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OSPF Virtual Link Downloads OSPF Virtual Link Document ID: 47866 Contents Introduction Prerequisites Requirements Components Used Conventions Configure Network Diagram Configurations How the Virtual Link Operates Calculate the Shortest Path Using a GRE Tunnel Instead of a Virtual Link Verify Examine the OSPF Database Troubleshoot Troubleshoot Commands NetPro Discussion Forums - Featured Conversations Related Information Introduction All areas in an Open Shortest Path First (OSPF) autonomous system must be physically connected to the backbone area (Area 0). In some cases, where this is not possible, you can use a virtual link to connect to the backbone through a non-backbone area. You can also use virtual links to connect two parts of a parti...

Configuring EIGRP Stub Routing To configure a remote or spoke router for EIGRP stub routing, use the following commands beginning in router configuration mode: Command Purpose Step 1 router(config)# router eigrp as-number Configures a remote or distribution router to run an EIGRP process. Step 2 router(config-router)# network network-number Specifies the network address of the EIGRP distribution router. Step 3 router(config-router)# eigrp stub [ receive-only | connected | static | summary ] Configures a remote router as an EIGRP stub router. Verifying EIGRP Stub Routing To verify that a remote router has been configured as a stub router with the EIGRP Stub Routing feature, use the show ip eigrp neighbor detail command from the distribution router in privileged EXEC mode. The last line of the output will show the stub status of the remote or spoke router. The following example output is from the show ip...

Configuring EIGRP Stub Routing To configure a remote or spoke router for EIGRP stub routing, use the following commands beginning in router configuration mode: Command Purpose Step 1 router(config)# router eigrp as-number Configures a remote or distribution router to run an EIGRP process. Step 2 router(config-router)# network network-number Specifies the network address of the EIGRP distribution router. Step 3 router(config-router)# eigrp stub [ receive-only | connected | static | summary ] Configures a remote router as an EIGRP stub router. Verifying EIGRP Stub Routing To verify that a remote router has been configured as a stub router with the EIGRP Stub Routing feature, use the show ip eigrp neighbor detail command from the distribution router in privileged EXEC mode. The last line of the output will show the stub status of the remote or spoke router. The following example output is from the show ip...

Here is a simple tip to write an access-list for even or odd networks. Lets say we are asked to permit all odd or permit all even for 192.168.1.0/24 ? We’ll play the game with last octet or I should say the least significant bit of last octet. -If it is 0, the IP address will be Even -If it is 1, the IP address will be Odd 192.168.1.00000001 = 192.168.1.1 - odd 192.168.1.00000011 = 192.168.1.3 - odd 192.168.1.00000010 = 192.168.1.2 even 192.168.1.00000100 = 192.168.1.4 even FOR Even Networks The IP address will be 192.168.1.0 With the wild card mask as 0.0.0.254 254 = 11111110 Here, 0 means DO CARE of the last bit in IP address (must be ZERO) Hence ACL will be access-list 1 permit 192.168.1. 0 0.0.0. 254 For Odd Networks The IP address will be 192.168.1.1 With the wild card mask as 0.0.0.254 254 = 11111110 Here, 0 means DO CARE of the last bit in IP address (must be ONE) Hence ACL will be access-list 1 permit 192.168.1. 1 0.0.0. 254