Wireshark is the most useful & popular tool for packet Level deep Network Analysis & Troubleshooting. Most importantly, it is open source. It is like a measuring meter or device to find and examine what is going on inside a network cable or port just like a multimeter is used by an electrician to examine what is going on inside an electric cable … but of course at much deeper level. Wireshark or such SW tools are not something very new. Such tools were available in the past as well but they were very expensive and proprietary because they were mostly Read More …
Category: CCNP – Route
OSPF Virtual Links
Virtual Link is a non-Physical connectivity or link. As we know OPSF must be connected with Backbone Area0 but sometime it becomes difficult due to some reasons. So there we required Virtual Links for logical connection to Backbone. Also known as logical link which uses in least cost path connectivity between routers or ABR or backbone/Non-backbone. A virtual link does not have ABR physical Connectivity to Backbone till to configure virtual link between non-backbone area and Backbone. In between two routers, a virtual link can be configured, that have an interface to a single common Transit/Non-backbone area but it can’t Read More …
OSPF Authentication
What is Authentication: Authentication is the mechanism of recognizing the identity of a user. Associating an incoming request with a set of identifying credentials is called Authentication. The credentials provided are compared to those in the database of the authorized user’s information register on a local operating system or somewhere remote. If the user is on white-list then he/she is allowed the access, otherwise the access is rejected simply. Types of OSPF Authentication OSPF supports two types of authentication i.e. Plain Text authentication and Message Digest 5 (MD5) authentication. As a message/packet required authentication for both destinations. 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 …