Transcript Co* Projects : CoDNS, CoDeply, CoMon - ANLAB

Co* Projects :
CoDNS, CoDeploy, CoMon
KyoungSoo Park, Vivek Pai and Larry Peterson
Princeton University
7/16/2015
Co* Project
1st Asian PlanetLab Workshop
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Background : CoDeeN
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Academic Content Distribution Network
100+ proxy servers on PlanetLab
Improve web performance & reliability
Running 24/7 since June 2003
Roughly 3-4 million reqs/day aggregate
Highest-traffic project on PlanetLab
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How CoDeeN works
Request
Cache hit
CoDeeN
Proxy
Cache hit
Each CoDeeN proxy is a forward
proxy, reverse proxy, & redirector
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CoDeeN as Project Factory
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Deployment Issues
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CoDNS
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Reliable DNS service
CoDeploy
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Reliability/Security
Large file distribution
Dynamic URL rewriting
CoMon
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Monitoring infrastructure
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Local DNS Lookup Problems
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CoDeeN experiences DNS problems
Local DNS lookup failures
 5+ seconds delay for cached records
 Frequent & widely-distributed
Local DNS lookups important
 LDNS cache hit rate: 80-90%
Unpredictable service
 Directly affecting user-perceived latency
 Random delay in web browsing
 Critical in HTTP proxy, web crawlers and busy
mail servers
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Experiment For Local Problems
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Local name lookup every 6 seconds
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“yyy.domain” on xxx.domain at Planetlab
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Lookup should be handled locally
Failure criteria
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“planetlab-2.cs.princeton.edu” for
planetlab-1.cs.princeton.edu
5+ seconds of latency
zero answer
Rolling average of the past 100 queries
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Expected DNS Behavior
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planetlab3.flux.utah.edu
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ricepl-1.cs.rice.pl
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DNS Failure on Various Nodes
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planetlab1.cs.cornell.edu
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planetlab2.tamu.edu
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planetlab2.cs.uoregon.edu
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Possible Causes
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Packet loss
LDNS overloading
Cron jobs
Maintenance problems
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Solution? CoDNS
answer
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CoDNS
local
node
LDNS
CoDNS
LDNS
CoDNS
LDNS
LDNS
x
queries
CoDNS
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CoDNS
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Cooperative name lookup scheme
If local server OK, use local server
When failures, ask a peer for the lookup
Selecting nearby peers
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Liveness/Remote nameserver’s health
Send to improve cache locality
Remote request timeout
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Dynamically adjusted to local server’s health
Exponentially backed off for each remote query
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Evaluation
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Live traffic for one week for CoDeeN (20k - 30k)
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Finer-grained View
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Live traffic for one day
Effectively flattens the spikes
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Availability
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Add one ‘9’, from 99% to 99.9%
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For More Details
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CoDNS: Improving DNS Performance and
Reliability via Cooperative Lookups
KyoungSoo Park, Vivek S. Pai, Larry Peterson and
Zhe Wang
[OSDI04]
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Non-I2 nodes
CDN names lookup
CoDNS vs. TCP-based DNS
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1st Asian PlanetLab Workshop
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CoDeploy
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How to utilize the CDN infrastructure?
Large file(100’s MB) distribution
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No custom protocol/software
Preserves HTTP semantics
Dynamic URL rewriting
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Supports Akamai style CDN
CoralCDN [NSDI04]
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Large file distribution
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BitTorrent
Bullet [SOSP03]
SplitStream [SOSP03]
FastReplica [USITS03]
Download managers(Windows update,
Adobe download manger)
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Drawback
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Availability
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Only BitTorrent is deployed
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But doesn’t really cache – peers are active
downloaders
Complexity
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Custom protocols
Origin site needs special server, format
Client software also custom
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Our Approach
CDN
CDN
file
file0-1
Agent
CDN
file2-3
CDN
Server
file4-5
CDN
CDN
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Low-Level HTTP stuff
GET name/ranges
Header: blah
Header: blah
egress
HTTP/1.0 206 Partial
Range: start-end/length
Header: blah
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ingress
GET name
Range: bytes ranges
Header: blah
HTTP/1.0 200 OK
Content-length: piece length
New-header: obj length
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Dynamic URL Rewriting
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http://www.host.com/path
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file
Client
Server
http://proxy:port/capability/www.host.com/path
file
Client
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rewritten file
CDN
file
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Server
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Benefit
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Transparently distributing the load
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Avoiding slashdot effect
No setup at the browser
Cheap way of publishing popular
contents
Easily customizable
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Capability: access control
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CoMon
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PlanetLab monitoring infrastructure
Node level statistics
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Slice level statistics
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Uptime, cpu/memory usage, DNS failure rate
# proc, network BW, cpu/memory usage
New slicestat
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Provides slice level resource consumption
statisics
e.g. curl http://localhost:3100/slicestat
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QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
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QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
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QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
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QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
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1st Asian PlanetLab Workshop
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Direction
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Which node is usable?
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sshable, DNS lookup, cpu/memory, file
descriptor availability
Which slice is going astray?
What are the typical experiments?
Automatic detection of overloading
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More info
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Contact us!
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[email protected]
CoDeeN [USENIX04]
 http://codeen.cs.princeton.edu/
CoDNS [OSDI04]
 http://codeen.cs.princeton.edu/codns/
CoDeploy
 http://codeen.cs.princeton.edu/codeploy/
CoMon
 http://codeen.cs.princeton.edu/comon/
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