Diverse Network Servicesand

Remaining Challenges

SRCCS Winter 2005 Workshop on

Internet Modeling and Analysis

Sue B. MoonDivision of Computer Science

Dept. of EECSKAIST

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Diverse Data Sets in Korea

• Data from major ISPs– Non-existent in public

• Data from academia– DAGMON traces at KAIST– Long-term, sampled flow-level traces at POSTECH– 4-month-worth NetFlow traces at CNU

• Others– 3G video streaming service data– 2-day packet-level traces from a home network

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Diverse Data Sets in Korea

• Data from major ISPs– Non-existent in public

• Data from academia– DAGMON traces at KAIST– Long-term, sampled flow-level traces at POSTECH– 4-month-worth NetFlow traces at CNU

• Others– 2-day packet-level traces from a home network– 3G video streaming service data

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2005.11.23 at KAIST

FTP HTTP

P2P

OthersOthers

P2P

FTP

In Bits/Sec No. of Pkts / sec

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2004.12.9. at KAIST

FTP

HTTP

P2P

OthersOthers

P2P

In Bits/Sec No. of Pkts / sec

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REMOVE after chat with SY

• Previous slides upstream or downstream?• According to JH Youn

– Upstream 70%/85% (Bytes/Pkts) p2p– Downstream Web and VOD more dominant that p

2p.

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Home Networking in Korea

• Architecture– Simple, tree-like topology– To each home = 100ME– Internal links = 1GE– Outbound speed = OC-3 or up

• Reality in new apt complexes– Control home appliances thru the net

• washing machine, gas stove, lights, heater/airconditioner, door lock• by PDAs at home or remotely by cellphones/web access

– Replace DSL/cable lines– Will be "backbone" for home ubiquitous sensor network

• Need for remote monitoring– Lack of resources

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2004.12.11. at a Home Network

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Video Streaming over 3G

• Goals of Monitoring– To satisfy every user:

• High revenue-generating customers• More focus on per-user performance

• Challenges– E2E performance segmented over cellular

and wired networks– No integrated monitoring solutions yet– No good metric for overall/single-user

performance

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Provisioning for Interactive Streaming

• Interactive Streaming– Not a driving force behind b/w– A candidate for growing revenue

• Examples– VoIP gradually taking over PSTN traffic– Remote video viewing at door by cell phone– Online game traffic

• "Good" routing more important than bandwidth

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Routing in the Internet

Intra-domain:shortest path routing

Inter-domain:policy-based routing

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Issues in "Good" Routing

• Misbehaving routing protocols– BGP misconfigurations– Pathological behaviors– Frequent changes

• Even under normal circumstances– Transient behaviors– Inter/intra-domain routing not well understood

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Scenario for a Transient Routing Loop

In Normal Operation

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When a link fails, R1 is the first to detect.

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R3 is updated before R2.

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Finally R2 is updated, and the loop is resolved.

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CDF of Routing Loop Duration in Time

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VoIP experimental setup [Boutremans2002]

• Traffic injected in the network: – 200 byte UDP packets– every 5ms.

• Packets captured and timestamped at end-systems.

• Traceroute runs continuously during the experiment.

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Information Sources

• IS-IS & BGP listener logs • Router logs from both ends of

“failing” links• Controlled bi-directional VoIP traffic

between Reston and ATL• SNMP data

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Delays (1 sec timescale)

2 links down

~3.4ms

2 links up

~2.6ms

3 links down

3 links up

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When the two interfaces went down …

6.6 seconds

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When three links came back up …

For 30 secs packets follow a shorter path

Traffic “black-holed”for 1.745 seconds

Traffic “black-holed”for 0.975 seconds

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Approaches To Fix It

• Fine-tuning parameters– Timer values [Alattinoglu2002]

• Modify Routing Protocols– Suppress advertisement and perform local rerouti

ng using a backwarding table [Lee04]– Centralized path computation [Feamster04,Rexfor

d04]

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Our Approach

• Key Idea:– Find disjoint overlay path and send duplicate

packets• Assumptions

– Sender and receiver both within an AS– Bidirectional link weights– Extra income for extra b/w consumption

• Pros and cons– Advantages

• No modification to current infrastructure• Selective use by only those that need it

– Disadvantages• Extra b/w consumption

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Basic Ideas

source

destination

candidate relay nodes!!!

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Resilient to Failures

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Future Work

• Answer questions raised about diverse data sets

• Find best places for relay nodes in Inter-domain

BACKUP

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Summary: Local Convergence

• Convergence delay during failures hurts more• After IS-IS converges, extra delay due to FIB update

Experiment

IS-IS Convergence Service Disruptions

2 links down 5.1 sec 6.6 sec

2 links up 17.6 sec ~ 0 sec

3 links down 5.9 sec 8.0 sec

3 links up 17.5 sec 0.95 sec

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Causes and Open Questions

• Why only after 30 secs? – spf-interval set to 30secs

• What caused the 1.745 secs disruption?• Unknowsn in GSR architecture• What is the right timescale to propagate good

news?