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What are the 7 states of OSPF?

What are the 7 states of OSPF?

The states are Down, Attempt, Init, 2-Way, Exstart, Exchange, Loading, and Full.

What are the four 4 types of OSPF routers?

Four Types of OSPF Routers

  • Routers for internal use: Internal routers. Internal routers are routers that belong to the same OSPF region as their directly connected networks.
  • Area Borders Routers.
  • Autonomous Systems Boundary Routers.
  • Backbone Routers.

How OSPF works step by step?

How does OSPF work?

  1. There are three steps that can explain the working of OSPF:
  2. Step 1: The first step is to become OSPF neighbors.
  3. Step 2: The second step is to exchange database information.
  4. Step 3: The third step is to choose the best route.

What is 2 way state in OSPF?

OSPF devices will be in the Full state only with the DR and BDR. OSPF devices will be in the 2 Way state if the neighbor is neither a DR nor BDR; this is expected behavior, as per the RFC for broadcast networks.

What are the 5 types of OSPF packets?

Packet types for OSPF

  • Hello packet. This packet is sent by the OMPROUTED server to discover OSPF neighbor routers and to establish bidirectional communications with them.
  • Database description packet.
  • Link-state update packet.
  • Link-state request packet.
  • Link-state acknowledgment packet.

Why OSPF is called link-state?

The OSPF protocol is a link-state routing protocol, which means that the routers exchange topology information with their nearest neighbors. The topology information is flooded throughout the AS, so that every router within the AS has a complete picture of the topology of the AS.

What is E1 and E2 in OSPF?

E1 routes indicate cumulative cost to reach the destination i.e. int indicates cost to reach ASBR + cost to destination from ASBR. E2 route reflects cost only from the ASBR to destination. This is the default used by ospf for redistribution.

What is LSA in OSPF?

Link State Advertisements (LSAs) are messages communicated via multicast to other routers in the OSPF domain. They are sent from internal routers to the DR/BDR routers to announce changes. This communication occurs on multicast address 224.0. 0.6.

What are the LSA types in OSPF?

OSPF LSA Types Explained

  • LSA Type 1: Router LSA.
  • LSA Type 2: Network LSA.
  • LSA Type 3: Summary LSA.
  • LSA Type 4: Summary ASBR LSA.
  • LSA Type 5: Autonomous system external LSA.
  • LSA Type 6: Multicast OSPF LSA.
  • LSA Type 7: Not-so-stubby area LSA.
  • LSA Type 8: External attribute LSA for BGP.

Why BGP is used over OSPF?

Scale: BGP is more flexible and scalable than OSPF and it is also used on a larger network. Preferred path: OSPF is used to determine the fastest route while BGP puts emphasis on determining the best path. Protocol: In OSPF, internet protocol is used. While in BGP, transmission control protocol is used.

What is N1 and N2 in OSPF?

E1 or E2 or N1 or N2 type routes are based upon cost of the route. E2 or N2 routes tell OSPF routers to set the metric as the metric at the point of redistribution.(At the ASBR) E1 or N1 routes tell OSPF routers to add the internal costs to reach the ASBR to the cost set at the point of redistrbution (At the ASBR)

What is LSP and LSA?

What is an LSA and LSP? An LSA is a Learning Support Assistant and an LSP is Learning Support Practitioner. This is somebody who supports learning in the classroom. Sometimes they will support individual children, at other times they may work with a group or with the whole class.

What port is RIP?


Routing Information Protocol (RIP) is a dynamic routing protocol that uses hop count as a routing metric to find the best path between the source and the destination network. It is a distance-vector routing protocol that has an AD value of 120 and works on the Network layer of the OSI model. RIP uses port number 520.


OSPF routers communicate using IP packets. OSPF messages ride directly inside of IP packets as IP protocol number 89. Because OSPF does not use UDP or TCP, the OSPF protocol is fairly elaborate and must reproduce many of the features of a transport protocol to move OSPF messages between routers.

What is E1 E2 and N1/N2 routes in OSPF?

E1 or E2 or N1 or N2 type routes are based upon cost of the route. Consider this example. ASBR,R1 R2 R3 are connected in line via Ethernet interface with cost of 10 each. Hope that helps!

Does OSPF uses TCP or UDP?

OSPF Packets
Because OSPF does not use UDP or TCP, the OSPF protocol is fairly elaborate and must reproduce many of the features of a transport protocol to move OSPF messages between routers. There can be one of five OSPF packet types inside the IP packet, all of which share a common OSPF header.

Does RIP use UDP or TCP?

RIP uses User Datagram Protocol (UDP) port 520. RIP has the following architectural limitations: The longest network path cannot exceed 15 hops (assuming that each network, or hop, has a cost of 1).

What is Area 0 called in OSPF?

Backbone Area
Backbone Area This is the central area in your OSPF routing domain which all areas must connect to. This area is labeled area 0 (or the longhand version 0.0. 0.0). When traffic needs to pass from one area to another, it must traverse the backbone.

What is difference between E1 and E2 in OSPF?

What is Type 1 and Type 2 in OSPF?

A type 1 route has a metric that is the sum of the internal OSPF cost and the external redistributed cost. A type 2 route has a metric equal only to the redistributed cost, as shown in Figure 14-2.

Why RIP is Layer 7 protocol?

RIP is responsible for announcing changes in routes between routers. Layer 7 is the application layer, which is what the user touches. Layer 3 is the network layer where routing and IP both reside. RIP is not a userland process; users do not interact with it, and user-level applications do not interact with it.

What is BGP port number?

BGP peers are established by manual configuration between routing devices to create a TCP session on port 179.

How many LSA are in OSPF?

6 Types of OSPF LSA.

What OSI layer is BGP?

BGP in networking is based on TCP/IP. It operates on the OSI Transport Layer (Layer 4) to control the Network Layer (Layer 3).

What OSI layer is OSPF?

4 Transport
The OSI Seven Layer Model

Level Name Examples
1 Physical DSL, Ethernet, ISDN, RS-232
2 Data Link Ethernet, PPP, SLIP, HDLC
3 Network IP, IPX, DDP
4 Transport TCP, UDP, OSPF, BGP