Brief description of OSPF packets (1)

OSPFUse5Different packet types. Each type is used to support different, dedicated network functions. This5Type:

· HELLOPackets(Type1).
·Database description message(Type2).
·Link-Status Request Message(Type3).
·Link-Status update message(Type4).
·Link-Status Response Message(Type5).
This5Message types are sometimes indicated by serial numbers rather than names. So,OSPFType5Packets actually refer to links.-Status Response Message. Use all these message typesOSPFHeader.

I,HELLOPackets

OSPFContains a protocol used to establish and maintain the relationship between adjacent sites(HELLOProtocol). These links are called connectivity. Connectivity isOSPFThe basis for exchanging route data.
Through this protocol and the packet type,OSPFNodes can find other nodes in the zone.OSPFNode. Its name indicates its meaning,HELLOThe Protocol establishes communication between possible adjacent routers.HELLOThe protocol uses a special sub-packet structure, which is attached to the standard2 4ByteOSPFHeader. These structures work togetherHELLOPackets.
OSPFAll routers in the network must comply with certain rules, which must be consistent throughout the network. These rules include:
Network mask.
HELLOThe interval between message broadcasts.
 The time when other routers in the network think that an unresponsive router is a dead Node(Router dead Interval).
OSPFAll routers in must use the same value for these parameters, otherwise the network may not work normally. These parameters are passedHELLOPackets are exchanged. They form the basis for communication between adjacent nodes. They must ensure that there is no adjacent relationship between vrouters of different networks.(Connectivity)And all the members of the network need to reach a consensus on how often they connect to each other.
HELLOThe packet also includes a list of other routers that have recently been connected to it.(Use their own vroutersI D). ThisN e I g h B o r (Adjacent person)Domain makes the neighbor discovery process possible.HELLOThe message also includes several other domains, suchDesignated Router (Vro),Backup Designated Router (Back up a specified vro)And other domains. These domains support the maintenance of connectivityOSPFThe stable cycle and convergence of the network are both useful.

II,DDPackets

WhenOSPFThe description of the database to be exchanged when the two routers initialize the connection in(DD)Packets. This message type is used for description rather than for actual transmission.OSPFRouter Link-Status database content. Because the database content may be quite long, multiple database description reports may be required to describe the entire database. In fact, a domain is reserved to identify the database description packet sequence. The receiver sorts the packets so that they can copy the database description packets.
DDExchange Process by inquiry/In this process, a vro acts as the primary router. The other vro acts as the slave router, and the master router sends its route table content to the slave router. Obviously, the relationship between the master and slave is causedDDThe exchange is different. All vrouters in the network work at different time points. In this process, they may be both master and slave.

3. Links-Status Request Message

OSPFThe third type of message is Link.-Status Request message. This packet is used to request the link of the adjacent router.-Status database. On the surfaceDAfter the message is updated,OSPFThe router can find that the adjacent information is neither updated nor completely updated. In this case, the router sends one or several links-Status Request message to its neighbor(Vro with update information)To get more link status information.
The request information must be very specific. It must use the following standard specification to specify the required data:
·Link-Status(L s)Type Number(1To5).
· LSId.
·Advertise a vro.
These specifications indicate a specificOSPFDatabase subset, rather than an example of it. An example is a subset of the same information. This subset has a temporary boundary.(The timestamp.). Remember,OSPFIs a dynamic routing protocol that automatically responds to changes in the Link Status in the network. Therefore,L SThe request recipient interprets the specific route information as the latest data.