Cisco Embedded Event Manager (EEM) is a scripting and automation mechanism within the IOS that triggers specific actions in response to network events. It is a flexible and robust tool which can provide scalable solution to given scenarios. It is composed with 2 pieces: -Applets which a collection of CLI commands -Scripting which are defined using [ Read More ]
NTP is a protocol designed to basically time synchronize network devices across Local or Wide Area Networks. You would probably guess how critical this is in terms of troubleshooting as it would greatly assist in pinpointing time events and help isolate the root cause of a problem. On top of that, certain network devices need [ Read More ]
IS-IS is a Link State IGP that’s fairly similar to OSPF in terms of operations. In fact, they were created around the same time ! IS-IS stands for Intermediate System to Intermediate System. In essence, an “Intermediate Systems” simply means a “Router”. So, “Router to Router” is a fair analogy when describing the protocol. Typically IS-IS is [ Read More ]
Redistribution is basically the injection of routes learned from one routing domain, static routes or directly connected routes to another routing domain. The reason for redistribution is to have end to end connectivity between routing domains which then could serve different purposes such as backup path to a specific destination for instance. Redistribution can be [ Read More ]
It’s already no secret that organizations differ in terms of governance policies and regulations. An organization may need to route 3rd party vendor traffic for instance via a T1 to reach specific destinations as opposed to a default path. PBR provides us with the ability to implement packet forwarding and routing via a specific next [ Read More ]
Have you heard of something called “The Internet” ? Well, BGP is actually the routing protocol that makes it all happen ! I would like to start off by saying BGP is by far my FAVORITE routing protocol ! By Far !!! Did I say by far ?! Not even close to the other ones [ Read More ]
OSPF is a routing protocol providing dynamic adjacency capabilities. It is a Link State protocol and is mostly used as IGP in large entreprise networks. Another Link State protocol is IS-IS which is still used in certain circumstances such as on the MPLS core of a Service Provider network… Also, the underline protocol running “TRILL” [ Read More ]
RIP is a distance vector routing protocol that uses hop counts as its metric to undergo a best path selection process. It can be considered somewhat effective for small networks but problematic for larger network as it transmits its entire routing table to its peers every 30sec. We will leverage the following topology to demonstrate how [ Read More ]
EIGRP named mode has been around for years. It is a bit different from the classic EIGRP that most Engineers are used to but it gives you more control and an edge in terms of troubleshooting as all the configuration are centric basically. At this point, if you are unfamiliar with EIGRP, I would suggest [ Read More ]
EIGRP stands for Enhanced Interior Gateway Routing Protocol which is just like the name implies, an enhanced version of the legacy IGRP. It is considered as an “Advanced Distance Vector Protocol” which uses 5 different type of packets to exchange information: -Hello: Hello packets are used to discover EIGRP neighbors. -Update: Updates are mainly used for [ Read More ]