1. Chapter Objectives After completing this chapter you will be able to: Describe why SCSP is needed Describe the three phases of SCSP and how they are implemented Define the sub-protocols of SCSP Describe how the SCSP protocol is used with MARS and NHRP

2. Local Server (LS) Directly Connected Server (DCS) Remote Server (RS) LS RS DCS Server Group A LS RS DCS Server Group B SCSP Topology Model

3. SCSP Phases

4. LS DCS Hello Sender ID Receiver ID Hello Interval DeadFactor Hello Protocol

5. Down Bidirectional Connection Unidirectional Connection Waiting Hello Protocol States

6. DCS 1 LS DCS 2 Cache State Advertisement Summary Records (CSAS records) LS CSAS Records DCS 1 CSAS Records DCS 2 Cache Alignment Protocol

7. Down Cache Summarise Update Cache Master/Slave Negotiation Aligned Cache Alignment Protocol States

8. Changes of State in the Cache of the LS LS DCS Add an entry to your cache Remove an entry from your cache Cache entry has been modified Cache entry has timed out Cache State Update Protocol

9. MARS NHRP ATMARP Applications of SCSP

10. MARS Servers Cache synchronised with Sub Cache B Sub Cache A Sub Cache B Cache synchronised with Sub Cache A

11. NHRP Servers All NHRP servers in the same LIS are in the same server group An NHRP client registers with only one NHRP server but may use any NHRP server within the server group