What is the 'Umbrella Defence' in Rugby?

The Umbrella Defence in Rugby is a defensive structure that teams can adopt. This structure is most well known for being adopted by the Springboks and England.
This defensive structure involves the linespeed of the defence being led by the outside players, more specifically the wingers. The aim of this defensive system is to force the attack back into the inside areas of the pitch where more defenders will be. As well as this it aims to put pressure on the outside attackers forcing them to make errors and turning over possession.
However, this structure is a risky option, having high risk for high reward. There are a number of ways this system can be beaten. Firstly attacking depth can allow for the ball to be moved into the outside channels before it's shut down by the winger and creates an attacking opportunity. Also, a lack of inside connection and missed tackles can undermine the system. Finally, the last way an attack can counteract this defensive system would be the use of kicks to capitalise on the space behind in the outside channels.
If you enjoyed this video make sure to comment below about the structure, specifically what you like about it. Also mention if you think there are other better defensive systems out there, or any other tactics you'd like me to go through!