Shulou(Shulou.com)06/01 Report--

1.LSA 's head.

The LSA header is used at the beginning of all LSA

There are three fields in the LSA header that uniquely identify each LSA: type, link state ID, advertisement router

The other three fields uniquely identify the latest instance of a LSA: aging time, serial number, checksum

Aging time Age

Time experienced after the LSA was issued, in seconds

Optional Option

Type Type

Type of LSA

Link-state ID Link State Id

Some of the OSPF domains described by LSA

Advertise router Advertising Router

Router ID that originates LSA

Serial number Sequence Number

When a new instance of LSA is generated, the serial number increases

Checksum Checksum

Checksum of all information about LSA

Length Length

The length of the LSA including the LSA header, expressed in octet bytes

two。 Router LSA

Router LSA advertises host routes as stub networks. Its link ID field carries the host's IP address, while the link data field carries the mask of the host address 255.255.255.255.

Link-state ID Link State ID

Router ID of the originating router

V, virtual link end point

Set to 1, indicating that the originating router is an endpoint of one or more virtual links with full adjacencies

E, outer part

When the originating router is ASBR, this bit is set to 1

B, boundary bit

Set to 1 when the originating router is ABR

Number of links

The number of router links described by a LSA

Link type Link Type

Link ID Link ID

Link data Link Data

ToS number Number of ToS

List the number of the specified service type metric for this link

Metric Metric

The cost of a link

ToS

The metric and the type of service involved are specified

Cisco only supports ToS=0

ToS metric

Metrics associated with the tos value

3. Network LSA

Link-state ID

Interface IP address of the DR router in the network

Network mask

The mask of the address or subnet used on this network

Connected router

List the router ID of the ID,DR router itself of all routers on the multiaccess network that have a full adjacency with DR

4. Network Summary LSA and ASBR Summary LSA

Network Summary LSA and ASBR Summary LSA have the same format

Link-state ID

For type 3 LSA, the IP address of the network or subnet it advertises

For LSA of type 4, router ID of ASBR

Network mask

Subnet mask or address of the advertised network in the LSA of type 3

In the LSA of type 4, it has no practical meaning and is set to 0.0.0.0

If a type 3 LSA advertises a default router, the link state ID and netmask fields will both be 0.0.0.0

Measurement

The cost of the route to the destination

5. External LSA of autonomous system

Link-state ID

IP address of the destination

Network mask

Subnet mask or address of the advertised destination

If the LSA of type 5 is advertising a default route, both the link state ID and the netmask field are set to 0.0.0.0

E, external metric bit

E-bit is set to 1 and measurement type is E2

E-bit is set to 0 and measurement type is E1

Measurement

The cost of routing, set by the ASBR router

Forwarding address Forwarding Address

The address to which packets arriving at the advertised destination should be forwarded, and if the forwarding address is 0.0.0.0, the packet will be forwarded to ASBR.

External routing flag

6.NSSA external routing LSA

Forwarding address

If the network is advertised as an internal route between a NSSA ASBR router and an adjacent autonomous system, then the forwarding address refers to the next-hop address of the network

If the network is not advertised as an internal route, then the forwarding address will be the route ID of the NSSA ASBR router

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