Advanced LDP

Lab file

39KB

Challenge - Advanced LDP.yaml

Startup configs

15KB

advanced_ldp_initial_configs.zip

archive

In this lab, you will configure more advanced LDP features. IP addressing, OSPF, and LDP are already pre-configured.

Objectve

If the R1-R3 link goes down, R1 should retain the label bindings learned from R3. Find three ways to achieve this.

R1(config)#int gi2
R1(config-if)#shut
R1(config-if)#end

R1#show mpls ldp bindings neighbor 3.3.3.3
  lib entry: 1.1.1.1/32, rev 2
        remote binding: lsr: 3.3.3.3:0, label: 16
  lib entry: 2.2.2.2/32, rev 4
        remote binding: lsr: 3.3.3.3:0, label: 17
  lib entry: 3.3.3.3/32, rev 6
        remote binding: lsr: 3.3.3.3:0, label: imp-null
  lib entry: 4.4.4.4/32, rev 8
        remote binding: lsr: 3.3.3.3:0, label: 18
  lib entry: 10.1.2.0/24, rev 10
        remote binding: lsr: 3.3.3.3:0, label: 19
  lib entry: 10.1.3.0/24, rev 18
        remote binding: lsr: 3.3.3.3:0, label: imp-null
  lib entry: 10.2.3.0/24, rev 14
        remote binding: lsr: 3.3.3.3:0, label: imp-null
  lib entry: 10.3.4.0/24, rev 16
        remote binding: lsr: 3.3.3.3:0, label: imp-null

• When R1’s Gi2 interface goes down, it should retain label bindings from neighbor R3 (3.3.3.3)

Additionally, configure the topology so that R4’s cost to 3.3.3.3/32 is 65536. You can make any change except for directly configuring the interface metrics. R4’s OSPF metrics and R3’s OSPF metrics should appear as below:

R4#show ip route 3.3.3.3 | in metric
  Known via "ospf 1", distance 110, metric 65536, type intra area
      Route metric is 65536, traffic share count is 1

R4#show ip ospf int br
Interface    PID   Area            IP Address/Mask    Cost  State Nbrs F/C
Lo0          1     0               4.4.4.4/32         1     LOOP  0/0
Gi1          1     0               10.3.4.4/24        1     P2P   1/1


R3#show ip ospf int br
Interface    PID   Area            IP Address/Mask    Cost  State Nbrs F/C
Lo0          1     0               3.3.3.3/32         1     LOOP  0/0
Gi3          1     0               10.3.4.3/24        1     P2P   1/1
Gi2          1     0               10.1.3.3/24        1     P2P   1/1
Gi1          1     0               10.2.3.3/24        1     P2P   1/1

Repeat the exercise for the XR topology.

Answers

Method 1, use LDP session protection on R1, and accept targeted hellos on R3.

Method 2, use a manually configured targeted LDP session to R3. On R3, also form a targeted session to R1 or accept targeted hellos.

Method 3, create an xconnect between R1 and R3 which will automatically form a targeted LDP neighborship.

• The simplest way to do this is go under an unused interface, no shut, and configure xconnect under the interface.

Use LDP/IGP sync on R4, and bring down the LDP neighborship between R3-R4. You can do this by setting a password on one side or perhaps using an inbound ACL denying port 646 traffic.