Mobility Discussion(Mobility and Internet Signaling Protocols -00)

NSIS Interim Meeting in UKJune 3, 2004

Goals of This Work• This draft is meant as an applicability statement and

user guide of NTLP/NSLPs in mobile environments.• We seek to analyse different cases to see whether the

NSIS protocols could work with basic mobility• Making sure there are no initial design mistakes that break the p

rotocols in mobile environments • Start as analysis, end up as an applicability statement

showing where the NSIS protocols work and where they don't

• Some cases are not just mobility-specific• Stimulating further discussions related to the security & authoriz

ation issues in a mobile environment making use of the NSIS protocols

Short Problem Statement• Change of route and possibly change of MN IP

address• Latency caused by route change due to

mobility• Explicit routes• Path update (Local repair)

– Upstream local repair vs. Downstream local repair– Teardown

• IP-in-IP encapsulation• Peer (MN, CRN, or AR) failures• Ping-pong type handover

Main Issues Discussed• Analysis of various mobility scenarios in NSIS signaling• Crossover node discovery and Path update caused by

mobility and route change• Dead peer discovery• Case examples of NSIS signaling according to handover

cases• Interaction with mobility signaling (e.g., HMIPv6,

FMIPv6, CARD, and CTP)• Uni- and bi-directional state establishment, State

Management, and State establishment in network mobility and additional issues

• Security considerations in various scenarios such as MN as sender/receiver, multihoming scenarios, using context transfer, proxy scenario, and AAA interaction

Future Work• Restructuring of TOC

Abstract 1. Introduction 2. Terminology 3. Problem Statement 4. General Considerations 5. Mobility-Related Issues with NSIS Protocols 5.1 Specific Issues with NTLP 5.2 Specific Issues with QoS-NSLP 5.3 Specific Issues with NAT/FW NSLP 5.4 Common issues related to NTLP and NSLP 6. Applicability Statement 6.1 Global- and local-mobility scenarios 6.2 Failure scenarios 6.3 Use cases of Identifiers 6.4 Backward compatibility 6.5 Aggregation of end-to-end flows in mobility scenarios 6.6 Multihoming/make-before-break scenarios 6.7 When CN is mobile 6.8 Bi-directional state establishment in mobility scenarios 6.9 Refresh interval adjustment in RANs 6.10 Interactions with mobility-related protocols 6.11 Guidelines for Implementation of NTLP and NSLPs

7. Security Considerations

Abstract 1 Introduction 2 Terminology 3 Framework 4 Cross-over Node Discovery and Path Update 5 Dead Peer Discovery (DPD) 6 Case Examples 6.1 NSIS in the hard-handover case 6.2 Example of Signaling of an Anticipated Handoff

7 Multihoming-related Issues 8 Interactions with Mobility Signaling 9 Additional issues 9.1 Both End-Hosts are Mobile 9.2 Uni- and Bi-directional State Establishment 9.3 State Management 9.4 State establishment in Network Mobility 10 Guidelines for Designers of new NSLPs 11 Summary of Split of functionality 12 Security Considerations 12.1 MN as data sender 12.2 CN as data sender 12.3 Multi-homing Scenarios 12.4 Context Transfer 12.5 Proxy Scenario 12.6 Implications for the costs of a QoS resv.

Question• Do you think this mobility work (Applicability

statement for mobility support in NSIS protocols) would be valuable in NSIS WG?

• Should this be a WG item, to analyze the applicability of NSIS protocol in a mobile environment?

Backup Slides for further discussion

Terminologies (I)• Crossover Node (CRN)

– A Crossover Node is a node that for a given function is a merging point of two or more separate sets of state information, and not only a physical route splitting point. In the context of this draft, we can distinguish several logical (but not necessarily physically) different CRNs:

• NTLP/NSLP CRN• Upstream/Downstream CRN• Mobility/Routing CRN

– Currently, each CRN definition is not obvious, so comment on NSIS mailing list.

Terminologies (II)• Path Update

– The procedure for the re-establishment of NSIS state on the new path, the teardown of NSIS state on the old path, and the update of NSIS state on the common path due to route change or mobility.

– Upstream Path Update: • Path Update for the upstream signaling which is initiated by a

signaling initiator on the common path– Downstream Path Update:

• Path Update for downstream signaling which is triggered by a signaling initiator on the new path (e.g., MN, mobile agent, or an AR).

• Dead Peer Discovery (DPD)– The procedure for finding a dead NSIS peer due to a link or

node failure and due to a mobile node moving away.

AR1 AR

NAR

CRN

AR

1

2

3

• Resv message Resv message • Path messagePath message• Teardown messageTeardown message• RSVP session RSVP session

QoS Signaling in Mobility (II)• Resources Reservation in MIP-based access Networks

– How to fast re-establish the resources after handover?• Path Update• How to ferret a Crossover Node?

– How to delete the obsolete path after handover?

Crossover Node Discovery• Discovery

– Issue I• If the merging point is NOT NSIS-aware and can NOT

act as a crossover node?• Session_ID, flow_ID, Incoming interface, and Mobility

Object.

AR1 AR2

CRN(1)Switching

Fabric

interfaceSession ID Switching

Fabric

interfaceSession ID

Flow IDMO

CRN discovery (cont’d) Route Change vs. Mobility (I)• Approaches

– Coupled approach– Separated approach – At the NSLP level,

• CRN is determined by comparing the Source Identification Information (SII) contained in the incoming signaling message to that of previously stored in the node.

