ISP Mapping                      (Rocketfuel)                              Simon WadsworthBased on ”Measuring ISP Topologi...
Why map ISPs?    ●   Real topologies not public    ●   Want to see router level conectivity and POP          structure    ...
An ISP    ●   ISP consists of a bunch of POPs connected by a           ”backbone”    ●   Routers connected to backbone lin...
Selecting Measurements    ●   Only need to take traceroutes expected to transit          ISP    ●   Only need to take one ...
Directed Probing    ●   Identify traceroutes that transit ISP    ●   Dependent prefixes           ●   Prefixes originated ...
Directed Probing    ●   Up/down traces           ●   Likely to transit ISP based on AS­path                               ...
Path Reductions    ●   Ingress Reduction           ●   Two traceroutes from different vantage points to                 sa...
Alias Resolution    ●   Found Mercator was efficient, but missed many          aliases    ●   Created Ally, the IP­ID base...
Router Identification    ●   DNS           ●   Geographical Location           ●   Role in topology    ●   s1­bb11­nyc­3­0...
Rocketfuel              
Rocketfuel    ●   Egress Discovery           ●   Find the egress routers, traceroute to each dependent                  pr...
Rocketfuel    ●   Path Reductions           ●   Take tasklist, apply ingress and next­hop AS                 reductions an...
Evaluation    ●   Asked ISPs to validate results – Three ISPs assisted           ●   ISPs said they didnt miss any POPs   ...
Evaluation    ●   Comparison with RouteViews           ●   Check number of adjacencies seen in maps compared              ...
Impact of Reductions    ●   Reduced number of traces down to 0.1% of those          required by a brute­force technique   ...
Questions         
Upcoming SlideShare
Loading in …5
×

ISP Mapping

1,054 views

Published on

Presentation given regarding ISP Mapping, based on a paper which presents Rocketfuel by Spring et al.

Published in: Technology
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
1,054
On SlideShare
0
From Embeds
0
Number of Embeds
3
Actions
Shares
0
Downloads
10
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

ISP Mapping

  1. 1. ISP Mapping (Rocketfuel) Simon WadsworthBased on ”Measuring ISP Topologies with Rocketfuel” by Spring et al.    
  2. 2. Why map ISPs? ● Real topologies not public ● Want to see router level conectivity and POP  structure   
  3. 3. An ISP ● ISP consists of a bunch of POPs connected by a  ”backbone” ● Routers connected to backbone links are  ”backbone” or ”core” routers ● Every POP has access routers providing layer  between ISP backbone  and neighboring networks   
  4. 4. Selecting Measurements ● Only need to take traceroutes expected to transit  ISP ● Only need to take one traceroute when two or more  enter and leave the ISP at the same point ● So make use of Directed Probing and Path  Reductions   
  5. 5. Directed Probing ● Identify traceroutes that transit ISP ● Dependent prefixes ● Prefixes originated by the ISP or single­homed  customers ● All traceroutes to prefix should transit ISP ● Identified from BGP table ● Insiders ● From traceroute server in a dependent prefix   
  6. 6. Directed Probing ● Up/down traces ● Likely to transit ISP based on AS­path   
  7. 7. Path Reductions ● Ingress Reduction ● Two traceroutes from different vantage points to  same destination enter at same point ● Egress Reduction ● Traceroutes from same ingress to any prefix behind  same egress witll be same path ● Next­hop AS Reduction ● Path depends on next­hop AS ● Only one race from ingress router to next­hop AS  is valuable  
  8. 8. Alias Resolution ● Found Mercator was efficient, but missed many  aliases ● Created Ally, the IP­ID based method of Alias  Resolution ● It finds 3x as many Aliases as previous methods   
  9. 9. Router Identification ● DNS ● Geographical Location ● Role in topology ● s1­bb11­nyc­3­0.sprintlink.net ● Sprint Backbone Router ● P4­0­0­0.r01.miamifl01.us.bb.verio.net ● Verio Backbone router   
  10. 10. Rocketfuel   
  11. 11. Rocketfuel ● Egress Discovery ● Find the egress routers, traceroute to each dependent  prefix from a local machine ● Dependent prefixes may be aggregated ● Break them into /24s ● Tasklist Generation ● Use BGP tables to generate list of directed probes ● Dependent prefixes in directed probes replaced with  egresses, and duplicates removed   
  12. 12. Rocketfuel ● Path Reductions ● Take tasklist, apply ingress and next­hop AS  reductions and generate jobs ● Checks if predicted ingress or egress was used, then  job is complete, otherwise other vantage point is  chosen ● Execution Engine ● Handles load­limiting, load balancing and different  formats of traceroute output   
  13. 13. Evaluation ● Asked ISPs to validate results – Three ISPs assisted ● ISPs said they didnt miss any POPs ● ISPs said they didnt miss any links between POPs ● Missed some access routers ● Received a Good, Very good and Vgood to Excellent  rating from the ISPs ● IP address space ● Scans 60 /24s looking for new routers ● They found that they found approximately 48.6 to  78.9% of the routers   
  14. 14. Evaluation ● Comparison with RouteViews ● Check number of adjacencies seen in maps compared  to RouteViews ● Router­level map should include one link from a  router to one in neighboring AS ● Worst case was 70% ● Comparison with Skitter ● Found 7x as many routers, links and IPs by Skitter   
  15. 15. Impact of Reductions ● Reduced number of traces down to 0.1% of those  required by a brute­force technique ● Scales well with number of vantage points   
  16. 16. Questions   

×