2-Phased Mapping for Internet Core/Edge Split Scheme Wei Zhang Tsinghua University

Background RRG Tasks Next generation Internet routing architecture Focuses: Routing Concerns: Scalability problem Solutions: Hierarchical routing Core/Edge split (LISP,eFIT,IVIP,SIX/ONE...) Proposals: Common necessity: Mapping from Edge/EID to Core/RLoc Where we are going !

Motives Mapping from EID to RLoc in core/edge schemes may not be scalable if the dynamics of (prefix,ETR) binding is high. In order to make the routing system really scalable and reduce the overhead on updating, we need to design a relatively more stable mapping mechanism than any EID topology or routing policy changes.

A 2-phased mapping model Phase I Phase II Prefixes AS# ETRs An M:1:M mapping model Introduce AS# in the middle can prevent too much detailed topology/policy changing information from getting into the mapping system.

Assumptions all ASes know better their local prefixes (in the IGP) than others. ASes also know better their ETRs. So all mapping information can be collected locally.

Implements Phase I mapping system (register/resolve prefix to AS#) Each AS should have at least one agent to register its local prefixes (range of IP addresses). May be hierarchical like DNS, or centralized like whois. Phase II mapping (AS# to ETRs) XTRs advertise their AS# bindings with each other through BGP extension.

Deployments Core Phase I mapping servers Updated border routers (XTRs) Edge Register agents

Phase I Updating Internet Core Phase I mapping server Edge AS1 Prefix register agent Prefix register agent 1.1.0.0/17 1.1.128.0/17 2.2.0.0/16

Phase II Updating Internet Core BGP advertisement Edge AS1 Edge AS2 XTR3 XTR1 XTR2 AS1 has ETR1 AS2 has ETR2,ETR3 AS1 has ETR1 Edge AS1 Edge AS2 XTR=ITR/ETR

Phase I Lookup Internet Core Phase I mapping server Edge AS1 Edge AS2 Where is 2.2.2.2 2.2.2.2 in AS 2 AS1:ITR1 AS2:ETR3 AS2:ETR2 Edge AS1 Edge AS2 Host A 2.2.2.2

Phase II Lookup Internet Core Edge AS1 Edge AS2 Tunnel packets to ETR2 ITR1 will Check which ETR is the closest to AS2 AS2:ETR3 AS2:ETR2 Edge AS1 Edge AS2 Host A 2.2.2.2

Gains Any prefixes reconfiguration (aggregation/ deaggregation) within an AS will not be notified to mapping system. Possible highly efficient aggregation of the local prefixes (a range of IP space). Both phase I and phase II mapping can be stable. A stable mapping system will reduce the update overhead introduced by topology change/routing policy dynamics.

Summary The 2-phased mapping scheme introduces AS# between the mapping prefixes and ETRs. The decoupling of direct mapping makes highly dynamic updates stable, therefore it can be more scalable than any direct mapping designs. The 2-phased mapping scheme is adaptable to any core/edge split proposals.