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Example: MPLS LSP Link Protection Configuration

Figure 10: MPLS LSP Link Protection Topology Diagram

Image g017144.gif

In Figure 10, a primary MPLS LSP is established from Router 1 through Router 3 to destination Router 2. To implement link protection, include the link-protection statement on the primary LSP at the ingress point and on the appropriate downstream RSVP interfaces you wish to protect. In this case, the primary LSP named Protected_LSP on Router 1 requires link protection, as does the so-7/3/2 RSVP interface of Router 1 and the so-6/0/0 RSVP interface of Router 3. After link protection is enabled for the protected LSP, bypass LSPs are established automatically for the LSP-traversed interfaces of Routers 1 and 3.

On Router 1, configure an interior gateway protocol (IGP) routing protocol (in this case, IS-IS), RSVP, and MPLS on the so-0/0/0 and so-7/3/2 interfaces. Next, configure the primary LSP on Router 1 to point to the loopback address of Router 2. The primary LSP’s strict path must travel though Router 3.

Enable link protection on both the LSP itself and the outgoing RSVP interface traversed by the primary LSP (in this case, the so-7/3/2 RSVP interface of Router 1). After you enable link protection, the router notices that the primary LSP is protected and prepares a bypass LSP.

Configure a static route of 10.31.5.1 in the LSP on Router 1. You can use this route for testing purposes. Also, if you want to enable Packet Forwarding Engine local repair, establish a policy that requires all traffic to use per-packet load balancing. Once this policy is configured, export it to the neighboring routers with the export statement at the [edit routing-options forwarding-table] hierarchy level.

Router 1



[edit]
interfaces {


so-0/0/0 {


unit 0 {


family inet {
address 10.31.3.1/30;
}


family iso;
family mpls;
}


}




so-7/3/2 {


unit 0 {


family inet {
address 10.31.1.1/30;
}


family iso;
family mpls;
}


}




lo0 {


unit 0 {


family inet {
address 10.245.71.51/32;
}




family iso {
}


}


}




protocols {


rsvp {


interface so-7/3/2.0 {
                     
link-protection; # Enable link protection on the interface carrying the main LSP.
}




interface so-0/0/0.0 {
}




mpls {


label-switched-path Protected_LSP {
to 10.245.71.52;
                       
install 10.31.5.1/32
active; # This route is used for testing the LSPs.
                       
link-protection;            # Enable link protection on the protected LSP.
primary path1;
}




path path1 {
10.31.1.2 strict;
}


interface so-0/0/0.0;
interface so-7/3/2.0;
}




isis {
level 2 wide-metrics-only;


interface so-0/0/0.0 {
level 1 disable;


level 2 {
metric 100;
te-metric 100;
}


}




interface so-7/3/2.0 {
level 1 disable;


level 2 {
metric 10;
te-metric 10;
}


}




interface lo0.0 {
passive;
}


}


}




routing-options {


forwarding-table { # Apply this policy to the forwarding
table only
                     
export pplb; # if Packet Forwarding Engine local repair is needed.
}


}




policy-options {



policy-statement pplb {




then {# Configure this policy
only if

load-balance per-packet; # Packet
Forwarding Engine local repair is needed.
}


}


}


}


}

On Router 2, no link protection configuration is needed. However, you should configure MPLS, RSVP, and IS-IS to communicate with the other routers.

Router 2



[edit]
interfaces {


so-0/0/0 {


unit 0 {


family inet {
address 10.31.3.2/30;
}


family iso;
family mpls;
}


}




so-7/1/0 {


unit 0 {


family inet {
address 10.31.2.1/30;
}


family iso;
family mpls;
}


}




lo0 {


unit 0 {


family inet {
address 10.245.71.53/32;
}




family iso {
}


}


}




protocols {



rsvp {

interface so-0/0/0.0;
interface so-7/1/0.0;
}





mpls {

interface so-0/0/0.0;
interface so-7/1/0.0;
}





isis {

level 2 wide-metrics-only;


interface so-0/0/0.0 {
level 1 disable;


level 2 {
metric 100;
te-metric 100;
}


}




interface so-7/1/0.0 {
level 1 disable;


level 2 {
metric 10;
te-metric 10;
}


}




interface lo0.0 {
passive;
}


}


}


}

On Router 3, include IS-IS, RSVP, and MPLS on the so-1/0/0 and so-6/0/0 interfaces. Enable link protection on the remaining RSVP interface traversed by the primary LSP (in this case, the so-6/0/0 RSVP interface). After you enable link protection, the router notices the primary LSP is protected and prepares a bypass LSP.

To enable Packet Forwarding Engine local repair, establish a policy that requires traffic to use per-packet load balancing. Once this policy is configured, export it to the neighboring routers.

Router 3



[edit]
interfaces {


so-1/0/0 {


unit 0 {


family inet {
address 10.31.1.2/30;
}


family iso;
family mpls;
}


}




so-6/0/0 {


unit 0 {


family inet {
address 10.31.2.2/30;
}


family iso;
family mpls;
}


}




lo0 {


unit 0 {


family inet {
address 10.245.271.53/32;
}




family iso {
}


}


}




protocols {


rsvp {
interface so-1/0/0.0;


interface so-6/0/0.0 { # Primary interface going to Router
2.
                     
link-protection;                   

}


}




mpls {
interface so-1/0/0.0;
interface so-6/0/0.0;
}




isis {
level 2 wide-metrics-only;


interface so-1/0/0.0 {
level 1 disable;


level 2 {
metric 10;
te-metric 10;
}


}




interface so-6/0/0.0 {
level 1 disable;


level 2 {
metric 10;
te-metric 10;
}


}




interface lo0.0 {
passive;
}


}


}




policy-options {



policy-statement pplb {




then {


load-balance per-packet; # If
Packet Forwarding Engine local repair is needed.
}


}


}




routing-options {


forwarding-table {

export pplb;       # If Packet
Forwarding Engine local repair is needed.
}


}


}

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