1. CIS 700-5: The Design and Implementation of Cloud Networks
Vincent Liu
Spring 2017
Includes material from lectures by Mohammad Alizadeh, George Porter, and Jennifer Rexford

2. Cloud Computing is Everywhere

3. Cloud Computing is Everywhere

4. What is Cloud Computing?
Client
Server

5. What is Cloud Computing?
Client
Server

6. Cloud Computing Benefits
Elastic
Scale up & down based on demand
Multi-tenancy
Multiple independent users share infrastructure
Security and resource isolation
SLAs on performance & reliability (sometimes)
Dynamic Management
Resiliency: isolate failure of servers and storage
Workload movement: move work to other locations

7. Cloud Service Models Software as a Service Platform as a Service
Provider licenses applications to users as a service
E.g., customer relationship management, , ..
Avoid costs of installation, maintenance, patches, …
Platform as a Service
Provider offers platform for building applications
E.g., Google’s App-Engine
Avoid worrying about scalability of platform

8. Cloud Service Models Infrastructure as a Service
Provider offers raw computing, storage, and network
E.g., Amazon’s Elastic Computing Cloud (EC2)
Avoid buying servers and estimating resource needs

9. Enabling Technology: Virtualization
Multiple virtual machines on one physical machine
Applications run unmodified as on real machine
VM can migrate from one computer to another

10. Virtual Switch in Server

11. The Result: Data Centers
Microsoft
Microsoft
Google
Facebook

12. Data Centers Are Big 10-100K servers 100s of Petabytes of storage
100s of Terabits/s of Bw (more than core of Internet)
10-100MW of power
(1-2 % of global energy consumption)
100s of millions of dollars
100 billion searches per month
1.15 billion users
120+ million users

13. Data Center Traffic Growth
Source: “Jupiter Rising: A Decade of Clos Topologies and Centralized Control in Google’s Datacenter Network”, SIGCOMM 2015.

14. How to Build a Cloud Network

15. There’s a lot of ground to cover!

16. How to Build a Cloud Network
Data Center Network
Lets start small

17. How to Build a Cloud Network
Data Center Network
In fact, let’s go even smaller
Part 1: Physical Layer

18. Servers in Racks Rack of servers Modular design Commodity servers
And top-of-rack switch
Modular design
Preconfigured racks
Power, network, and storage cabling

19. Racks in Rows

20. Rows in Hot/Cold Pairs

21. Hot/Cold Pairs in Data Centers
That’s a DC. Upward of a million square feet

22. The Data Center Network (Logical)
*From Al-Fares et al.
SIGCOMM ‘08

23. The Data Center Network (Physical)

24. How to Build a Cloud Network
Data Center Network
In fact, let’s go even smaller
Part 2: All The Other Layers

25. The OSI Model 7. Application 4. Transport 3. Network 2. Data Link
Reliable streams OR messages
3. Network
Best effort global packet delivery
2. Data Link
Best effort local packet delivery
1. Physical
How to send bits from A to B

26. The OSI Model 7. Application 4. Transport 3. Network 2. Data Link
TCP/UDP
3. Network IP
2. Data Link
Ethernet
1. Physical
Copper and optical links

27. Layer 2: Ethernet Not scalable
MAC address (e.g., C A9 from Dell)
Numerical address used within a link
Unique, hard-coded in the adapter when it is built
Flat name space of 48 bits
Single shared broadcast channel
Not scalable

28. Layer 3: IP IP addresses Hop-by-hop packet routing
Addresses are assigned and can be changed
Hierarchical addressing, as opposed to flat
Hop-by-hop packet routing
Each router has a forwarding table
Maps destination address to outgoing interface
Upon receiving a packet
Inspect the destination address in the header
Index into the table
Determine the outgoing interface
Forward the packet out that interface
Then, the next router in the path repeats

29. Layer 4: User Datagram Protocol (UDP)
Datagram messaging service
Demultiplexing: port numbers
Detecting corruption: checksum
Lightweight communication between processes
Send and receive messages
Avoid overhead of ordered, reliable delivery
SRC port
DST port
checksum
length
DATA

30. Layer 4: Transmission Control Protocol (TCP)
Stream-of-bytes service
Sends and receives a stream of bytes
Reliable, in-order delivery
Corruption: checksums
Detect loss/reordering: sequence numbers
Reliable delivery: acknowledgments and retransmissions
Connection oriented
Explicit set-up and tear- down of TCP connection
Flow control
Prevent overflow of the receiver’s buffer space
Congestion control
Adapt to network congestion for the greater good