A single-homed internet connection is prone to failure and should not be used for mission critical applications. For this reason, it is usually not sufficient for an organization.
There are three main causes of outage associated with this lack of redundancy.
- Link failure – cable failure or construction crew severing a cable path
- Device/Gateway failure – the local CE router fails due to power outage, hardware issue, or software issue.
- ISP failure – Includes both internet slowness and an outage at the ISP
Stuck-in-Active: Journal of an IT-Network Administrator 