Meta-Headers: Top-Down Networking Architecture with...
Transcript of Meta-Headers: Top-Down Networking Architecture with...
IEEE GLOBECOM FutureNet, Miami, FL, Dec 2010 1
Meta-Headers: Top-Down Networking Architecture with Application-Specific Constraints
Murat Yuksel University of Nevada, Reno
Reno, NV
http://www.cse.unr.edu/~yuksem
IEEE GLOBECOM FutureNet, Miami, FL, Dec 2010 2
Motivation: The trends
The variety of applications possible is increasing, especially in wireless wireless peer-to-peer, mobile data, community
wireless The size is increasing:
million-to-billion nodes The dynamism is increasing:
vehicular networks, sensor networks, MANETs
What is unavoidable?: More dynamism, more disruption tolerance, more entities, and more varieties
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Motivation: The big picture
(a) OSI
Transport
Network
Data Link
Physical
Session
Presentation
Application
(b) Wireline
Transport (TCP, UDP)
Network (IP)
Data Link (Ethernet 802.3)
Physical (Fiber, Cable)
Application
(c) Wireless
Transport (TCP, UDP)
Network & MAC (IP, Mobile IP,
802.1x)
Physical (RF, Fiber, Cable)
Application
(d) MANET, peer-to-peer
?
Network & Routing
?
Application
Physical (RF, FSO, Fiber, Cable)
App
licat
ion
-Spe
cifi
c
Har
dwar
e-Sp
ecif
ic
Net
wor
k-Sp
ecif
ic
Static Structured Layered invariants
Mobile, ad-hoc, dynamic Unstructured Cross-layer & layered invariants
We need a systematic way of implementing vertical components to avoid an unhealthy monolithic stack architecture.
Economics always has the bigger force: economically attractive applications will keep forcing more vertical components into the stack!
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Motivation: Response to the trends
Wireless research has been responding with optimizing via cross-layer designs adding custom-designed vertical components to the
stack Old hat: layered vs. cross-layer tradeoff
Bottom-up cross-layer has been the main approach Scarcity of wireless resources dominated the
economics
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Motivation: Response to the trends A paradigm shift: wireless resources are
becoming massively available Community wireless WiFi hotspots Google WiFi, AT&T Metro WiFi
Spectrum resources may still be scarce but connectivity is already ubiquitous
The key metric to optimize is becoming application utility rather than the wireless resources
App-specific vertical designs are needed..
We need top-down cross-layer designs in addition to the traditional bottom-up ones.
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Why not continue merging layers?
Merging layers: A greedy approach Makes it hard to standardize – bad for sw engineering
Which layers must be absolutely isolated? Application, Network, Physical?
Integrating lower level functions with a higher layer function will prevent them becoming a substrate for other higher layer protocols Cellular provisioning in the US – jailbreaks
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Motivation: Application Layer Framing (ALF)
Layering was a main component of the e2e architecture..
“a major architectural benefit of such isolation is that it facilitates the implementation of subsystems whose scope
is restricted to a small subset of the suite’s layers.” Clark and Tennenhouse, SIGCOMM’90
But, Integrated Layer Processing (ILP) was there too! To achieve better e2e efficiency and resource optimization ILP never become a reality due to the lack of a systematic way
of doing it. An ALF-based approach is needed:
network protocol services at lower layers can best be useful when applications’ characteristics and intents are
conveyed to the lower layers.
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Meta-Headers: A vertical design tool
A packet meta-header: vertically travels across the network stack establishes a vertical communication channel among
the traditional layers co-exist with the traditional per-layer packet headers
Applications can communicate their intent across all the protocol layers by attaching the meta-headers to data.
<meta-headers, message>
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Headers vs. Meta-Headers Application
Layer 4
Layer 3
Layer 2
Layer 1
message
H4 message MH1 MH2 MH3 MH4
H3 H4 message MH1 MH2 MH3 MH4
H3 H2 H1 H4 message MH1 MH2 MH3 MH4
H3 H2 H4 message MH1 MH2 MH3 MH4
Traditional packet headers
Application-specific packet meta-headers
Application
Layer 4
Layer 3
Layer 2
Layer 1
Traditional packet headers
Application-specific packet meta-headers
Explicit Meta-Headers
message
message MH4 MH3 MH2 MH1
MH1 message H4 MH3 MH2
H2 MH1 H3 message H4
MH1 MH2 message H4 H3
H3 H2 H1 H4 message
Implicit Meta-Headers
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Meta-Headers: Demultiplexing
H3 H4 message MH1 MH2 MH3 MH4
Layer 3
Layer 4
Protocol 1 Protocol 2
Dem
ulti
plex
ing
wit
h tr
adit
iona
l hea
ders
H4 message MH1 MH2 MH3 MH4
H4 message MH1 MH2 MH3 MH4
Layer 3
Layer 4
Service 1 Service 2
Dem
ulti
plex
ing
wit
h m
eta-
hea
ders
H3 H4 message MH1 MH2 MH3 MH4
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Informing Applications about Lower Layer Services
How will upper layers know about the service primitives of the layers lower than the one below?
