612:2/64 scope link | ||||
|        valid_lft forever preferred_lft forever | ||||
| 
 | ||||
|     RX:  bytes    packets     errors    dropped    overrun      mcast | ||||
|           2183         27          0          0          0          0 | ||||
|     TX:  bytes    packets     errors    dropped    carrier collisions | ||||
|            836          9          0          0          0          0 | ||||
| 
 | ||||
| **3. Confirm IP connectivity across the tunnel:** | ||||
| 
 | ||||
| .. code-block:: sh | ||||
| 
 | ||||
|   vyos@vyos:~$ ping 10.0.0.2 interface 10.0.0.1 count 4 | ||||
|   PING 10.0.0.2 (10.0.0.2) from 10.0.0.1 : 56(84) bytes of data. | ||||
|   64 bytes from 10.0.0.2: icmp_seq=1 ttl=255 time=1.05 ms | ||||
|   64 bytes from 10.0.0.2: icmp_seq=2 ttl=255 time=1.88 ms | ||||
|   64 bytes from 10.0.0.2: icmp_seq=3 ttl=255 time=1.98 ms | ||||
|   64 bytes from 10.0.0.2: icmp_seq=4 ttl=255 time=1.98 ms | ||||
| 
 | ||||
|   --- 10.0.0.2 ping statistics --- | ||||
|   4 packets transmitted, 4 received, 0% packet loss, time 3008ms | ||||
|   rtt min/avg/max/mdev = 1.055/1.729/1.989/0.395 ms | ||||
| 
 | ||||
| Virtual Tunnel Interface (VTI) | ||||
| ------------------------------ | ||||
| 
 | ||||
| Set Virtual Tunnel Interface | ||||
| 
 | ||||
| .. code-block:: sh | ||||
| 
 | ||||
|   set interfaces vti vti0 address 192.168.2.249/30 | ||||
|   set interfaces vti vti0 address 2001:db8:2::249/64 | ||||
| 
 | ||||
| Results in: | ||||
| 
 | ||||
| .. code-block:: sh | ||||
| 
 | ||||
|   vyos@vyos# show interfaces vti | ||||
|   vti vti0 { | ||||
|       address 192.168.2.249/30 | ||||
|       address 2001:db8:2::249/64 | ||||
|       description "Description" | ||||
|   } | ||||
| @ -1,22 +0,0 @@ | ||||
| .. _interfaces-vti: | ||||
| 
 | ||||
| Tunnel Interfaces (vti) | ||||
| ----------------------- | ||||
| 
 | ||||
| Set Virtual Tunnel interface | ||||
| 
 | ||||
| .. code-block:: sh | ||||
| 
 | ||||
|   set interfaces vti vti0 address 192.168.2.249/30 | ||||
|   set interfaces vti vti0 address 2001:db8:2::249/64 | ||||
| 
 | ||||
| Results in: | ||||
| 
 | ||||
| .. code-block:: sh | ||||
| 
 | ||||
|   vyos@vyos# show interfaces vti | ||||
|   vti vti0 { | ||||
|       address 192.168.2.249/30 | ||||
|       address 2001:db8:2::249/64 | ||||
|       description "Description" | ||||
|   } | ||||
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