NETWORK MANAGEMENT

Network Management

Network Management

Introduction

A bad network is something no one wants to deal with, but at some point every IT professional is handed one and told to turn it around as soon as possible. This unhappy burden may have come in the form of a sudden promotion or a new employer. (Farr, 2008, pp 140 - 142)Or perhaps your company has spent a lot of money acquiring a competitor with a problematic network. Regardless of where it came from, somebody else's mess of a network is now your problem. You have to heal uptime poor performance behind and sloppy security, all on a budget - in the case of an acquisition - without leaving your refined old network to collapse after. (Penttinen, 1999, 89 - 940).

Discussion

Kudos to IT giants such as Cisco, Juniper and Microsoft. Despite some horrible network designs out in the field their equipment continues to work. In many cases, so well that the designer isn't aware of the abomination that is the network architecture. Here are our top 4 picks for network designs that can make your eyes water.

1. Dodgy Net - This design consists of many IP subnets all residing on one single VLAN. For the uninitiated the general rule is 1 IP subnet per VLAN. This helps to segment layer 2 and layer 3 traffic consistently across the network.

Technically, however, it is possible to run all IP subnets on a single VLAN. Of course, you get the worst of both worlds with this approach. IP broadcasts are encapsulated by layer 2 frames that have no boundaries and are in turn seen by every IP device on the network. Those devices outside the IP subnet of the originating host promptly discard the packet but by that stage both performance and security have been compromised.

Correction net impaired designs require a lot of planning and management, because each port access VLAN and port trunk must be identified, labeled and configured.

Configuring Dodgy Net is akin to slipping on a warm sweater in winter then jumping into a cold pool. It just doesn't make sense.

2. Static City - Most network engineers first learn about routing using static routes. Learning to propagate routes via routing protocols comes later but for some lost souls the penny never drops and their network designs inevitably become static cities.

Consider that modern networks can host thousands of subnets and hundred/thousands of routing devices. Now imagine having to write each subnet in the context of each device and manually recount what direction to send the packet. That is a lot of work and it becomes an administrative nightmare in large networks where changes occur on a daily basis.

Here is a simple example of how the workload involved in adding manual routes can grow exponentially. A network with 800 subnets hosted on 50 devices requires 40,000 static entries. Of course, this doesn't take into account summarization but even if you can reduce that number to just 10% of original entries that is still 4,000 routes to manage and ...