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OSPF Sham-Link Support for MPLS VPN
Configuration Tasks
11
Cisco IOS Release 12.2(8)T
To create a sham-link, use the following commands starting in EXEC mode:
Verifying Sham-Link Creation
To verify that the sham-link was successfully created and is operational, use the show ip ospf
sham-links command in EXEC mode:
Router1# show ip ospf sham-links
Sham Link OSPF_SL0 to address 10.2.1.2 is up
Area 1 source address 10.2.1.1
Run as demand circuit
DoNotAge LSA allowed. Cost of using 40 State POINT_TO_POINT,
Command Purpose
Step 1
Router1# configure terminal
Enters global configuration mode on the first PE router.
Step 2
Router1(config)# interface loopback
interface-number
Creates a loopback interface to be used as an endpoint of the
sham-link on PE-1 and enters interface configuration mode.
Step 3
Router1(config-if)# ip vrf forwarding
vrf-name
Associates the loopback interface with a VRF. Removes the IP
address.
Step 4
Router1(config-if)# ip address
ip-address
mask
Reconfigures the IP address of the loopback interface on PE-1.
Step 5
Router1(config-if)# end
Returns to global configuration mode.
Step 6
Router1(config)# end
Returns to EXEC mode.
Step 7
Router2# configure terminal
Enters global configuration mode on the second PE router.
Step 8
Router2(config)# interface loopback
interface-number
Creates a loopback interface to be used as the endpoint of the
sham-link on PE-2 and enters interface configuration mode.
Step 9
Router2(config-if)# ip vrf forwarding
vrf-name
Associates the second loopback interface with a VRF. Removes
the IP address.
Step 10
Router2(config-if)# ip address
ip-address
mask
Reconfigures the IP address of the loopback interface on PE-2.
Step 11
Router2(config-if)# end
Returns to global configuration mode.
Step 12
Router1(config)# end
Returns to EXEC mode.
Step 13
Router1(config)# router ospf
process-id
vrf
vrf-name
Configures the specified OSPF process with the VRF associated
with the sham-link interface on PE-1 and enters interface
configuration mode.
Step 14
Router1(config-if)# area
area-id
sham-link
source-address
destination-address
cost
number
Configures the sham-link on the PE-1 interface within a specified
OSPF area and with the loopback interfaces specified by the IP
addresses as endpoints. cost number configures the OSPF cost for
sending an IP packet on the PE-1 sham-link interface.
Step 15
Router2(config)# router ospf
process-id
vrf
vrf-name
Configures the specified OSPF process with the VRF associated
with the sham-link interface on PE-2 and enters interface
configuration mode.
Step 16
Router2(config-if)# area
area-id
sham-link
source-address
destination-address
cost
number
Configures the sham-link on the PE-2 interface within a specified
OSPF area and with the loopback interfaces specified by the IP
addresses as endpoints. cost number configures the OSPF cost for
sending an IP packet on the PE-2 sham-link interface.