Link Characteristics Information conveyance

draft-korhonen-mobopts-link-characteristics-ps-01

Jouni Korhonen, Soohong Park, Ji Zhang, Cheulju Hwang, Pasi Sarolahti

Background

• How to make upper layers (e.g. transport) to adapt better after a handoff? Maybe explicit e2e signaling of crosslayer information between communicating peers could be used...

• In the IETF#65 we showed some experimental (simulations) results of utilizing local link information as part of TCP Quick-Start during the vertical handoffs

• The latest Problem Statement:– draft-korhonen-mobopts-link-characteristics-ps-01

Problem Statement

• IP mobility enabling protocols are– Designed to isolate transport and upper layer protocols from the

mobility events– Operating on top of the link layer without proper e2e dialogue of

the access network characteristics• Sharing the local sub-path characteristic information with

the remote communicating nodes is not supported– e.g. the wireless access link is likely the bottleneck on the end-

to-end communication path and often represent a significant portion of the end-to-end delay

• Transport layer congestion control algorithms often fail to respond fast enough to such changes or react in a wrong way when the path characteristics suddenly change. – Sharing the local sub-path characteristics information allows the

remote end to detect and react faster to the significant changes in the end-to-end path properties

Major changes since -00 draft

• It was clarified that the last hop & link knowledge is not really enough– The whole path should be considered.. the immediate question

is then how to do this based on the ‘local’ sub-path information– Local sub-path changes could serve as an indication to

reconsider the path characteristics and in some cases to set known upper limits (e.g. known max RTTs, MTUs, etc)

• Not all path characteristic changes are due mobility.. • Definition of the locality is not limited to the first hop

– Sub-path can extend beyond local access link..• Link information monitoring function

– Addition of MIH framework suitability considerations• Classification of explicit notification mechanisms

– Discussion on possibilities for end-to-end information delivery

Need for e2e Path Info –Current Situation

R

R

R R

R

R

R

Routers mark packets or process E2E signaling messages to ensure that

Data Traffic / Signaling Traffic

FeedbackMechanismusing signalingprotocol

Assumption:

All routers on path support wanted feature

Use Local Sub-Path Information

R

R

R R

R

R

R

Use local knowledge about

sub-path characteristics

Data Traffic

FeedbackMechanism eitherusing protocol specific extentionsor a new signalingprotocol

Assumption:

Significant changes in access link / sub-path can initiate feedback mechanism

R

Discussion Items

• Relation to TERNLI?– This work could be one key work area within TERNLI scope?

• About information..– What can be done with 1) local link, 2) sub-path or 3) full path

information and how to get that information?– What is actually needed to initiate some further actions?– What data to collect and deliver to the other end?– How to use to link/sub-path information on both ends?– Local use of the sub-path information..

• Various mobility protocols/application layer protocols and their interactions

• Generic end-to-end signaling protocol?– Both in-band and out-of-band should be considered

Related (ongoing) work

• draft-korhonen-mobopts-delivery-analysis-00 (analysis on e2e information delivery options)

• draft-ietf-tsvwg-quickstart-03

• draft- schuetz-tcpm-tcp-rlci-00

• draft-iab-link-indications-04

• RFC 3168 (ECN)

Questions.. Comments?