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Tag Archives: ccie
Frame-relay: Inverse ARP
Frame relay is a packet switching technology that emulates like a switch. Switch uses ARP broadcast to find out the mac address of the host so that switch can forward the frame to the destined switch port. Frame relay however … Continue reading
Spanning Tree Protocol (802.1D)
This protocol prevents bridging loop created by redundant links within switch network. STP calculation will make switch/es block its own port so that the switch path is one straight line and not a loop. This is perhaps the most confusing … Continue reading
Posted in High Availability, Switch
Tagged 802.1D, bridge id, bridge priority, ccie, ccna, ccnp, Cisco switch, lowest bridge ID, port priority, portfast, root port, spanning tree protocol, STP, STP port cost, what are STP port roles, what is root port, what is Spanning Tree Protocol, what is STP, what is STP port states
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On demand routing (ODR)
1. Must turn on CDP for all routers; hence this routing protocol is Cisco proprietary. 2. Only works in hub and spoke topology. 3. Has a default administrative distance of 160. 4. Extremely easy to configure. 5. Makes default route … Continue reading
Posted in Route
Tagged ccie, ccnp route, cdp, cisco discovery protocol, odr, on demand routing
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Type 10 LSA – Opaque LSA
This LSA is an extension of OSPF. The extension is for doing OSPF traffic engineering. MAX-LSA – Protects against adjacent router’s excessive LSA in the OSPF domain. Excessive LSA will cost router’s high cpu resources. This is to limit the … Continue reading
Posted in OSPF, Route
Tagged ccie, ccnp route, link state advertisement type, opaque LSA, ospf, ospf lsa type, type 10 LSA
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LSA types
1. Router LSA – This LSA is produced by every router. The LSA contains information of the router’s connected interfaces, states, neighbour router type, any known ospf routers connected to the router’s link and outgoing cost of each link. This … Continue reading
Posted in OSPF, Route
Tagged ccie, ccnp route, link state advertisement, link state advertisement type, lsa type, ospf, ospf lsa
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Building OSPF adjacency
Database Description Packet (DDP) – This contains the summary of all the LSAs, it only contains the headers and not the complete LSA. This allows router to see if its own link state database is updated. This is type 2 … Continue reading
Posted in OSPF, Route
Tagged building ospf adjacency, ccie, ccnp route, ospf, ospf adjacency, ospf packet type
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OSPF finite state machine
Reference: Routing TCP/IP 2nd Edition Jeff Doyle, page 353-357. OSPF router goes through several states before adjacency is formed. DOWN – No hello packets was seen from the neighbour router since the last dead interval. If an OSPF router goes … Continue reading
Posted in OSPF, Route
Tagged ccie, ccnp route, ospf, ospf finite state machine, ospf state machine, ospfv2
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Understanding OSPF
Open Shortest Path First is using Djikstra’s shortest path first algorithm. It is a link-state routing protocol, another link-state routing protocol is Intermediate System to Intermediate System also known as IS-IS. General facts about OSPF 1. Uses its own transport … Continue reading
