Routing Support for Wide Area Network Mobility. Z. Morley Mao Associate Professor Computer Science and Engineering University of Michigan

Transcription

1 Routing Support for Wide Area Network Mobility Z. Morley Mao Associate Professor Computer Science and Engineering University of Michigan 1

2 Outline Introduction Inter-AS Mobility Support Intra-AS Mobility Support Evaluation Conclusion 2

3 Introduction The ability to access Internet anywhere anytime becomes important Increasing commute time and mobility People spend more time on move People expect seamless data session Transportation systems are increasingly fitted with data connectivity (mobile networks) Less safety hazard Increase productivity 3

4 IP Network Mobility Reliability Low latency Seamless session ISP1 ISP2 4

5 Motivation Challenges Network moves Change of attachment point Change of service provider Disruption of Applications NEMO (Network Mobility) Extension of mobile IP Depends on public home agent Triangular routing Gogo Inflight Internet Connect to cell towers on land Transparent roaming across cell towers Boeing Connexion (defunct) Leverage BGP to achieve efficient routing Scalability concerns (may lead to routing instability) Address only mobility across ASes 5

6 WINMO (Wide-area IP Network Mobility) Support wide area Internet network mobility Inter-AS mobility Intra-AS mobility Goal Minimum routing overhead when moving across attachment points Minimum path inflation Location privacy protection Substantially reduced impact of DoS attacks 6

7 Design decisions Global Network Infrastructure Mobile networks roam mostly within an AS but may switch to another AS occasionally Infrastructure support Mobile ISP (MISP) End-host support Transparent to mobile client Incrementally deployable Security association AAA server in MISP No security association between end hosts 7

8 Architecture 8

9 Inter-AS Mobility Support (Connexion) Internet withdraw /24 Announce /24 MISP 1 MISP 2 Prefix: /24 Significant increase in: BGP table size # of BGP updates Routing instability Temporal loss of routes 9 Performance degradation

10 Limit propagation of BGP updates Techniques used in WINMO Mobile prefixes Aggregation routers Mobility community Scoped BGP updates Tunnel mapping Goal Reduce # of AS that need to keep routing states Allow aggregation of the routing states of multiple MNs Reduce # of routers in an AS that need to keep routing states 10

11 Details Mobile Prefixes (MPs) Each tier-1 ISP designates a large prefix as its Mobile prefix An ISP can allocate sub-prefixes to its customer Sub-prefixes may scattered all across the Internet Aggregation Routers (AR) and Mobility Community AR: a set of routers in tier-1 ISP that advertise root MPs Only AR keeps routing states for all mobile networks Non-ARs have a routing entry for each root MP default to its closest AR New BGP community attribute: Mobility Community Guarantee that BGP updates for MPs only propagate among ARs 11

12 Scoped BGP Updates Provider link Customer link Provider AS Peering link Peer AS Customer AS Customer link MISP 1 MISP 2 Propagation of BGP updates for /24 Prefix: /24 Without scoped BGP updates Large number of updates All ASes keep routing states 12

13 Scoped BGP Updates Provider link Customer link Provider AS Peering link Peer AS Customer AS MISP 1 Already Create has an an entry for MP in in Routing table Customer link MISP 2 Propagation of BGP updates for /24 (with mobile community) Prefix: /24 BGP Suppress updates the BGP of MPs updates doesn t in propagate the common to provider customers or nontier1 peers 13

14 Tunnel Mapping Prefix TE Source /24 AR2 Mapping / BGP Prefix TE Source / BGP ISP1 ISP2 Mapping Advertise for /24 Announce / /16 is the mobility prefix for ISP1 A subprefix /24 is attached to CE /24 14

15 Intra-AS Mobility Support Infrastructure support Designated BGP router (DBR) Mobile networks update DBR of its Care-ofaddress Packet Mobility Sate Remove triangular routing Guarantee of location privacy Prevention of DoS to the mobile networks 15

16 Packet Mobility State (MOS) Encode the binding between home prefix (HoP) and visiting care-of-address (CoA) using the current mobility router group key: Updated when mobile network switch to a new base station Authenticated by AAA to prevent bogus base station Binding is encrypted for location privacy and integrity MOS is stamped by base station into IP packets (as IP option or a shim layer) A correspondent host (CH) bounces the opaque token back (i.e. attach to the reply packets) 16

17 Intra-AS Mobility Internet Authenticate MOS and Get COA Data packet + Reply packet + CH Data packet + Data packet MISP CH always use home address to communicate with mobile host Prefix: /24 17

18 Intra-AS Mobility Authenticate MOS and Get COA 2 Reply packet + Internet CH Data packet + Data packet + MISP Data packet CH always use home address to communicate with mobile host Prefix: /24 18

19 WIMO Properties Global reachability Routing optimality Security and Privacy Resilience to DDoS attack Preservation of location privacy 19

20 Evaluation Settings SSFNet Simulation based on real Internet topology Inter-AS topology Infer AS relationship from RouteViews AS selects routes based on business relation # AS # edges # customer provider links # peering links # sibling 23,408 56,002 44,482 11, Intra-AS topology POP-level topologies of 5 ISPs from Rocketfuel data Annotate each link with approximate delay 20

21 Inter-domain mobility support Tradeoff Path inflation vs. BGP update amounts Path inflation Compare against NEMO and Connexion Connexion removes triangular routing Avg. Path Length Avg. Path Length Ratio Connexion NEMO WINMO

22 Inter-domain mobility support Routing dynamics Number of BGP updates Disruption time: time duration when a router doesn t have a route to reach the mobile prefix 22

23 Intra-AS mobility support A mobile network roams within an AS Path/delay inflation of NEMO normalized by WINMO ISP Telstra Tiscali Sprintlink Ebone Exodus # POPs Avg path inflation Avg delay inflation

24 Conclusion We propsed WINMO, a systematic solution for wide area IP network mobility Low routing overhead for mobile networks roaming across wide area Minimum path inflation for mobile networks roaming within the same AS Protection of location privacy and DoS attack Future work: scaling to a larger number of mobile prefixes 24

25 Thank you Any questions? 25