1 GIRO: Geographically Informed Inter-domain Routing Ricardo Oliveira, Mohit Lad, Beichuan Zhang, Lixia Zhang

2 Internet and Autonomous Systems AT&T Sprint Verizon Autonomous System: a set of routers or networks under the same administration Border routers exchange routing updates via the Border Gateway Protocol (BGP) Reachability announced through the form of prefixes, i.e. chunks of IP addresses /24

3 ? rara rbrb rcrc Prefix P 1.Policy: costumers > peers > providers 2.Lowest AS hop count 3.… What problem we are solving BGP route selection: how to pick the best one?

4 One Example Router A sends packets to prefix P A has two ways to reach P: Both AS 577 and AS 3561 are peer links Following "lowest AS hop" rule: A sends packets to AS 577 P: AS 3561, AS 577 P: AS 577

5 Suboptimal route selection ! AS3561 AS577 AS6461 Seattle, WA Palo Alto, CA Chicago, IL A BGP path (~ 3600 miles) Shorter path (~700 miles) P

6

7 GIRO Design Goals Geographical information 1. Improve data delivery performance within established routing policies 2. Improve routing scalability by reducing the global routing table size

8 GIRO Design Approach Adding geographic information into –Routers –BGP routes –IP address When everything else being equal: select path with shortest distance Aggregate route announcements by ASes and locations

9 Adding geographic information Configure each BGP router with geographic location informaiton Define a new BGP "location" attribute to be associated with each AS hop e.g. using BGP communities Enables each router to calculate the total path length x inC, y inC C B A x outB, y outB x inB, y inB x outA, y outA x origin, y origin

10 GIRO Address Scheme ASNgeolocationSIDSubnet and host External component (G-prefix) Internal component Including ASN upfront in the address ensures that pkts are routed primarily based on policies Geolocation information serves as secondary hint Traffic slice (SID) divides the incoming traffic to the G-prefix, e.g. one SID per provider The internal component is not announced to other networks; it’s used to route pkts inside the origin network

11 D Prefix Aggregation in GIRO A E C B Los Angeles,CA San Francisco,CA Chicago,IL Toronto,CAN New York,NY SID=0 SID=1 G-prefixASPATH B.US.CAA B B.US.ILA D B B. CANA D B C.US.NY.NewYork.0A C C.US.NY.NewYork.1A D C

12 Egress Point Selection late R1 R6 R2 R3 R5 R7 R0 100|12 A B 50|5 30|3 90|10 early shortest-path |5 Geographic distance IGP weight late-exit R4

13 GIRO Decision Process StepDescription 1.Highest LocalPref 2. Shortest geographic distance w/ resolution  3.Lowest AS hop count 4.Lowest origin type 5.Early exit (take route of shortest IGP distance) Late-exit (take lowest MED route) Shortest-path (take routes of shortest geographic distance)

14 70% of paths are shorter using GIRO compared to BGP 20% of paths are reduced by more than 40% Evaluation: Inter-domain route selection Used a RocketFuel PoP level topology with 668 inter-AS links and 67 ISPs For simulations used  =124 miles (equivalent of one sec. delay on fiber)

15 Evaluation: GIRO aggregation Extracted prefixes from BGP tables from Jan 2007-March 2007 Mapped each prefix to a geographical location using Maxmind Geolite –Found mapping for ~80% of prefixes (~196K)

16 GIRO Aggregation Geographical aggregation: aggregate all the prefixes that originated from the same origin AS and the same geolocation –Do not aggregate prefixes with different AS paths! –Preserve BGP AS path diversity

17 Evaluation: GIRO Aggregation GIRO achieves a 75% table size reduction compared to BGP

18 Incremental deployment? We do not have this: ASNgeolocationSIDSubnet and host Would need IPv6 bits to fit it all in address field …

19 –Configure each BGP router with geographic location informaiton –Define a new BGP "location" attribute to be associated with each AS hop (by using communities) –Enables each router to calculate the total path length x inC, y inC C B A x outB, y outB x inB, y inB x outA, y outA x origin, y origin But we can do this!

20 Conclusion and future work Geolocation information can help improve path selection under routing policy constraints Embedding ASN and geographical information in IP address can help improve routing scalability through aggregation Exploring the possibility of utilizing geolocation in BGP routing, moving forward w/ an I-D very soon…

21 Questions?

22 Does shortest-path policy cost more locally? Comparison between early-exit, late-exit, and shortest-path policy Shortest-path policy can reduce global cost significantly without sacrificing much of local cost Global cost (geographical distance) Local cost

23

24 Internet and Autonomous Systems AT&T Sprint Verizon Autonomous System: a set of routers or networks under the same administration Border routers exchange routing updates via the Border Gateway Protocol (BGP) Reachability announced through the form of prefixes, i.e. chunks of IP addresses /24

25 Evaluation: GIRO Aggregation GIRO achieves a 75% table size reduction compared to BGP About 40% of GIRO entries resulted from topological aggregation 60% of entries resulted from geographical aggregation

26 Inremental deployment? Incremental deployability of GIRO: –Can embedd geographic info into BGP communities What information to include in routes: absolute location or relative distance? –ISPs want to disclose minimal info about their networks –Geolocation info can help in doing fault diagnosis GIRO can also help in: –Prefix hijacking: prefix ownership problem is solved; false link attacks can be mitigated –Source address spoofing, if border routers at origin net stamp (some) data pkts with their geolocation