The Internet was not designed to support the fast delivery of website applications. And caching– does not adequately address the performance requirements of dynamic, web-based applications. In this presentation, we will go over the differences, challenges and methodology for accelerating dynamic and static/cached content with a content delivery network (CDN).
These slides were presented at the 2014 Velocity conference at the Santa Clara Convention Center in Santa Clara, CA United States
For more information please visit cdnetworks.com.
4. CDNETWORKS.COM
PoP 3
PoP 2
PoP 1
Tier 3 Networks
(Multi-homed ISP)
IXC
Tier 1 Networks
Tier 3 Networks
(single homed ISP)
Tier 2 ISPs
Global Network
Providers
Internet Users
Broadband
Providers
Tier 2 Networks
Regional
ISPs,
University
Networks
Transit
Transit
Transit
Transit
Peering
THE GLOBAL INTERNET IS COMPLEX
5. INTERNET RTT LATENCY
DISTANCE
SPEED OF LIGHT
70 ms
150 ms
LONDON
NEW YORK
500 ms SHANGHAI
GLOBAL INTERNET CHALLENGES
CDNETWORKS.COM
SAN FRANCISCO
6. GLOBAL INTERNET CHALLENGES
NETWORK PROBLEMS
NETWORK OF NETWORKS BOTTLENECKS
PACKET LOSS
CONGESTION
RETRANSMISSION
CDNETWORKS.COM
SAN FRANCISCO
USER
7. MULTIPLE RTTs FOR CONNECTION NEGOTIATION
GLOBAL INTERNET CHALLENGES
INEFFICIENT PROTOCOLS / RTT MULTIPLIER
•CHATTY PROTOCOL
•TCP SLOW START
•TENS OF BACK & FORTH ROUND TRIPS
•30-50 RTTs FOR ONLY 1 PAGE
•CONNECTION LOAD AT ORIGIN
CDNETWORKS.COM
SAN FRANCISCO
FILE
USER
17. STATIC (http/s)
SET TTL
DYNAMIC (http/s)
DYNAMIC ACCELERATION VS. WHOLE SITE DELIVERY
ENCRYPTED
SOME CDNs CAN ACCEPT ENCRYPTED TCP CONNECTION & ACCELERATE IT
CONTENT TYPES
CDNETWORKS.COM
23. DYNAMIC REPLICATION
GENERALLY CANNOT CACHE/REPLICATE PERSONALIZED RESULTS
NEED TO DETERMINE CONSISTENCY REQUIREMENTS
THEN DESIGN ORIGIN ARCHITETURE TO SUPPORT
CDNETWORKS.COM
24. REPLICATION – DYNAMIC CONTENT
CONSISTENCY QUESTIONS
HOW MANY HITS ON MY WEB PAGE?
CLOSE ENOUGH IS OK
HOW MANY PEOPLE VIEWED MY LINKEDIN PROFILE?
UPDATED HOURLY IS OK
I WANT TO BUY SEAT 11B ON AN AIRPLANE?
CAN ONLY SELL 1X
PROBLEMS IF SOLD MORE THAN 1X
CDNETWORKS.COM
25. REPLICATION – DYNAMIC CONTENT
CONSISTENCY APPROACHES
WEAK
BEST EFFORT
ACCEPTABLE FOR SOME LOST DATA
EXAMPLE: WEB PAGE COUNTER OR VOIP
EVENTUAL
DATA OFTEN PUT IN “WORK QUEUE”
EXAMPLE: PROFILE VIEWS
STRONG
RELATIONAL DATABASES
USE TRANSACTIONS
WAITS FOR CONFIRMATION
EXAMPLE: SEAT 11B
CDNETWORKS.COM
26. REPLICATION – DYNAMIC CONTENT
DATACENTER IMPACT:
WHAT ABOUT SINGLE DATACENTER?
WEAK, EVENTUAL, STRONG:
EASY, BUT SPOF
SPEED & RELIABILITY EXCELLENT
WHAT ABOUT MULTI DATACENTER?
WEAK, EVENTUAL:
RELATIVELY EASY, HARDER THAN SINGLE DATACENTER THOUGH…
STRONG
MUCH MORE DIFFICULT
THINK BANK TRANSACTION
CDNETWORKS.COM
27. • What About Multi-Datacenter?
– If you need to do it, you need to do it…
Source: http://www.cs.usfca.edu/~srollins/courses/cs682-s08/web/notes/transactions.html
REPLICATION – DYNAMIC CONTENT
CDNETWORKS.COM
28. Source: http://www.cs.usfca.edu/~srollins/courses/cs682-s08/web/notes/transactions.html
REPLICATION – DYNAMIC CONTENT
OPTIONS FOR MULTI-DATACENTER
DON’T
JUST BUILD AS RELIABLE OF A SINGLE DATACENTER SOLUTION AS YOU
CAN
2+ DATACENTERS - GOOD
MASTER/REPLICA, MULTI-MASTER
GENERALLY NOT STRONG CONSISTENCY (TERMS VARY)
MIGHT LOSE SOME ACTIVE AND VERY RECENT DATA
2+ DATACENTERS - EXCELLENT
2 PHASE COMMIT/PAXOS
THINK OF BANKING & SEAT 11B
CDNETWORKS.COM
29. REPLICATION – DYNAMIC CONTENT
Single Origin
3 Datacenters
CDN (CDNetworks)
ASSUME YOU HAVE A 2 OR 3 DATACENTER SOLUTION
DO YOU STILL NEED A CDN?
