Segment based inter-networking to accom-modate diversity at the edge

DCSLAB Cho wan-hee

Introduction Motivation

Many of these changes have occurred at the network edge

Diverse Internet access tech- blue-tooth ,ultra-wide-band

Edge devices- cell-phone, PDAs, sensors

Applications - content sharing , sensing app

Services supported by network - caching, mobile users

Segment based architecture Diversity at the edges is going to increase in

future

Goal : offer flexibility at different levels

Introduce Tapa, segment based architecture- Segment layer

corresponds to a portion of an end-to-end path that is homogeneous

best effort data delivery service to upper layerrouting, error control, congestion control service

Segment based architecture Transfer layer

supports e2e data transfers over multiple segments located on top of segments similar to how IP supports connectivity in today’s internet runs on Transfer Access Point(TAP)

Transport layer Implements e2e application semantics over transfer layer traditional transport protocols is already implemented

within segment layer deal with lost ADUs when TAP failures reorder ADUs that were delivered out of order (multiple seg-

ments)

Tapa illustrate the role of new layers in Tapa forwards application data units(ADUs) rather

than byte stream or packets

TAP What

glue required to combine multiple segments (ex. buf -fer space)

sufficient storage that facilitate relaxed synchroniza-tion between segments and end-points

offer optimizations such as multi-path and content discovery

functions transport layer can also accommodate the insertion of

services on the TAP caching : Web and other type caching typically supported at application level

Tapa configuration case segments can be very diverse and customized

for each environment can bypass IP and traditional link layer HOP for mesh access network

Transfer layer similar to IP in today’s internet Internet routing needs to establish routes in

large scale but fairly stable Tapa transfer layer establishes short paths(2-

segments) but path can be very volatile due to dynamic of the access network(mobility)

IP packet forwarding is optimized for high throughput despite large forwarding table

ADU forwarding is simple but needs to ac-commodate in-network services ex. Catnap

Transfer layer Control Plane

establish segments to set up e2e path enable the data plane to transfer ADUs over

them globally unique “identifiers” segment layer must be able to translate identi-

fiers into locators(ex. DNS for wired segments ,MAC addr for bluetooth)

use host-name as identifiers in our prototype needs congestion control over multi-segment

path to ensure that TAP buffers do not overflow

Transfer layer Data Plane

ADU can be defined in a flexible manner based on the requirements of the application.

(ex. whole file, chunk of file, MPEG frame in video tranfer)

use of ADU changes the interface between trans-port layer and applications, compared with socket API.

Transport layer support for semantic between endpoints and

network

ex) content is available in the cache of TAP - client may not trust the TAP (open wifi) - so client transport will request integrity check

from the end-point while TAP can serve the data in an application independent way

ex) video streaming - on mobile phone, low resolution video

Prototype design assumption : TAPs are being used in typical

home wireless access scenarios. two transfer mode

pull mode : applications use “get API” to retrieve an ADU

push mode : send ADU to particular node

Prototype design transfer layer

transfer ADUs and deliver them to higher other transfer service can be used (ex. Catnap ) once transfer layer assembles the whole ADU it

sends it to the transport layer

transport layer reliability ,ordering ,delegation semantics offer caching as a part of delegation semantic.

Case study (Catnap) Catnap allows a mobile client to sleep during

ADU transfers by intelligently shaping when data is sent on the wireless wired segment is the bottleneck(home wireless

scenario) implemented as a transfer service that runs at the

TAP

Evaluation how well support diversity

micro-benchmark to quantify Tapa overhead

Evaluation segment protocols

downloade of 10MB file with different segment protocols

swift optimization of using multiple segments scenario- multipexed different protocol segments (HOP +TCP)- different underlying tech (bluetooth + 802.11)- different ISP

We aggregate AP uplink bandwidth for efficient hand-off, to mask failures and for aggregate throughput of multiple in-

terfaces.

Evaluation segment protocols

multi-wan-emu toplogy downloads 10MB file in vehicular scenario using

the emulator

< aggregating uplink band-width >

< vehicular communica-tion >

Evaluation overhead

single-wan-emu and single-lan-emu topology Tapa-ir : push ADU , send ADU to particular node Tapa-pull : pull ADU, pull ADU by first retrieving its

id, and then retrieving data

< WAN > < LAN >

Conclusion seperation of segment / transfer / transport

Layer offer flexibility at different levels

segment level diverse protocols (HOP ,Bluetooth )

transfer level multi-path and content-centric optimization

transport level richer semantic (Caching)

this flexibility allows diverse applications, ser-vices ,devices to be part of internet.