IEEE 802.21 MEDIA INDEPENDENT HANDOVER DCN: 21-07-0199-01-0000 Title: Comments on NET-SAP Date Submitted: May, 15, 2007 Presented at IEEE 802.21 session #20 in Montreal Authors or Source(s): Angelo Centonza, Eleanor Hepworth, Robert Hancock Abstract: This contribution suggests some modifications to the NET_SAP to reduce complexity, and remove ambiguities (also addresses comment 4150) 21-07-0199-01-0000

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MIH_NET_SAP Currently the MIH_NET_SAP provides primitives to manage connection oriented transport sessions, and to send data. Downside of requiring the MIH to explicitly manage the transport layer in this way is that it has to do things like decide when to listen/set up the socket, when to invoke L3 security mechanisms etc. which is unnecessary complexity in the MIH layer. We’ve also half re-invented the sockets API, and it’s not clear why this is necessary in the 802.21 standard. Why does the MIH need to have visibility of transport layer state – what benefit does this provide? 21-07-0199-01-0000

MIH_NET_SAP and MIH_LINK_SAP P25, link 38, P33 line 14 state: Replace “For all transport services over L2, the MIH_NET_SAP uses the primitives specified by the MIH_LINK_SAP” with “For all transport services over L2, the MIH_NET_SAP shall rely on the primitives specified by the MIH_LINK_SAP” 21-07-0199-01-0000

Proposal Make it simpler. A single interface that the MIH layer invokes to send a message using whatever transport is available below (TCP, UDP, DCCP, SCTP, aYetToBeInventedP) Flags in the primitive indicate to the transport *how* the message should be sent (reliably etc.) but makes no assumption about what protocols are used to achieve it Better future proofing properties The MIH can operate in blissful ignorance of things like socket status, whether the socket needs to be reset, etc. etc. – makes MIH stateless MIH_LINK_SAP and MIH_NET_SAP are better aligned MIH Send message (send reliably) Message sent successfully Comment: the MIH shall still be able to know which L2 is used and whether the L4 is reliable or not. Transport (black box) 21-07-0199-01-0000

Suggested Modifications #1 Modify the “description” field for the Reliable Delivery Flag in MIH_TP_Data.request (7.6.4.1) and MIH_TP_Data.indication (7.6.4.2) from: “Indicate whether an acknowledgement is required.” to “Indicate that the data MUST be sent reliably and an error generated if delivery fails” Substitute the status row in the semantics section MIH_TP_Data.confirm (7.5.4.4.2) with the following: Status Enumerated 0-5 Status of operation: 0 Success 1 Unspecified Failure 2 Rejected 3 Authorization Failure 4 Network Error 5 Success with unacknowledged transport only General positive feeling that a FALSE flag shall be present. Question from Roger Communication (operator): the data sent via TP_DATA are only signalling. Why there shall be an unreliable delivery if the only messages transported are signalling? (I quite do not understand why only signalling messages are transported) 21-07-0199-01-0000

Suggested Modifications #2 The following primitives should be removed (7.6.1-7.6.3): TP_Connect TP_Reset TP_Disconnect 21-07-0199-01-0000