CDNETWORKS.COM
31. THESE ARE SOME COMMON TECHNIQUES
DIFFERENT CDNs USE DIFFERENT TECHNIQUES
MOST CDNs DO NOT SHARE TECHNIQUES
BOTTOM LINE – PERFORMANCE RESULTS MATTER!
DISCLAIMER: DYNAMIC ACCELERATION
CDNETWORKS.COM
32. TCP CAN BE VERY SLOW
http://asperasoft.com/technology/transport/fasp/#tcp-464
35. TLS/SSL OFFLOAD
NO: SSL OFFLOADING
DWA EDGE
WITH: SSL OFFLOAD
EDGE SERVER WITH SSL CERTIFICATION ENCRYPTS & DECRYPTS ON IT’S
OWN TO REDUCE ORIGIN LOAD
ORIGIN ORIGIN
CDNETWORKS.COM
36. DYNAMIC CONTENT
NO: CACHING, COMPRESSION,
CONN. POOLING OR KEEP ALIVE
DWA EDGE
WITH: COMPRESSION,
CONN. POOLING AND KEEP ALIVE
CONTINUOUS CONNECTIONS BETWEEN EDGE & SHIELD; & SHIELD + ORIGIN REDUCE
ROUND TRIPS FOR TCP OPEN & CLOSE CONNECTION
DWA SHIELD
PERSISTANTCONNECTIONS
ORIGINORIGIN
FILEPARTSNOTCOMPRESSED
CDNETWORKS.COM
37. OPTIMALLY TUNED TCP LINKS
LONGRESPONSETIME
HIGH LATENCY
DWA Edge
LOW LATENCY
WITH LARGE WINDOWS, FAST RETRANSMIT, FINE GRAINED RETRANSMISSION TIMEOUTS
AND FAST RECOVERY
DWA Shield
LOW LATENCY
ORIGIN
CDNETWORKS.COM
39. DYNAMIC - ENCRYPTED
HAVEN’T TALKED ABOUT THIS YET
SOME BANKING & ECOMMERCE TRANSACTIONS WANT
ACCELERATION, BUT CAN’T SHARE CERTIFICATE
NETWORK ACCELERATION
SIMILAR TO DYNAMIC ACCELERATION, BUT NOT HTTP, SO CAN’T
READ HEADERS, JUST SEE IP PACKETS
ACCELERATION TECHNIQUES AT LOWER LAYER
CDNETWORKS.COM
43. DOMAIN NAME SYSTEM
EVERY LINK
UNICAST
UNIQUE IP ADDRESS
ANYCAST
SAME IP ADDRESS
LDNS
REALLY, WHAT IS USED FOR GEO LOCATION
EDNS CLIENT SUBNET
WAY FOR LDNS TO PASS BACK END USER NETWORK ADDRESS CDNETWORKS.COM
48. CDN BEST PRACTICES
DETERMINE DOMAINS: STATIC, DYNAMIC, & ENCRYPTED CONTENT
GLOBAL CUSTOMERS = GLOBAL CDN & GLOBAL DNS
DON’T USE ROOT DOMAIN FOR WEBSITE
HAVE PRIMARY & BACKUP ORIGINS
SET TTL HEADERS ON CONTENT & DNS
BE AWARE CDNS SEND EXTRA HEADERS, USE IF DESIRED
USE APIs FOR CDN AUTOMATION
CDNETWORKS.COM
49. CDNS CAN OVERRIDE
SOME CDNS CAN RUN “RULES” AT EDGE
OVERRIDE MARKETING TEAM
IMMEDIATE EFFECT
REWRITE URL
SEND REQUESTS FROM “1.JPG” TO “OLD/1.JPG”
REDIRECT URL (301/302)
“http” to “https”
OVERRIDE HEADER
CACHE-CONTROL: MAX-AGE
CACHE-CONTROL: NO-STORE
CDNETWORKS.COM
50. CDNS CAN OVERRIDE
CONTENT VARIATION
USE CORRECT index.html BASED ON COOKIE OR GEO LOCATION
REFERRER CHECKING
BLACK/WHITE LIST
GEO CONTROL
ALLOW/DENY CONTENT BASED ON GEOGRAPHY
ORIGIN REQUEST HEADERS
PASS
ORIGIN FAILURE
SET BACKUP
DELIVER STALE CONTENT
RETURN 503 (REDUCE ORIGIN LOAD)
CDNETWORKS.COM