 new version.</p><p>A common use case is to migrate traffic gradually from one version of a microservice
to another. In Istio, you accomplish this goal by configuring a sequence of rules
that route a percentage of traffic to one service or another. In this task, you will send
50% of traffic to <code>reviews:v1</code> and 50% to <code>reviews:v3</code>. Then, you will
complete the migration by sending 100% of traffic to <code>reviews:v3</code>.</p><h2 id=before-you-begin>Before you begin</h2><ul><li><p>Setup