Waqas Karim is a seasoned Network Expert … Geek. He is the founder of ATech. ATech was started for learning & sharing. Over time the platform has grown to include other resources which continue to attract fellow networkers.
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His specialty is networking, but his interest & expertise spans from traditional IT to Network Security including Programming, Virtualization, Service Provider & so on... no matter the badge on the box.
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Good, especially the detailed answers to the questions asked
If OSPF neighborship in “down” state then how can i know its cause?
First, we have to make sure that two OSPF devices should be connected back to back with cables connected on correct interfaces. Also, make sure that IP and subnet mask should be correct. Then run the OSPF process, if not running already. Advertise the interface segments on both routers. Hello, Dead timers and MTU size should be same at both ends. There should not be any access-list or transparent firewall blocking the OSPF Packets or IP addresses. Neighbourship should establish now. Area number and authentication parameters must match. If issues are still there, then check the router logs and try… Read more »
Hmmm…..
got it. Many Thanks
Why does’t DR and BDR election happen in OSPF P2P and P2MP Network?
On Point-to-Point type, DR and BDR election does’t happen because it is used when only two routers need to form an adjacency on a pair of interfaces.
In case of Point-to-Multipoint type, it uses a multicast OSPF hello packet to automatically discover the neighbors so DR and BDR elections are not required.
There is any specified IP for dr/bdr?
Yes, OSPF Routers use 224.0.0.5 multicast IP address. However, DR and BDR use 224.0.0.5 and 224.0.0.6. They also use 224.0.0.6 while replying to OSPF routers in Broadcast Multi Access network.
What is OSPF Router ID and how is it elected?
Router ID is similar to IP address which is also 32-bit. It is elected as highest IP Address of active physical interfaces if loopback is not present. It can also be set manually but it will take effect when OSPF process is reset completely or device is reloaded. There should be only one router ID per device running OSPF to avoid database issues.
Thanks, these posts really are great. Revising for ICND2.
Its nice