Hierarchical Routing Architecture Introduction draft-xu-rrg-hra-00.txt Routing Research Group

1. Hierarchical Routing Architecture Introduction draft-xu-rrg-hra-00.txt Routing Research Group Xiaohu XU (xuxh@huawei.com) Sheng JIANG (shengjiang@huawei.com)

2. Content • Background • Hierarchical Routing Architecture • HRA Overview • Hierarchical Routing Mechanism • Hierarchical Host Identifier Tag • ID/Locator Mapping System • Benefits • Future Work and Open Issues

3. Background • Routing growth threats • More CPU, More TCAM • More power consumption • CapEx and OpEx rise • Main causes: • Multi-homing • Traffic-engineering • PI address

4. Background • Underlying reason for routing growth • Dual role of IP address • ID/Locator split is a basic idea to solve this issue • Virtual ID between communication entities, eg. shim6 • Crypto host ID, eg.HIP • EID/RLOC split, eg.LISP • EID/AS split, eg.ENCAPS, HLP Identifier Locator

5. Hierarchical Routing Architecture Overview • One of ID/Locator split solutions • Hierarchical routing mechanism • Independent Locator Domain (LD), Each locator domain has a global unique LDID • Support multiple independent address spaces • A combination of LDID and local locator is a global unique locator • Hierarchical Host Identifier Tag • A combination of a management domain ID and a hash value of Host Identifier (public key) • Hierarchical mapping system • Mapping services between Host Identifier Tags and locators • Using HIT as the lookup key

6. Hierarchical Routing Mechanism LD 4 R2 R3 R4 LD 1 LD 2 LD 5 R5 R6 R1 LD 3 R7 • 2-level hierarchical routing • Inter-LD routing and intra-LD routing • Locator Domain Border Routers (LDBRs) exchange LD reachability information • LDBRs only store LD-ID based routing information • Internal routers support prefix-based routing • Internal routers only store internal routing information

7. Example1: Routing within the same LD LD ID + local locator = global unique locator LD 4 R2 R4 R3 LD 1 LD 2 LD 3 LD 5 R5 R6 R1 Host A R7 IPv4 Routing Host B

8. Example2: Routing between different LDs LD ID + local locator = global unique locator LD 4 Host B R2 R4 R3 LD 1 LD 2 LD 5 R5 R6 R1 LD 3 APP Host A R7 HIT A LD 3 + IPv4 A Host BHITLD4+IPv6 B

9. Host Identifier Tag • Flat Host Identifier Tag • Used in HIP and Node ID Architecture • Has scalability issues • Hard to manage • No guarantee for global uniqueness • Low-efficient lookup • Hierarchical Host Identifier Tag • A combination of a Management Domain ID (MDID) and a hash value of HI • Ease of management • Feasible and deployable mapping system with high lookup efficiency

10. ID/Locator Mapping System • Hierarchical mapping system • Each Management Domain (which may be covered several Locator Domain) has at least one local mapping server • Each server stores local HIT->Locator mapping info • Servers store MDID->Remote LDID mapping • Lookup requests for the same MDID, can find in the local database • Lookup requests for different MDIDs are forwarded to Remote Locator Domain and served by its default mapping server LD 4 MD b R2 R3 R4 LD 1 LD 2 LD 5 R5 R6 R1 LD 3 R7 LD5+IPv6 B MDID b LD5 HIT B

11. Benefits • The routing table size in each router will be greatly reduced • Routing stability will be improved • Reusable locator address space • Support communication between heterogeneous networks • Management of the global HIT namespace becomes more practical

12. Future Work and Open Issues • LD management issue (merge and split) • Routing policy • Incremental deployment • More details to be confirmed

13. Comments are welcomed! Thank You!