Reactive – Meta-Headers in Reverse Direction detect lower layer services in an on-demand manner
as connections arise meta-headers rewritten by lower layers in reverse
direction Requires a closed-loop – connectionless or multi-
receiver services may not work
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Informing Applications about Lower Layer Services (cont’d)
Proactive – Pre-informed Designer inform layer k designers about services of layers k-2
and below apriori too much complexity as the number of lower layer
services increases – rank ordering might help May not be desirable by ISPs Regional service discovery via broadcasting –
connectionless
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End-to-End Coordination
Application
Layer 4
Layer 3
Layer 2
Layer 1
message
message MH4 MH3 MH2 MH1
MH1 message H4 MH3 MH2
H2 MH1 H3 message H4
MH1 MH2 message H4 H3
Traditional packet headers
Application-specific packet meta-headers
H3 H2 H1 H4 message
Application
Layer 4
Layer 3
Layer 2
Layer 1
Layer 3
Layer 2
Layer 1 H2 MH1 H3 message H4
MH1 MH2 message H4 H3
H3 H2 H1 H4 message
Optional feedback loop for conveying available L1-L3 services
1 Application at
source prepares meta-headers with default options and sets flags to probe
for available services
2 Meta-headers may
or may not get converted to
traditional headers.
3 Meta-headers are filled
with available L1-L3 services, and
optionally fed back to the source application.
4 Meta-headers are filled
with summary of available end-to-end L1-L4 services, and fed back to the source application.
5 Application at
source readjusts meta-headers for
joint vertical optimization of
end-to-end performance.
H3 H2 H1 H4 message
MH1 MH2 message H4 MH3
H2 MH1 H3 message H4
MH1 MH2 message H4 H3
MH1 MH2 message H4 MH3
MH1 MH2 message MH4 MH3
Feedback loop for conveying end-to-end
multi-hop L1-L4 services, possibly as a sequence of
options over multiple hops.
Optional feedback loop for local
optimization of last hop(s) of the end-
to-end path. SOURCE
ROUTER
DESTINATION
A dynamic end-to-end negotiation..
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An optimization perspective Application
Top-Down Value Choice Optimization Framework
Application-Specific View of the Network
Application-Specific Constraints
Value Choices
E (application-based
cost)
Q3 (per-layer
state)
B (quality constraints)
Meta-header probes questing lower layer services
Meta-headers filled with available services
Q2 (per-layer
state)
W2 (implicit) (per-layer constraints)
Network
Network State Information
Network Resource Constraints
Links
Link State Information
Link Resource Constraints
W3 (implicit) (per-layer constraints)
Lagrange multipliers (pieces of E)
Lagrange multipliers (pieces of Q2 and Q3)
Vertical optimizations are possible
More dynamic
Meta-headers as Lagrange multipliers
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Summary A top-down networking architecture with meta-
headers Vertical optimizations at finer temporal and spatial
granularity A variety of top-down optimizations:
Top-down routing (layers 5, 3) Top-down QoS/value management (layers 5, 3, 2) Top-down dynamic transport (layers 4, 3, 2)
A new class of optimization problems aiming to improve joint performance of multiple layers while respecting the isolation among them.
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Thank you!
THE END
This work is supported in part by the U.S. National Science Foundation awards 0721600 and 0721609.
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An optimization perspective Meta-header
probes questing
paths
Application
Top-Down Routing Optimization Framework
Application-Specific View of the Network
Application-Specific Constraints
Routing Choices
Meta-headers filled with
available paths
E (application-based
path costs)
Q (link states or path-vectors)
B (path quality constraints)
W (implicit) (link weights)
Network
Network Topology Information
Network Resource Constraints
Lagrange multipliers
(pieces of E)
Lagrange multipliers
(pieces of Q)
Vertical optimizations are possible:
More dynamic
Meta-headers as Lagrange multipliers