CCIE study notes : OSPF on-demand circuit backup
CCIE study notes three: OSPF on-demand circuit backup
This difficulty is mainly caused by the interesting regional connectivity of ospf. The key to controlling the backup interface is the ospf area where the backup interface is located.
The Ospf on-demand circuit masquerades the hello packet (on the multicast address 224.0.0.5) to initiate the on-demand circuit. It attempts to control the transmission of the LSA by exchanging LSA information only when the circuit is first activated and setting the DONOTAGE bit of the LSA. If the dial-up link is in AREA0, or if the OSPF network has an external LSA or a Type 5 LSA, or if the OSPF network contains a Type 7 LSA in its NSSA area, the on-demand circuit will not function properly. LSAs of type 5 and 7 or LSAs of NSSA will force a DDR link (such as ISDN) to keep making calls. Most networks will have some form of redistribution operation, and there will be a type 5 LSA constantly oscillating in the network.
Only the STUB area connected to the on-demand circuit can avoid the DDR link non-stop call caused by the type 5 LSA. To configure an on-demand circuit, you need to perform the following three steps: 1 Configure the interface as an OSPF peer-to-peer network interface at both ends of the network link. A hello packet cannot be suppressed in a "broadcast" type network, and a virtual link cannot be established in a stub area.
2 Configure all interfaces to the same STUB area with the AREA X STUB command.
3 Configure the caller of the network link as an on-demand circuit with the interface command ip ospf demand-circuit.
Note: The backup interface will only enter AREA 0 when the primary interface is in AREA 0. Use the backup interface command or the dialer watch command to start dynamic routing. Remember that all LSAs will enter AREA 0. The continuous flow of LSAs into AREA0 will result in non-stop calls to the interface. In this case, some configuration techniques must be run to force the interface to not make unnecessary calls.
CCIE study notes four: OSPF virtual link for ccie security experience
When changing the value of any timer in AREA0 or making OSPF authentication mode, be sure to remember to modify it at the other end of the virtual link.
Use the show ip ospf virtual-links command with the standard show ip route and ping to verify the functionality of the virtual link. If it works normally, the status of the virtual link should be "UP". The status of the adjacency is "FULL". To mark a route as the default route without using a static route, use the global command default-network „„.
The propagation is then implemented by the OSPF command default-information originate always. One thing to keep in mind here is that a router needs to forward packets to a one-hop default route. All routers need to enable the global command ip classless. The default route does not automatically enter the NSSA area. Therefore, the NSSA area must add the parameter default-information-originate to the router command area 10 nssa.
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This difficulty is mainly caused by the interesting regional connectivity of ospf. The key to controlling the backup interface is the ospf area where the backup interface is located.
The Ospf on-demand circuit masquerades the hello packet (on the multicast address 224.0.0.5) to initiate the on-demand circuit. It attempts to control the transmission of the LSA by exchanging LSA information only when the circuit is first activated and setting the DONOTAGE bit of the LSA. If the dial-up link is in AREA0, or if the OSPF network has an external LSA or a Type 5 LSA, or if the OSPF network contains a Type 7 LSA in its NSSA area, the on-demand circuit will not function properly. LSAs of type 5 and 7 or LSAs of NSSA will force a DDR link (such as ISDN) to keep making calls. Most networks will have some form of redistribution operation, and there will be a type 5 LSA constantly oscillating in the network.
Only the STUB area connected to the on-demand circuit can avoid the DDR link non-stop call caused by the type 5 LSA. To configure an on-demand circuit, you need to perform the following three steps: 1 Configure the interface as an OSPF peer-to-peer network interface at both ends of the network link. A hello packet cannot be suppressed in a "broadcast" type network, and a virtual link cannot be established in a stub area.
2 Configure all interfaces to the same STUB area with the AREA X STUB command.
3 Configure the caller of the network link as an on-demand circuit with the interface command ip ospf demand-circuit.
Note: The backup interface will only enter AREA 0 when the primary interface is in AREA 0. Use the backup interface command or the dialer watch command to start dynamic routing. Remember that all LSAs will enter AREA 0. The continuous flow of LSAs into AREA0 will result in non-stop calls to the interface. In this case, some configuration techniques must be run to force the interface to not make unnecessary calls.
CCIE study notes four: OSPF virtual link for ccie security experience
When changing the value of any timer in AREA0 or making OSPF authentication mode, be sure to remember to modify it at the other end of the virtual link.
Use the show ip ospf virtual-links command with the standard show ip route and ping to verify the functionality of the virtual link. If it works normally, the status of the virtual link should be "UP". The status of the adjacency is "FULL". To mark a route as the default route without using a static route, use the global command default-network „„.
The propagation is then implemented by the OSPF command default-information originate always. One thing to keep in mind here is that a router needs to forward packets to a one-hop default route. All routers need to enable the global command ip classless. The default route does not automatically enter the NSSA area. Therefore, the NSSA area must add the parameter default-information-originate to the router command area 10 nssa.
CCIE RS is most popular cisco certification, but you can try other track such as: ccie security 400-251 dumps that you need not to pass ccnp security 300-210 exam dump. good luck for all.
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