Segment based inter-networking to accommodate diversity at the edge

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26 Οκτ 2013 (πριν από 3 χρόνια και 7 μήνες)

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Segment based inter
-
networking to
accommodate 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 layer

routing, 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 segments)







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. buffer space)


sufficient storage that facilitate relaxed synchronization
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
accommodate 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 identifiers 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 transport 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 interfaces.




Evaluation


segment protocols


multi
-
wan
-
emu
toplogy


downloads 10MB file in vehicular scenario using the emulator









< aggregating uplink bandwidth >

< vehicular communication >

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, services ,devices
to be part of internet.