8- dns - CSE 486/586 Distributed Systems Domain Name System...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
CSE 486/586, Spring 2012 CSE 486/586 Distributed Systems Domain Name System Steve Ko Computer Sciences and Engineering University at Buffalo
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
CSE 486/586, Spring 2012 Last Time Global states A union of all process states Consistent global state vs. inconsistent global state Total ordering Interleaving of events to get a single sequence Run , linearization (consistent run) The “snapshot” algorithm Take a snapshot of the local state Broadcast a “marker” msg to tell other processes to record Start recording all msgs coming in for each channel until receiving a “marker” Outcome: a consistent global state Why the snapshot algorithm is meaningful 2
Background image of page 2
CSE 486/586, Spring 2012 Recap 3 P1 P2 P3 e1 0 e2 0 e2 3 e3 0 e1 3 a b M e11, 2 M 1- P1 initiates snapshot: records its state (S1); sends Markers to P2 & P3; turns on recording for channels C21 and C31 e21, 2,3 M M 2- P2 receives Marker over C12, records its state (S2), sets state(C12) = {} sends Marker to P1 & P3; turns on recording for channel C32 e1 4 3- P1 receives Marker over C21, sets state(C21) = {a} e32,3 ,4 M M 4- P3 receives Marker over C13, records its state (S3), sets state(C13) = {} sends Marker to P1 & P2; turns on recording for channel C23 e2 4 5- P2 receives Marker over C32, sets state(C32) = {b} e3 1 6- P3 receives Marker over C23, sets state(C23) = {} e1 3 7- P1 receives Marker over C31, sets state(C31) = {}
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
CSE 486/586, Spring 2012 This Week’s Question How do we organize the nodes in a distributed system? Up to the 90’s Prevalent architecture: client-server (or master-slave) Unequal responsibilities Now Emerged architecture: peer-to-peer Equal responsibilities Studying an example client-server: DNS (today) Studying peer-to-peer as a paradigm (not just as a file-sharing application) Learn the techniques and principles 4
Background image of page 4
CSE 486/586, Spring 2012 Separating Names and IP Addresses Names are easier (for us!) to remember www.cnn.com vs. 64.236.16.20 IP addresses can change underneath Move www.cnn.com to 173.15.201.39 E.g., renumbering when changing providers Name could map to multiple IP addresses www.cnn.com to multiple replicas of the Web site Map to different addresses in different places Address of a nearby copy of the Web site E.g., to reduce latency, or return different content Multiple names for the same address E.g., aliases like ee.mit.edu and cs.mit.edu 5
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
CSE 486/586, Spring 2012 Two Kinds of Identifiers Host name (e.g., www.cnn.com ) Mnemonic name appreciated by humans Provides little (if any) information about location Hierarchical, variable # of alpha-numeric characters IP address (e.g., 64.236.16.20 ) Numerical address appreciated by routers Related to host’s current location in the topology Hierarchical name space of 32 bits 6
Background image of page 6
CSE 486/586, Spring 2012 Hierarchical Assignment Processes Host name: www.cse.
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 38

8- dns - CSE 486/586 Distributed Systems Domain Name System...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online