1. IEEE 802.21 MEDIA INDEPENDENT HANDOVER DCN:21-06-0680-00-0000
Title: Multi-Hop Model for ES and CS
Date Submitted: July 14, 2006
Presented at IEEE session in San Diego
Authors or Source(s):
Yoshihiro Ohba and Subir Das
Abstract: This document proposes a scenario where ES and CS message exchanges can occur across multiple MIHF hops.

2. IEEE 802.21 presentation release statements
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3. Background
IS multi-hop scenario is described in IS-Multihop-Scenario.ppt
Accepted in July ad-hoc meeting in Singapore
There was a comment that the same scenario is applicable to ES and CS
“ACTION: Submit appendix text for ES & CS” ( AdHoc-Contribution-Status.doc)
This contribution is made to make the action

4. Difference from IS multi-hop model
ES and CS use MIHF ID while IS does not
Source and destination MIHF IDs are replaced by each MIHF in the message forwarding path
Each MIHF on the path acts like an ALG (application layer gateway)
As a result, MN’s MIHF ID carried in the variable header part of a MIH message forwarded in the first MIHF hop will not be carried in the MIH message forwarded to the subsequent MIHF hops
MN’s MIHF ID will need to be carried in MIHF payload part of MIH message in the subsequent MIHF hops

5. Proposed Changes Insert a New Appendix
“Annex E Multi-Hop Operation for Event and Command Services
In Event and Command Services, an MIH PoS may acts as an intermediary entity which forwards MIH messages carrying ES or CS payloads (i) between a mobile node and a non-PoS MIH, (ii) between a mobile node and another MIH PoS or (iii) between another MIH PoS and a non-PoS MIH. The role of such an intermediary is to splice an ES or CS transaction path into multiple transaction segments. The two MIH nodes of a transaction segment act as an ES or CS client and server. Existence of other transaction segments of the same transaction path are not visible to the MIH nodes, i.e., an MIH node will not know whether its MIH peer is further forwarding ES or CS messages to another MIH node.
Source and destination MIHF IDs of each ES or CS message received from the previous hop transaction segment are replaced with the source and destination MIHF IDs of the next hop transaction segment by each MIHF in the message forwarding path. As a result, MN’s MIHF ID carried in the variable header part of an MIH message in the first hop transaction segment will not be carried in the variable header part of the MIH message forwarded to the subsequent hops. In this case, the MIHF ID of MN in addition to other TLVs is carried in the MIHF payload part of MIH message in the subsequent MIHF hops. Examples of ES/CS intermediaries are shown in Figure 33.”
Insert Figure 33 (see next slide)

6. Figure 33: ES and CS Intermediaries
ES/CS Transaction segment
ES/CS Transaction segment
MIH MN
MIH
PoS1
Non-PoS
MIH1
Client
Server
Client
Server
ES/CS Intermediary (i)
Src/Dst MIHF IDs =
MIH MN/MIH PoS1
Src/Dst MIHF IDs =
MIH PoS1 / Non-PoS MIH1
MN’s MIHF ID carried in
MIH payload part
ES/CS Transaction segment
ES/CS Transaction segment
ES/CS Transaction segment
MIH
PoS2
Non-PoS
MIH2
MIH MN
MIH
PoS1
Client
Server
Client
Client
Server
Server
ES/CS Intermediary(ii)
ES/CS Intermediary(iii)
Src/Dst MIHF IDs =
MIH MN / MIH PoS1)
Src/Dst MIHF IDs =
MIH PoS1 / MIH PoS2
MN’s MIHF ID carried in
MIH payload part
Src/Dst MIHF IDs =
MIH PoS2 / Non-PoS MIH1
MN’s MIHF ID carried in
MIH payload part