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 …
Category: Link State Routing Protocols
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 …
Network statements in Lazy mode & Deep dive into OSPF Network command
During my journey of CCIE, I noticed an OSPF feature worth of sharing. In Core/IGP routing, instead of typing a lot in network commands in OSPF, we can just use network 0.0.0.0 255.255.255.255 and more surprisingly 0.0.0.0 0.0.0.0. Once you enter all zeroes, running-config will convert it to quad 0 followed by quad 255. We can also use 0.0.0.0 0.0.0.0. It just includes all interfaces the same way as if you do 0.0.0.0 255.255.255.255. Below is the practical demonstration: If the router has all interfaces in a single area, I always use network 0.0.0.0 255.255.255.255 area area-id. Since, Read More …
OSPF Timers (OSPF Intervals)
Routing protocol use Timers (Intervals) to keep all routers in a domain updated. Through the use of these timers, a routing protocol is able to maintain a stable neighbor relationship and ensure routes are propagated correctly. OSPF routing devices constantly track the status of their neighbors by sending and receiving Hello Packets to confirm whether each neighbor still is functioning normally. We can use these OSPF Intervals (OSPF Timers) to adjust the network convergence time in an OSPF network. Types of OSPF Timers: OSPF uses two types of OSPF Intervals (Timers): Tells the router after how long should it Read More …
Open Shortest Path First (OSPF)
Introduction OSPF is an open source Routing protocol that handles routing for IP traffic standardized in IETF RFC2328. OSPF is classified as an Interior Gateway Protocol (IGP). This means that it distributes routing information between routers belonging to a single Autonomous System. The OSPF protocol is based on link-state or SPF technology. It was designed mainly for the TCP/IP internet environment. Main focus was to produce a protocol that responds quickly to topology changes, with small amounts of control traffic. OSPF is a dynamic routing protocol. It quickly detects topological changes in the AS (such as router interface failures) and Read More …