1 © NOKIA FILENAMs.PPT/ DATE / NN Header Compression Context Relocation in IP Mobile Networks Rajeev Koodli, Manish Tiwari and Charles E. Perkins

2 © NOKIA FILENAMs.PPT/ DATE / NN Problem When a Mobile Node (MN) using header compression moves from an IP access point to another, compression context relocation is needed to continue seamless header compression operation at the new network node R1 R2 Compressed packet stream Uncompressed packet stream discard New Router Previous Router

3 © NOKIA FILENAMs.PPT/ DATE / NN Proposal MN detects header compression capability at the New Router subsequent to handover MN sends header compression context relocation request (HCREQ) in the Smooth Handover Initiate (SHIN) message The New Router responds back immediately if it has the required state available, e.g., in NCMA handover else sends a request to the Previous Router to furnish the state activates compression contexts upon successful reception of required state, and acknowledges the MN

4 © NOKIA FILENAMs.PPT/ DATE / NN Proposal.. The Previous Router responds to the New Router’s request for state transfer sends unsolicited SHREP message to proactively supply context information in NCMA handover

5 © NOKIA FILENAMs.PPT/ DATE / NN Basic Signaling Approach New Router R1 R2 Previous Router 1. SHIN Binding Update 2. SHREQ 3. SHREP

6 © NOKIA FILENAMs.PPT/ DATE / NN Compression Profile Type Compression Profile Type (CPT) This is an object that indicates what type of header compression is desired Possible types are: 1. IPv6/UDP header compression 2. IPv6/UDP/RTP header compression Each CPT is assigned an IANA Type Number A value of zero for the CPT has special meaning, and is reserved Media-specific profiles are possible

7 © NOKIA FILENAMs.PPT/ DATE / NN CPT contd.. An application requesting header compression indicates the type of CPT it wishes to use An application does not need to know how a CPT is implemented e.g., whether the compression algorithm uses a sliding window, sequence numbers etc.

8 © NOKIA FILENAMs.PPT/ DATE / NN Requirements Need for the visibility of CID at the IP layer regardless of how CIDs are generated, they must be available for IP to use to identify compression contexts Need for defining the context state for a given compression profile, the header compression state must be well-defined and fixed in size Need for defining the Filter for a context a Filter identifies the IP packet stream undergoing compression, and it may be supplied as part of the header compression state information MN, Router requirements outlined in the draft

9 © NOKIA FILENAMs.PPT/ DATE / NN Conclusion Context relocation is an important problem that needs to be addressed Address the requirements