Floodless in SEATTLE : A Scalable Ethernet ArchiTecTure for Large Enterprises.

1. Floodless in SEATTLE : A Scalable Ethernet ArchiTecTure for Large Enterprises. Changhoon Kim, Matthew Caesar and JeniferRexford. Princeton University 2009, 3rd March Presented by Chervet Benjamin Animation on page 9, 14, 15 and 16 come fromChanghoonKim’s presentation.

2. Motivation • Networks are getting larger • Up to 25 000 hosts and 1 000 switchs for large enterprises Networks. • Larger and larger datacenter at Google, Yahoo or Microsoft for the largest ones. • Everyone in a University has access to the Internet.

3. Motivation (2) Networks are gettinglarger Hard to keep efficient, recquires networks administrators and operators. More money isspent on maintenance thanimproving the Network with new materials. Need to find out where the problemsis and how to solveit.

4. Outline • Find where the problem is : Current Networks • Ethernet Network • Hybrid (Ethernet/IP) Network • Comparison Ethernet/IP • Solve the problem : Seattle architecture • Objectives • Solutions offered • Evaluate the solutions : • Simulation results • Experimental results • Conclusion • Benefits • Lessons Learned

5. Current Networks • Ethernet Network • Heavily rely on broadcast to know where a host is (ARP, DHCP) • - large use of bandwidth, • - privacy concerns • + learn automatically the address, • + ensure mobility of a machine • -Flat addressing : Switch maintains a table associating all the Mac Address of the Network with its output ports. • -can lead to very large table • Build a spanning tree • + No loops in the Network • - links unused • - uneven loads

6. Actual Networks • Ethernet Network • Simple Network management • Low operating costs • Support host mobility • The bigger the network is the less efficient it is • Ethernet does not scale

7. Actual Networks • Hybrid IP/Ethernet Networks LAN Machine sharing the same subnets. The subnet are interconnect by IP Networks. -The broadcast stay in a subnet. + No flood on the entire Network. - Manual configuration needed. - No mobility possible. -Routing done though OSPF + Efficient use of links + No loops LAN IP Network LAN

8. Actual Networks • Hybrid IP/Ethernet Network • Can accommodate very large Networks • Efficient routing • No self configuration possibility • No mobility support • Complex to manage

9. Comparaisons

10. Comparaisons • SEATTLE : • Get the best of Ethernet and IP. • Configuration free (like Ethernet) and Scalable (as IP).

11. Seattle architecture • Objectives • Avoid flooding • Send a message only to the receiver • Never broadcast unicast traffic • Limits broadcasting • Directory service • Keep forwarding tables small • Host location should be kept only where it is needed • Distribution of the data.

12. Seattle architecture • Objectives (2) • Path efficient. • Need a routing protocol • Switch can learn the topology • Backward compatible • Compatible with IP and Ethernet Network • Does not modify end-hosts view

13. Seattle architecture • Solution offered : • Network layer one hop DHT All the Switch implement a hash function F, associating <key, value> pair. - For every key F returns the same value. - F returns one of the switch from a key. - Each Switch must know about all the other living switch. Cache system is used :the switch cache some frequently used information Smart cache update implemented : retrieves the information by surveying the traffic.

14. How does it works ? Optimized forwarding directly from D to A y Deliver to x x C Host discovery or registration Traffic to x A Tunnel to egress node, A Hash(F(x) = B) Tunnel to relay switch, B Hash (F(x) = B) D Entire enterprise (A large single IP subnet) LS core Notifying<x, A> to D B Store<x, A> atB E Switches End-hosts Control flow Data flow

15. < x, G > < x, G > < x, G > Response to host mobility Old Dst Src < x, A > x y when shortest-path forwarding is used A D < x, A > Relay (for x) G B New Dst < x, G > < x, A >

16. SEATTLE Architecture • Handling ARP requests 4. BroadcastARP reqfor a b sb Owner of (IPa ,maca) a 5. HashingF(IPa) = ra sa 1. Host discovery 6. UnicastARP reqto ra 2. Hashing F(IPa) = ra 7. Unicast ARP reply(IPa , maca ,sa)to ingress Switch ra End-host 3. Storing (IPa ,maca ,sa) Control msgs ARP msgs

17. Evaluation of the solutions • We want to know if the new solutions performs better than current networks ? • Simulation using a packet simulator • 4 different topologies • Campus network (517 routers and switches) • AP-small (87 routers) • AP-large (315 routers) • DC (Data center network)

18. Stretch: Path Optimality Stretch = Current path length / Shortest path length

19. Control messages

20. Size of the tables

21. Experimentation on Emulab • Emulab: similar to planetLab: set of PC around the world. • Useful to test real world networks with some practical values for latency and bandwidth • In this experimentation: 10 PC Free BSD Nodes

22. Number of messages exchanged

23. Conclusions: • Benefits : • Reduce the flow of data exchanged by order of magnitude • Fast and efficient reaction to changes • Reliability and capacity grows with the size of Network • Less man-made configuration needed Plug and Playable Networking ensuring efficiency and scalability.

24. Conclusions • Lessons learned • A new protocols has been created by combining different technologies from different background. • DHT Based routing used first in P2P technologies. • Link state routing • Caching