– At the NTLP level, • CRN discovery can be considered as an extension to the peer

discovery• (e.g., using GIMPS query-response)

• Mobility– may cause the change of the flow identifier.

• the flow identifier should be updated along the entire chain of NSIS entities

– A For each flow, a CRN is only discovered • Upstream CRN (UCRN) / Downstream CRN (DCRN)

CRN discovery (cont’d) Route Change vs. Mobility (II)• Route Change

– the flow identifier does NOT change after the standard route change

• If an unique Session ID is used– For each (upstream/downstream) flow,

• the route change results in forming a chain of divergence and convergence CRN pair in the network.

• Diverging CRN and Converging CRN

Diverging CRN

Converging CRN

• The existing RSVP The existing RSVP SessionSession• New RSVP session New RSVP session

Path Update • Localized QoS signaling

– Upstream Path Update• for the upstream signaling, it is initiated by a signaling

initiator on the common path (e.g., a CN, a HA, or a GFA/MAP).

– Downstream Path Update • for downstream signaling, it is triggered by a signaling

initiator on the new path (e.g., MN, mobile agent, or an AR)

OARNAR

DCRN

Sender

CN

OARNAR

UCRN

3

Receiver

CN

1

3

2 1

2

Path Update (cont’d)• Open issues

– In the Interworking with HMIPv6, • how can the nodes decide locally whether they are

indeed the UCRN?• Can the update of the flow identifier for the session be

considered only between an MN and an MAP to avoid end-to-end signaling?

– Can the teardown message be sent toward the opposite direction of the state initiator?

– When is the right time to delete the state along the obsolete path for fast handover of a ping-pong type?

– How can the crossover node be discovered in the specific multicasting/multihoming cases?

– How does the NAT/FW NSLP affect the CRN discovery?

State Management• Soft state

– It may be necessary to set the refresh timer value in a wireless network to a smaller value than that in the core (wired) network

– by manual configuration – by some adaptive technique

• Use of Refresh bit to efficiently • reserve resources• ‘PRE’ bit for preservation• ‘M’ bit for Mobility session

Ver type checksum

TTL

flag

reserved Length

1 Setting the timer (M bit)

MP

Length 5 1Refresh period R

State Management• Soft state

– It may be necessary to set the refresh timer value in a wireless network to a smaller value than that in the core (wired) network

– by manual configuration – by some adaptive technique (Our proposal)

• Use of Refresh bit to efficiently reserve resources• ‘PRE’ bit for preservation• ‘M’ bit for Mobility session

State establishment in NEMO• Aggregate reservation

– The solutions in the NEMO WG will support preservation of route aggregation in the network when flows of MNs (and/or fixed hosts) in a mobile network are sent to the same HA or CN.

• Issue– Pinball routing problem

• the nested mobile networks cause this issue because flows of each mobile network may transit multiple HAs through multiple bi-directional tunneling.

– Multihoming-related issue

Reservation Mode• Sender-Initiated

– the MN (as a sender) can initiate a reservation setup for its outgoing flows as soon as it has moved toward another AR.

• Receiver-Initiated– MN (as a sender) somehow has to inform the

receiver of its handover• Delayed signaling problem occurs

• Bi-directional reservation – The bidirectional data flows have the same end

points, but the path in the two directions does not need to be the same.

– a crossover node for downstream reservation may be different from that for upstream reservation

Mobility Event detection• Mobility Object

– To prepare immediate handover • i.e., for fast QoS re-establishment

– When an MN detects a handover (e.g., by layer 2 trigger),

• NSLP of the MN may set the MOBILITY object in the refresh message and sends it to the current AR (1).

• NSLP of the AR after receiving the movement information (2).

AR1AR2

AR3

AR4

candidate

Candidate CR

(1)

(2)(2)

Interaction with Mobility Protocols

• During handover– Movement Detection

• e.g., ‘RtSolPr’ message in Fast Handover for MIPv6– CARD & CT

• To fast re-establishment or pre-establishment

• After handover– NTLP/NSLP messages should be simultaneously sent with h

andover information • BU message in MIP

Dead Peer Discovery (DPD): Overview

• A dead peer can occur– A link or a network node, including the MN and CRN,

failed, or – The mobile node moved away without informing

NSLP/NTLP• The procedures for handling DPD should be

the same no matter why a peer is dead – because an NE discovering a dead peer cannot judge

the specific reason – DPD due to a link or node failure, and DPD due to an

MN moving away should trigger the same reaction

Dead Peer Discovery (DPD): Overview (cont’d)

• Dead peers should be discovered as soon as possible to minimize service interruption

• NSIS needs to find a different path• NSIS state needs to be set up along the new

path, and NSIS state needs to be torn down along the old path

• Care must be taken to terminate teardown at the CRN since the NSIS state on the common path should not be deleted

DPD: Failure Cases• Dead peers of interest in mobility scenarios

– CRN, MN, and AR • Only NSIS functions (i.e., NTLP/NSLP) of the

node may fail, or the physical hardware• An MN may either fail or move

DPD: Impact of Dead Peers• The failure of an NSIS CRN • A new CRN should be discovered immediately• The failure or movement of an MN may cause the 'inv

alid NR' problem • The failure of an AR may make the interactions with S

eamoby protocols (such as CARD and CT) impossible. – In this case, the neighboring peer closest to the dead AR ma

y need to interact with CARD and CT