How To Make A Route Map On Bpg More Efficient

Transcription

1 NIRA: A New Inter-Domain Routing Architecture Xiaowei Yang, David Clark, Arthur W. Berger Rachit Agarwal (Results are by others, any errors are by me) ( Animated slides shamelessly stolen from Prasad s slides (CS495, Northwestern University), Thanks Google!)

2 What this paper talks about! Routing at domain level Giving more control to the user over the route Fosters competition among ISPs Routes chosen by BGP not the most efficient Only users know whether a path suits his/her application

3 What this paper talks about! Claims to answer the questions: Supporting user choice provider compensation scalable route discovery efficient route representation fast route fail-over security

4 What this paper does not talk about! Acknowledged Issues: Autonomy Issues (why would an ISP allow that?) Potential performance problems Issues not acknowledged: Where is design for tussle? (stronger users means stronger attacks?)

5 NIRA

6 Core tier-i ISPs: ISPs that have no providers Core: Region where tier-i ISPs interconnect Up-graph (of an user): network of user s providers, provider s providers (and peers) until the core is reached

7 Example: Core Cindy R8 B4 B1 core R7 B3 B2 N9 N18 R1 R2 R3 Bob N1 N2 N3 Alice

8 NIRA in a nutshell! Every node gets a path from its up-graph to the core All these paths get stored in a DNS-like database (NRLS) Path Selection: Choose your up-graph as part of the route Query name-to-route look-up service (NRLS) for destination s up-graph Combine the two to get a path to the destination User s route not selected by the user, but by both user and destination!

9 Example: NIRA in a nutshell! N15 N16 N17 N18 N14 N13 N12 N11 N10 N9 R9 R8 R7 R6 R10 R1 B4 B1 core R2 B3 B2 R5 R4 R3 Bob N1 N2 N3 Cindy N8 N7 N6 N5 N4 Alice

10 Some Interesting Details Addressing

11 Addressing Hierarchical address assignment Providers in the Core obtain a globally unique address prefix Provider then allocates non-overlapping subdivisions of the address prefix to each of its customers Discussion: Practical addressing scheme? One can infer ISP relationships!

12 Bob 1:1:1::/48 1:2:1::/48 R1 Example: Addressing Core 1::/16 2::/16 1:1::/32 1:2::/32 B2 R3 1:3::/32 2:1::/32 1:2:2::/48 N1 N2 N3 1:1:1::1000 1:2:1::1000 B1 R2 1:3:1::2000 2:1:1::2000 1:3:1::/48 2:1:1::/48 Alice Note: An address represents a valid route to the core.

13 Forwarding Tables Uphill table 1::/16 B1 Downhill table 1:1:1::/48 N1 1:1::/96 self Core 1::/16 2::/16 1:1::/32 1:2::/32 1:1:1::/48 1:2:1::/48 Bob R1 B1 R2 B2 R3 1:3::/32 2:1::/32 1:2:2::/48 N1 N2 N3 1:1:1::1000 1:2:1::1000 1:3:1::2000 2:1:1::2000 1:3:1::/48 2:1:1::/48 Alice Uphill table: providers Downhill table: customers, self Bridge table: all others Scalability: Size of core limited (financial factors), Provider hierarchy is shallow (domains have limited number of providers)

14 Hierarchical Addresses Provider-rooted hierarchical address User can use a source and a destination address to compactly represent a valley-free route Switch routes by switching addresses Both source and destination addresses used for forwarding Limits source address spoofing Router may not find an address with an arbitrary source address

15 Efficient Route Representation

16 Example: Route Representation N15 N16 N17 N18 N14 N13 N12 N11 N10 N9 R9 R8 R7 R6 R10 R1 B4 B1 core R2 B3 B2 R5 R4 R3 Bob N1 N2 N3 Cindy N8 N7 N6 N5 N4 Alice

17 Efficient Route Representation Core 1::/16 2::/16 1:1::/32 1:2::/32 1:1:1::/48 1:2:1::/48 Bob R1 B2 R3 1:3::/32 2:1::/32 1:2:2::/48 N1 N2 N3 1:1:1::1000 1:2:1::1000 B1 R2 1:3:1::2000 2:1:1::2000 1:3:1::/48 2:1:1::/48 Alice A source and a destination address unambiguously represent a route.

18 Forwarding

19 Overview Packet first forwarded along the sequence of domains that allocate the source address Within the core (from source s provider to destination s provider) Finally, along the sequence of domains that allocate the destination address

20 up down 1:1:1::1000 1:3:1::2000 Forwarding Core 1::/16 2::/16 1:1::/32 1:2::/32 1:1:1::/48 1:2:1::/48 Bob R1 B1 R2 B2 R3 1:3::/32 2:1::/32 1:2:2::/48 N1 N2 N3 1:1:1::1000 1:2:1::1000 1:3:1::2000 2:1:1::2000 1:3:1::/48 2:1:1::/48 Alice Look up destination address in the downhill table. If no match: Look up the source address in the uphill table.

21 Discussion Scalability? Consider each ISP having two providers. An user at level k will have O(2 k ) paths. User control? How to exploit this control? How to measure goodness of a domain-level route? Security: Does stronger users necessarily mean stronger attacks? Mobility?

22 Back-up slides (TIPP and Route Failures)

23 Topology Information Propagation Protocol (TIPP) Path-vector component Propagating domain level routes Providers propagate routes to their customers, which in turn propagate routes to their customers No route selection (no policy-enforcement) Link-state component Information about dynamic network changes Link-state messages could potentially be propagated only down the hierarchy (no message from a customer to provider required)

24 Handling Route Failures

25 Route Failures Problem: TIPP messages do not propagate globally The sender might not have up-to-date information about destination s path (when the destination does not update its routes in NRLS very frequently) Solution: If the route in the packet header is unavailable, inform the sender! If no information received, use timeout!