High Speed LANs

Faster nets ... why?

Traffic Patterns: Cisco's 80/20 Rule

Virtually all of Cisco's documents discuss a rapid change in traffic patterns for many local networks. Previously most of the traffic remained local, however now Cisco claims that this has changed and now typically only 20% remains local and the remainder goes elsewhere. Many areas on campus still have in-house servers and the bulk of their traffic remains local. Discussions about traffic flows usually give rise to considerations of ...

Congestion, Utilization/Capacity

One of the reasons often provided for wanting to implement higher speed networking is a perception that it will take care of all the congestion and make everything go faster. Not necessarily so!! One of the most important things you can do when planning network upgrades is to determine just where your traffic is flowing.

There are a myriad of monitoring packages that can help you gauge the utilization of your various segments and to determine if there is congestion. Some of these are:

o Use EtherPeek, Lanalyzer, etc., to view statistics
o Networking has Sniffers that monitor traffic
o View the data from Ethermeters on your subnet via Meterware Reports
o View router stats via Meterware Reports
o Check stats from various interfaces to view dropped packets, re-sends, defers, errors, etc.
o Many devices now collect statistics: accessible via Telnet and SNMP/RMON

Note that some of these are not available for Fast Ethernet, e.g., we currently have only 10 Mbps Sniffers.

Shared vs. Switched

This will be discussed in more detail a little later ... in shared environments every node hears every conversation between devices; switches bracket off private conversations while allowing the packets meant for everyone to be distributed accordingly. This is mentioned in this "Why?" section only to raise an important question: which is more helpful ... having switched 10 or shared 100?

New Features/Price Reduction

A very good reason for considering alternatives to shared 10 equipment is that new integrated circuits have come out that have allowed manufacturers to make switched 10 and switched 10/100 much more economically and with more sophistocated features.

It's Inevitable: Needed or Not!

The faster technologies eventually will become the standard. And there's a corollary...

Politics of New Technologies

THEY have Fast Ethernet, so WE should too!