The protection and recovery mechanism of MPLS TE: Experimental version

The principle of the protection of TE is already mentioned. Today's focus is to explain how the Frr-fast-reroute in Te Protection is configured, and how to look at the state.

Before introducing the configuration, it is important to note that FRR fast rerouting is a protection mechanism.

Imagine if the R2 to R6 is an ordinary IGP network. After the middle link down, what is the situation?

It should be the first problem the router sends the LSA through the other interface and then reddening to the entire area.

The entire area is then recalculated, and the topology database is synchronized.

Then, with the MPLS environment, when the IGP synchronizes the topology database, MPLS LDP will re-establish the neighbor and then distribute the label, if there is traffic engineering, on the previous basis, plus RSVP. Build tunnels, send path and RESV, build neighbors.

Finally, the data will be retransmitted, that is to say, in the MPLS te environment, if there is no fast and effective protection mechanism, then the switching time will be much slower than the normal IGP. First you have to IGP convergence, then BGP convergence, MPLS LDP or RSVP work, and finally data forwarding. No one in a few seconds is not at all. That's why the introduction of FRR.

In this diagram, is the whole process of configuring FRR.

First, a one-way tunnel to the R6 is built on the R2. Then the customer side of the flow into the tunnel. Then, under the tunnel, the FRR can be quickly rerouted.

Then a MPLS te Tunnel is built on the R3 for local protection.

A local tunnel is established in the tunnel above the R3. R3--> R4--> R5. Explicit path:

Finally, the physical interface above the R3 g3/0 below. The backup link is tunnel0.

The following are the configuration and comments for each device. The configuration associated with FRR is marked with a red font.

R1 (PC-1):

Interface gigabitethernet1/0

IP Address 1.1.1.1 255.255.255.0

Negotiation Auto

!

IP Route 0.0.0.0 0.0.0.0 1.1.1.2

Simulate a PC, out of the interface address for 1.1.1.1/24, a default route all flung to the 1.1.1.2 gateway.