Similar to LSR, LSU (Link State Update) is the response/reply to LSR. Each Link State Update packet carries a collection of link state advertisements one hop further from its origin. Consider the simple below topology with two Routers: LSU’s are generated in response to the LSR’s. It is obvious from the below detail, spend some time with it to understand it fully:
Tag: DBD
OSPF Type2 Message / DBD Packet (Database Descriptor)
DBD (Database Description or Type2 OSPF Packet) is a sort of summary of the OSPF Database in a router. DBD is used to check if the LSDB between 2 routers is the same. These packets are exchanged when an adjacency is being initialized. They describe the topology information a router has in its database. DBD uses poll-response procedure (master/slave). Master sends DBD packets/polls which are acknowledged by the slave. Consider the simple below topology with two Routers: As soon as we enable OSPF on the router interfaces, it starts exchanging Hello and DBD Packets. It is obvious Read More …
OSPF Type1 Message / Hello Packet
Hello packet, also called Type1 OSPF Packet, is a special packet/message that is sent out periodically from a router to establish and confirm network adjacency relationships. These packets are sent periodically on all interfaces in order to establish and maintain neighbor relationships. Hello Packets contain different parameters including Network mask, Hello Interval and Router Dead Interval,…. These parameters are needed to form neighbor relationships. All routers connected to a common network (NBMA,…) must agree on certain parameters. Below is the detailed description of Hello Packet & its fields: Below is description of fields in the OSPF Hello Packet: Read More …
OSPF Packet Formats
There are different OSPF Packet Types which are used for different purposes. OSPF has five types of Packets. OSPF uses its own protocol and doesn’t use a transport protocol like TCP or UDP. It uses IP Protocol 89. Let us have a detailed look into each type of Packet now. Below is a general view of OSPF Packet. When changing from one type to another in above five categories, just the TYPE & DATA fields are changed. This is how it will look when we deep dive into the packet itself. Below are the five types of Packets in detail Read More …
OSPF Packet Types
There are different OSPF Packet Types which are used for different purposes. We know that OSPF routers need to perform different duties in order to route traffic. e.g. establish and maintain adjacencies, send and receive requests, ensure reliable delivery of Link State advertisements (LSAs) between neighbors and to describe Link State Databases. All these duties are performed using messages/Packets. Only one type of message/packet cannot perform all these duties. So, different types of messages/Packets are needed. OSPF has five types of Packets in total which are listed in below. Each type of packet has its own duties to perform. All these Read More …