Mark says to 電訊台 用一個具體例子就明：你係紅磡poly,對上edge就係紅磡exchange，再上嘅aggregation就係佐敦exchange。如果mesh左嘅話，行bus line會collide,行p2p all mesh嘅結果係你個edge可能會走左去元朗exchange 或者係香港仔exchange,之後再route返去佐敦。對你就lag,對telco就分唔清faultpoint 同cost太大