Redundancy and Loop Avoidance

When designing a switched or bridged network, you’ll almost certainly need to consider redundancy. While network redundancy is a great idea in principle, there are issues that you’ll need to be aware of. The biggest issue is that bridging redundancy exposes networks to a loop, and loops cause major problems if not dealt with properly.

The problems associated with network loops go back to the days when bridging was the primary way of segmenting a LAN. The idea was to have more than one bridge connecting two segments, in order to provide a redundant path should a link or bridge fail. The problem with having this redundancy in a bridged environment is that may create loops, and network loops are capable of causing communication problems. In the case of a bridging loop, a network becomes susceptible to broadcast storms.

In this section you’ll notice that I tend to refer to bridges instead of switches. The main reason is that a bridged network is easier to diagram that one using switches. For all intents and purposes, when describing loops the terms bridge and switch can be used interchangeably.

Author: Dan DiNicolo

Dan DiNicolo is a freelance author, consultant, trainer, and the managing editor of He is the author of the CCNA Study Guide found on this site, as well as many books including the PC Magazine titles Windows XP Security Solutions and Windows Vista Security Solutions. Click here to contact Dan.