What is an OSPF LSA?
The link-state advertisement (LSA) is a basic communication means of the OSPF routing protocol for the Internet Protocol (IP). It communicates the router’s local routing topology to all other local routers in the same OSPF area.
What is Type 4 LSA OSPF?
OSPF Type 4 ASBR Summary LSA
A type 4 LSA identifies the ASBR and provides a route to the ASBR. The link-state ID is set to the ASBR router ID. All traffic that is destined to an external autonomous system requires routing table knowledge of the ASBR that originated the external routes.
What is Type 5 LSA OSPF?
An OSPF type 5 LSA is originated by an Autonomous System Boundary Router (ASBR) and flooded within the OSPF area. These routes are generated by means of redistribution into OSPF from other protocols or by the redistribution of connected or static routes.
What is Type 3 LSA OSPF?
The Summary (Type 3) LSA is used for advertising prefixes learned from the Type 1 and Type 2 LSAs into a different area. The Area Border Router (ABR) is the OSPF device that separates areas and it is this device that advertises the Type 3 LSA.
What is Type 7 LSA OSPF?
What Is a Type 7 LSA? This is a type 7 LSA that is generated by an NSSA ASBR. Type 5 LSAs are not allowed in NSSA areas, so the NSSA ASBR generates a type 7 LSA instead, which remains within the NSSA. This type 7 LSA gets translated back into a type 5 by the NSSA ABR.
How many OSPF LSA types?
6 Types of OSPF LSA.
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.
What is the difference between LSA 5 and LSA 7?
The difference between Type-5 LSA and Type-7 LSA is that Type-7 LSA can live only into NSSA area, so it will never leave the NSSA area. Instead Type-5 LSA can be propagated to the other areas (backbone and non-backbone). – Both of them are generated by the ASBR.
What is Type 6 LSA OSPF?
LSA Type 6 – OSPF Group Membership LSA
LSA Type 6 (Group Membership LSA) packets were designed for Multicast OSPF (MOSPF), a protocol that supports multicast routing through OSPF. MOSPF is not supported by Cisco and is not widely used and is expected to be retired soon.
What are the 7 stages of OSPF?
The states are Down, Attempt, Init, 2-Way, Exstart, Exchange, Loading, and Full.
What are OSPF LSA types?
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 is type 4 LSA required?
Type 4 LSA is generated by the ABR. Link ID in that is the router ID of ASBR and Adv. Router is the ASBR itself. LSA 4 is required to tell the routers in other areas how to reach the ASBR to get to external network eventually.
What is the difference between OSPF LSA type 4 and 5?
In short, LSA type 4 tell what nodes are ASBR in an OSPF domain and provide routing information (path cost) to reach them using the OSPF inter-area methods. An LSA type 5 is originated by an ASBR node and contain an IP prefix that is injected into the OSPF domain.