Hierarchical Routing Architecture Introduction

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Hierarchical Routing Architecture
Introduction draft-xu-rrg-hra-00.txt Routing
Research Group Xiaohu XU (xuxh_at_huawei.com) Sheng
JIANG (shengjiang_at_huawei.com)
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Content

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

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Background

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

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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
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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

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Hierarchical Routing Mechanism

• 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

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Example1 Routing within the same LD
LD ID local locator global unique locator
LD 4
R2
R3
R4
LD 1
LD 2
LD 3
LD 5
R1
R5
R6
Host A
R7
IPv4 Routing
Host B
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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
R1
R5
R6
LD 3
APP
Host A
R7
HIT A
LD 3 IPv4 A
Host BHITLD4IPv6 B
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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

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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-gtLocator mapping
  info
• Servers store MDID-gtRemote 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
R1
R5
R6
LD 3
R7
LD5IPv6 B
MDID b
LD5
HIT B
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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

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Future Work and Open Issues

• LD management issue (merge and split)
• Routing policy
• Incremental deployment
• More details to be confirmed

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• Comments are welcomed!
• Thank You!