The　prohibitive　cost　of　deploying　a　sophisticated　DNS-based　CDN　makes　anycast-based　CDN　an　attractive　alternative　for　new　or　small　CDN　operators.　In　anycast-based　CDNs,　user　requests　are　naturally　routed　to　the　＂closest＂　server　determined　by　Internet　routing.　For　the　operators,　however,　this　comes　at　a　cost-loss　of　control-how　the　traffic　is　routed　is　entirely　at　the　mercy　of　BGP　routing.　The　＂closest＂　server　may　be　overloaded,　or　simply　not　the　best　choice.　This　＂loss　of　control＂　undermines　the　scalability　of　anycast-based　CDN　architectures.　To　have　control　over　how　traffic　is　routed,　existing　work　either　requires　adding　a　large　amount　of　complexity　to　the　system　(high　Capex/Opex)　or　is　unable　to　achieve　precise　and　fine-grained　control.　This　paper　proposes　T-SAC,　a　scalable　anycast-based　CDN　architecture　that　capitalizes　on　the　programmability　and　flexibility　of　SDN/NFV,　enabling　fine-grained　traffic　redirection　among　CDN　servers.　T-SAC　achieves　precise　control　by　leveraging　a　load-based　redirection　algorithm　and　a　single　1-bit　no-redirect　flag.　We　implement　T-SAC　in　the　real　system　and　evaluate　its　performance　from　various　aspects　using　DASH　and　web　applications.　The　results　show　that　T-SAC　is　capable　of　redirecting　the　right　amount　of　traffic　at　the　right　time　to　the　right　servers,　making　the　system　highly　scalable.