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Configuring a GRE Tunnel Interface Between PE Routers

This example shows how to configure a generic routing encapsulation (GRE) tunnel interface between PE routers to provide VPN connectivity. You can use this configuration to tunnel VPN traffic across a non-MPLS core network. The network topology used in this example is shown in Figure 1. The P routers shown in this illustration do not run MPLS.

Figure 1: PE Routers A and D Connected by a GRE Tunnel Interface

PE Routers A and D Connected by a GRE Tunnel Interface

For configuration information, see the following sections:

Configuring the Routing Instance on Router A

Configure a routing instance on Router A:

[edit routing-instances]
gre-config {instance-type vrf;interface fe-1/0/0.0;route-distinguisher 10.255.14.176:69;vrf-import import-config;vrf-export export-config;protocols {ospf {export import-config;area 0.0.0.0 {interface all;}}}}

Configuring the Routing Instance on Router D

Configure a routing instance on Router D:

[edit routing-instances]
gre-config {instance-type vrf;interface fe-1/0/1.0;route-distinguisher 10.255.14.178:69;vrf-import import-config;vrf-export export-config;protocols {ospf {export import-config;area 0.0.0.0 {interface all;}}}}

Configuring MPLS, BGP, and OSPF on Router A

Although you do not need to configure MPLS on the P routers in this example, it is needed on the PE routers for the interface between the PE and CE routers and on the GRE interface (gr-1/1/0.0) linking the PE routers (Router A and Router D). Configure MPLS, BGP, and OSPF on Router A:

[edit protocols]
mpls {interface all;}
bgp {group pe-to-pe {type internal;neighbor 10.255.14.178 {family inet-vpn {unicast;}}}}
ospf {area 0.0.0.0 {interface all;interface gr-1/1/0.0 {disable;}}}

Configuring MPLS, BGP, and OSPF on Router D

Although you do not need to configure MPLS on the P routers in this example, it is needed on the PE routers for the interface between the PE and CE routers and on the GRE interface (gr-1/1/0.0) linking the PE routers (Router D and Router A). Configure MPLS, BGP, and OSPF on Router D:

[edit protocols]
mpls {interface all;}
bgp {group pe-to-pe {type internal;neighbor 10.255.14.176 {family inet-vpn {unicast;}}}}
ospf {traffic-engineering;area 0.0.0.0 {interface all;interface fxp0.0 {disable;}interface gr-1/1/0.0 {disable;}}}

Configuring the Tunnel Interface on Router A

Configure the tunnel interface on Router A (the tunnel is unnumbered):

[edit interfaces interface-name]
unit 0 {tunnel {source 10.255.14.176;destination 10.255.14.178;}family inet;family mpls;}

Configuring the Tunnel Interface on Router D

Configure the tunnel interface on Router D (the tunnel is unnumbered):

[edit interfaces interface-name]
unit 0 {tunnel {source 10.255.14.178;destination 10.255.14.176;}family inet;family mpls;}

Configuring the Routing Options on Router A

As part of the routing options configuration for Router A, you need to configure routing table groups to enable VPN route resolution in the inet.3 routing table.

Configure the routing options on Router A:

[edit routing-options]
interface-routes {rib-group inet if-rib;}
rib inet.3 {static {route 10.255.14.178/32 next-hop gr-1/1/0.0;}}
rib-groups {if-rib {import-rib [ inet.0 inet.3 ];}}

Configuring the Routing Options on Router D

As part of the routing options configuration for Router D, you need to configure routing table groups to enable VPN route resolution in the inet.3 routing table.

Configure the routing options on Router D:

[edit routing-options]
interface-routes {rib-group inet if-rib;}
rib inet.3 {static {route 10.255.14.176/32 next-hop gr-1/1/0.0;}}
rib-groups {if-rib {import-rib [ inet.0 inet.3 ];}}

Configuration Summary for Router A

Configure the Routing Instance

gre-config {instance-type vrf;interface fe-1/0/0.0;route-distinguisher 10.255.14.176:69;vrf-import import-config;vrf-export export-config;protocols {ospf {export import-config;area 0.0.0.0 {interface all;}}}}

Configure MPLS

mpls {interface all;}

Configure BGP

bgp {traceoptions {file bgp.trace world-readable;flag update detail;}group pe-to-pe {type internal;neighbor 10.255.14.178 {family inet-vpn {unicast;}}}}

Configure OSPF

ospf {area 0.0.0.0 {interface all;interface gr-1/1/0.0 {disable;}}}

Configure the Tunnel Interface

interface-name {unit 0 {tunnel {source 10.255.14.176;destination 10.255.14.178;}family inet;family mpls;}}

Configure Routing Options

interface-routes {rib-group inet if-rib;}
rib inet.3 {static {route 10.255.14.178/32 next-hop gr-1/1/0.0;}}
rib-groups {if-rib {import-rib [ inet.0 inet.3 ];}}

Configuration Summary for Router D

Configure the Routing Instance

gre-config {instance-type vrf;interface fe-1/0/1.0;route-distinguisher 10.255.14.178:69;vrf-import import-config;vrf-export export-config;protocols {ospf {export import-config;area 0.0.0.0 {interface all;}}}}

Configure MPLS

mpls {interface all;}

Configure BGP

bgp {group pe-to-pe {type internal;neighbor 10.255.14.176 {family inet-vpn {unicast;}}}}

Configure OSPF

ospf {traffic-engineering;area 0.0.0.0 {interface all;interface fxp0.0 {disable;}interface gr-1/1/0.0 {disable;}}}

Configure the Tunnel Interface

interface-name {unit 0 {tunnel {source 10.255.14.178;destination 10.255.14.176;}family inet;family mpls;}}

Configure the Routing Options

interface-routes {rib-group inet if-rib;}
rib inet.3 {static {route 10.255.14.176/32 next-hop gr-1/1/0.0;}}
rib-groups {if-rib {import-rib [ inet.0 inet.3 ];}}

Published: 2013-02-28

Supported Platforms

Published: 2013-02-28

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