1 / 16

MULTI-PATH ROUTING

MULTI-PATH ROUTING. A packet by packet multi-path routing approach. OVERVIEW. Multi-path routing (Benefits / Problems) Multi-Path routing protocol Multi-Path routing Transport Protocol Per-hop Packet Distribution Simulation results. Multi Path Routing.

aislin
Télécharger la présentation

MULTI-PATH ROUTING

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. MULTI-PATH ROUTING A packet by packet multi-path routing approach Dennis Ippoliti 12/6/2004

  2. OVERVIEW • Multi-path routing (Benefits / Problems) • Multi-Path routing protocol • Multi-Path routing Transport Protocol • Per-hop Packet Distribution • Simulation results Dennis Ippoliti 12/6/2004

  3. Multi Path Routing • In a well connected network multiple paths exist With Multi-Path routing, traffic is diffused over several paths at the same time Typically, one path at a time is chosen and all traffic is sent over that path Dennis Ippoliti 12/6/2004

  4. Benefits of Multi-Path routing • Enables Load balancing implementations • Simplifies algorithms if single flows can take multiple paths • Increases throughput • Decreases delay • Takes advantage of considerable redundancy • 90% of all US Sprintlink POP pairs are connected by 4 or more paths • Increases Robustness to Eavesdropping • Attackers must sniff multiple links when traffic is diffused Dennis Ippoliti 12/6/2004

  5. Challenges in Multi-Path routing • Route Identification • Identifying available routes • Route Selection • Round Robin, Weighted Selection, Other • Metrics (Throughput / Delay / Drop rate) • Different subsets of routes will maximize/minimize different metrics • Leads to persistent packet re-sequencing • When multiple routes are used, the probability that packets are received out of sequence is high Dennis Ippoliti 12/6/2004

  6. Multi-Path Routing Algorithms • In a network G = (N, L) with N nodes and L links, MP Algorithms identify S(I,j) such that S(I,j) = the set of successor nodes to rout traffic from node I to node j. • Multi-path routing algorithms identify S(I,j) and rank order according to some minimum or maximum desired metric or combination of metrics Dennis Ippoliti 12/6/2004

  7. Multi-Path Routing Algorithms • Multi-Path Distance Vector (MPDV) • Multi-Path Link State (MPLS) • Enhanced Interior Gateway Routing Protocol Dennis Ippoliti 12/6/2004

  8. Multi-Path Transport Protocol • Multi-Path environment causes persistent packet reordering Dennis Ippoliti 12/6/2004

  9. Multi-Path Transport Protocols • TCP is not effective in this environment • TCP uses windowing for error and congestion control • When packets are received out of order, DUPACKS are generated • DUPACKS typically decrease window size by 50% • DUPACKS cause sender to enter Fast Retransmit • Persistent DUPACKS reduce throughput while increasing traffic load Dennis Ippoliti 12/6/2004

  10. Multi Path Transport Protocols • Eifel Algorithm • Uses time-stamp option to differentiate between transmissions and re-transmissions • Restores TCP congestion window to value prior to retransmit when packet received • DSACK • Uses DSACK option to communicate from receiver to sender • Dynamically manipulate dupthresh value • TCP Persistent Reordering • Ignores DUPACKS. Uses timers to identify packet loss Dennis Ippoliti 12/6/2004

  11. Route Selection • Round Robin and pure load balancing not effective • Do not take network conditions into consideration • Minimum Delay Routing • As delay increases, the proportion of traffic distributed to that rout decreases Dennis Ippoliti 12/6/2004

  12. A B A B 1 2 1 2 3 4 5 3 4 5 6 7 8 6 7 8 9 0 9 0 C D C D Route Selection • Minimum Delay Routing with dynamic service differentiation • In multi path routing, a greedy node can starve other nodes on the network Dennis Ippoliti 12/6/2004

  13. A B A B 1 2 1 2 3 4 5 3 4 5 6 7 8 6 7 8 9 0 9 0 C D C D Route Selection • I experimented with Minimum Delay Routing with dynamic service differentiation • Traffic that is on a primary route is given priority over traffic on a secondary route Dennis Ippoliti 12/6/2004

  14. Simulation Method • Developed Network Simulator software similar to the Click Router Platform • C++ objects represent Nodes and Links • Static Multi-Paths • RR, Load Balancing, and Minimum Delay Routing as Route Selection methods • TCP-PR as transport protocol Dennis Ippoliti 12/6/2004

  15. Results • TCP-PR 200% through-put over standard TCP • Round Robin, Load balancing, and Minimum delay route selection performed the same when link cost equal • Only Minimum Delay performed well when link cost was unequal • Dynamic service differentiation prevents starvation in the presence of greedy flows Dennis Ippoliti 12/6/2004

  16. TCP-PR QUESTIONS? Dennis Ippoliti 12/6/2004

More Related