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Diverse Network Services and Remaining Challenges. SRCCS Winter 2005 Workshop on Internet Modeling and Analysis Sue B. Moon Division of Computer Science Dept. of EECS KAIST. Diverse Data Sets in Korea. Data from major ISPs Non-existent in public Data from academia - PowerPoint PPT Presentation
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Diverse Network Servicesand
Remaining Challenges
SRCCS Winter 2005 Workshop on
Internet Modeling and Analysis
Sue B. MoonDivision of Computer Science
Dept. of EECSKAIST
2
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
3
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
4
2005.11.23 at KAIST
FTP HTTP
P2P
OthersOthers
P2P
FTP
In Bits/Sec No. of Pkts / sec
5
2004.12.9. at KAIST
FTP
HTTP
P2P
OthersOthers
P2P
In Bits/Sec No. of Pkts / sec
6
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.
7
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
10
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
11
Routing in the Internet
Intra-domain:shortest path routing
Inter-domain:policy-based routing
12
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.
19
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
22
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
25
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
29
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
30
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?
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