The Secrets of Tracing a Route with Traceroute

Introduction In today’s digitally interconnected world, understanding how data travels across the internet is vital. This article delves into the fascinating realm of tracing a route, specifically focusing on the intriguing tool known as Traceroute. Whether you’re a curious internet user or a network administrator, knowing how to decipher the path data takes from your … Read more

Point to point connection with mismatched mask

It is a general practice to assign a /30 IP address to point to point connections. But what will happen if we don’t have same subnet mask at both the ends. As demonstrated in diagram, 2 routers are connected via point to point connection. from router R1 and here are the results: R1#ping … Read more

OSPF without Area 0: Understanding OSPF Routing in Multi-Area Networks

Introduction OSPF is a hierarchical routing protocol. Hence everything between different areas should pass through area 0. Areas are defined as logical grouping of ospf router’s interface in a single routing domain. Area 0 is considered to be the backbone area and two different areas(e.g 1 and 2) will exchange routes only if they are connected by … Read more

Can you fragment the IP Packet more than once?

Introduction I was sitting and doing my work and suddenly a question crossed my mind, “Can you fragment a IP packet more than once?” I don’t know what triggered it but it just came through. I thought and said to myself, Why not? All my fundamentals said, yes it should be able to do it … Read more

Q-in-Q(QinQ) Tunnel Configuration: Enhancing VLAN Scalability and Network Flexibility

With introduction of layer 2 ethernet backbones, customers can connect their different sites at layer 2 level. What should service providers do to transport the customer’s vlans and send it across their layer 2 backbone to the other site. There is a conventional solution of not doing any special config and sending everything on their … Read more

Classless behavior of Classful Routing protocol

Most of the books say that Classful routing protocol does not support classless subnets which is not 100% true, as they can send/receive some subnets even without its Mask. I am taking an example of RIPv1. This is a well-known fact that RIPv1 is a classful routing protocol hence MASK information does not travel with … Read more

IPv4 Packet or IP Packet Format: Understanding the Anatomy of IPv4 Data Transmission

It is very important to understand the structure of an IP packet especially if you are indulged in a lot of IP network troubleshooting. Today most of the networks has been built on IP and IPv4 is the most common IP addressing scheme used. IP addressing can be quite difficult with subnetting and supernetting coming … Read more

Exploring Different Flavors of ARP: Address Resolution Protocol Variants and Extensions

There are a number of flavors of ARP. I don’t know why we came up with different names but fundamentally their working are not very different in different scenarios. Its only the Media and technology which changes and calls ARP with different names: ARP(Address Resolution Protocol): The protocol used to determine MAC address using Network … Read more

Address Resolution Protocol(ARP): A Way to Know Each Other

If we see computer networks from a high level, it is clear that IP(in IP world) is responsible for carrying traffic from one network to another network. This is a separate topic of study, is called Routing in Cisco’s world. Routing defines how the traffic will flow in the network? what path will be taken? How the … Read more

Configuring OSPF Authentication: A Step-by-Step Guide with Sample Configuration

As we all know, security is a big factor in today’s network. We can make our network a bit more secured by enabling ospf authentication. OSPF authenticated routers will allow incoming connections only from the router which are having the same key configured. We can configure ospf authentication in 2 ways: Simple and md5. Simple … Read more