OSPFv2 LSA Tipleri

Detaylı açıklaması ve ayrıca genel OSPF sorunlarının incelemesi aşağıdaki Cisco Dokümanında detaylı olarak anlatılmıştır.

Troubleshooting Ospf

Ayrıca aşağıdaki link’de kavramların anlaşılmasında yardımcı olabilir.

http://packetlife.net/blog/2008/jun/24/ospf-area-types/

OSPF network Tipleri :

OSPF Network Types
OSPF Network Types

Type-1 (Router) LSA :

http://wiki.nil.com/Type-1_(Router)_LSA

1 Stub interfaces

2 Point-to-point interfaces

3 Unnumbered point-to-point interfaces

4 Links to transit multi-access interfaces

5 Additional Resources

 

Stub interfaces

A type-3 (stub) link is added to the router LSA for each stub interface belonging to the OSPF process. A stub interface could be a loopback interface or any other point-to-point or multipoint interface on which there are no OSPF neighbors.

Example #1: A router with a single loopback interface generates a type-1 LSA (even though it has no OSPF neighbors) with a single stub link.

Relevant parts of the router configuration

OSPF-enabled interfaces

Contents of the router LSA

Example #2: A router with a loopback interface and a multi-access (LAN) interface with no OSPF neighbors generates a type-1 LSA with two stub links, one describing the loopback interface, the other the LAN interface.

Relevant parts of the router configuration

State of the OSPF interfaces

Router LSA with two stub links

Point-to-point interfaces

Two links are added to the router LSA for each point-to-point interface:

  • A router link describing the connection to the OSPF neighbor
  • A stub link describing the subnet of the point-to-point interface.
The router interface address field in the router link is the local IP address assigned to the interface.

Example #3: A router with a loopback interface and a point-to-point WAN link generates a type-1 LSA with two stub links (one describing the loopback interface, the other the point-to-point WAN subnet) and a router link (describing the connection to the OSPF neighbor).

Relevant parts of the router configuration

State of the OSPF interfaces

Router LSA describing a point-to-point link and a loopback interface

Unnumbered point-to-point interfaces

A single router link is added to the router LSA for each OSPF neighbor reachable across a point-to-point interface. The router interface address field in therouter link is an internal interface number (not necessary equal to the SNMP index of the local interface as required by RFC 2328).

Example #4: A router with a loopback interface and an unnumbered point-to-point WAN link generates a type-1 LSA with a stub link (describing the loopback interface) and a router link (describing the connection to the OSPF neighbor).

Relevant parts of the router configuration

OSPF interface state

Router LSA has a single router link and a single stub link

The contents of the Router Interface address field in the router link in the router LSA do not necessarily match the SNMP interface index (displayed below).

SNMP interface index of the WAN interface

Links to transit multi-access interfaces

Router LSA contains a link to transit network for each transit broadcast or NBMA interface. The transit network referred to in the router LSA is the type-2 LSA originated by the designated router selected on the interface.

transit interface is an interface with at least one OSPF neighbor.
The router advertises a multi-access interface as a stub link as long as it has no OSPF neighbors reachable through the interface. When the adjacency to the first OSPF neighbor reaches the FULL state, the router LSA is changed: the stub link is replaced by a transit link.

Example #5: A router with a loopback interface and a transit Ethernet interface generates a type-1 LSA with a stub link (describing the loopback interface) and link to a transit network (the type-2 LSA originated by the DR).

Relevant parts of the router configuration

The show ip ospf interface command shows a single OSPF neighbor on the Fast Ethernet interface. A1 is the backup DR (the State column in the printout), therefore the other router must be the DR.

OSPF interface state

The router LSA has two links: a stub link and a link to the type-2 LSA originated by the DR.

Router LSA describing a connection to a transit network

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