Chapter 4: Reliable Connectivity

Overview

So, do you think that just because the "circuit" between you and your ISP rarely goes down, you have reliable connectivity? What happens when your border router fails? What happens when your firewall goes down? What happens when routing fails? What happens when all of the above still appear to be operational but your packets don't go anywhere ? Could it be that your border router inappropriately responds to directed traffic and that you are under a denial-of-service attack? If any of these questions suddenly makes your blood run cold, read on.

In this chapter, we will cover these questions and other risks that can severely impact reliable Internet connectivity for your organization, and we present techniques to mitigate the risk.

• Components of Reliable Connectivity Components that affect reliable connectivity.

• Exposing Weaknesses in Connectivity How attackers and hardware/software failures can take you down.

• Border Router Security Mitigating the risk of attack as well as hardware and/or software failure.

• Internet Gateways and Multihoming Utilizing multiple Internet gateways with BGP multihoming to mitigate the risk of gateway failures and denial-of-service attacks.

• Backup of Critical Device Configurations Backing up router, switch, and firewall configurations to enable rapid disaster recovery.

• Bandwidth Utilization Monitoring and managing bandwidth at your Internet gateways.

• Redundant and Spare Equipment Deploying redundant hardware and developing a hardware spare inventory plan to enable rapid disaster recovery.

• Geographic Distribution of Critical Systems Deploying systems running critical applications in geographically diverse locations on your network, and using anycast.