Networking
CCNA tutorials, Cisco guides, and enterprise networking insights for IT professionals.
What is Protocol Dependent Module (PDM)
EIGRP uses a protocol-dependent module (PDM) for routing with several different protocols including IPv4 and IPv6. EIGRP also used PDMs to route Novell’s IPX and Apple Computer’s AppleTalk network-layer protocols. The protocol-dependent module (PDM) is also responsible for carrying information from the routing table to the topology table. protocol-dependent module (PDM) is also responsible for...
Introduction to EIGRP – Exclusive
Enhanced Interior Gateway Routing Protocol (EIGRP) was introduced as a distance-vector routing protocol in 1992. It was originally designed to work as a Cisco proprietary protocol on Cisco devices only. In 2013, Enhanced Interior Gateway Routing Protocol became a multi-vendor routing protocol. Enhanced Interior Gateway Routing Protocol is an advanced version of IGRP that lets...
How to Verify Multiarea OSPF
The majority of the command for multiarea OSPF verification is the same as the command we already used in the verification of single area OSPF. The command, “show ip ospf neighbor”, “show ip ospf” and show ip ospf interface are the same command. The following command specifically includes the information of multiarea OSPF. show ip...
Interarea Route Summarization – Exclusive Explanation
Interarea route summarization in the OSPF must be manually configured on ABRs because OSPF does not support auto-summarization. We can perform internal routes summarization only on ABRs. When route summarization is configured on ABRs, a single type 3 LSA (summary LSA) describing the summary route are forwarded to the backbone area. Multiple routes inside the...
OSPF Route Summarization – Exclusive
Route summarization helps convert multiple routes into a single route, which reduces routing tables. After converting a large routing table into a small routing table, it is propagated into the backbone area. We have already discussed the type of LSAs in the previous article. The LSA types 1 and 2 are generated inside each area,...
How to Configure Multiarea OSPF
OSPF can be implemented as single-area OSPF or multiarea OSPF. The basic steps for a single area or multiarea OSPF implementation are the following:- Gather the network requirements and parameters – The first step for implementing multiarea OSPF is the collecting network requirement and important parameters. The requirement includes the number of hosts and required...
OSPF LSA Types – Exclusive Explanation
OSPF is a link-state routing protocol that is used to find the best path between the source and the destination. The SPF algorithm is used to determine the best path. OSPF enabled routers exchange LSAs to update and maintain LSDBs. LSAs act as database records and provide specific OSPF network details. Currently, 11 different types...
Types of Routers in OSPF – Exclusive
OSPF uses four different types of routers with a unique role and set of defining characteristics within the hierarchy. The routers control the traffic that goes in and out of areas. The OSPF routers are categorized based on the function they perform in the routing domain. The four types of routers are following:- Internal router–...
How to OSPF MD5 Authentication
OSPF supports routing protocol authentication using MD5 Authentication. It is more secure than plain text authentication. It uses the MD5 algorithm to calculate a hash value from the contents of the OSPF packet and a password and then the hash value is transmitted in the packet. The receiver side, which knows the password, calculates its...
Introduction to OSPF Authentication
An attacker with a laptop and a copy of Wireshark can inject false LSAs into an OSPF domain in under 30 seconds if the network uses null authentication. This is not a theoretical attack. A 2024 SANS survey found that 38% of enterprise OSPF deployments still run with no authentication configured, despite RFC 5709 and...