An Analysis of Scaling Issues in MPLS-TE Core Networks
RFC 5439
Network Working Group S. Yasukawa
Request for Comments: 5439 NTT
Category: Informational A. Farrel
Old Dog Consulting
O. Komolafe
Cisco Systems
February 2009
An Analysis of Scaling Issues in MPLS-TE Core Networks
Status of This Memo
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not specify an Internet standard of any kind. Distribution of this
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Abstract
Traffic engineered Multiprotocol Label Switching (MPLS-TE) is
deployed in providers' core networks. As providers plan to grow
these networks, they need to understand whether existing protocols
and implementations can support the network sizes that they are
planning.
This document presents an analysis of some of the scaling concerns
for the number of Label Switching Paths (LSPs) in MPLS-TE core
networks, and examines the value of two techniques (LSP hierarchies
and multipoint-to-point LSPs) for improving scaling. The intention
is to motivate the development of appropriate deployment techniques
and protocol extensions to enable the application of MPLS-TE in large
networks.
This document only considers the question of achieving scalability
for the support of point-to-point MPLS-TE LSPs. Point-to-multipoint
MPLS-TE LSPs are for future study.
Yasukawa, et al. Informational [Page 1]
RFC 5439 Scaling in MPLS-TE February 2009
Table of Contents
1. Introduction ....................................................3
1.1. Overview ...................................................3
1.2. Glossary of Notation .......................................5
2. Issues of Concern for Scaling ...................................5
2.1. LSP State ..................................................5
2.2. Processing Overhead ........................................6
2.3. RSVP-TE Implications .......................................6
2.4. Management .................................................7
3. Network Topologies ..............................................8
3.1. The Snowflake Network Topology .............................9
3.2. The Ladder Network Topology ...............................11
3.3. Commercial Drivers for Selected Configurations ............14
3.4. Other Network Topologies ..................................15
4. Required Network Sizes .........................................16
4.1. Practical Numbers .........................................16
5. Scaling in Flat Networks .......................................16
5.1. Snowflake Networks ........................................17
5.2. Ladder Networks ...........................................18
6. Scaling Snowflake Networks with Forwarding Adjacencies .........22
6.1. Two-Layer Hierarchy .......................................22
6.1.1. Tuning the Network Topology to Suit the
Two-Layer Hierarchy ................................23
6.2. Alternative Two-Layer Hierarchy ...........................24
6.3. Three-Layer Hierarchy .....................................25
6.4. Issues with Hierarchical LSPs .............................26
7. Scaling Ladder Networks with Forwarding Adjacencies ............27
7.1. Two-Layer Hierarchy .......................................27
7.2. Three-Layer Hierarchy .....................................28
7.3. Issues with Hierarchical LSPs .............................29
8. Scaling Improvements through Multipoint-to-Point LSPs ..........30
8.1. Overview of MP2P LSPs .....................................30
8.2. LSP State: A Better Measure of Scalability ................31
8.3. Scaling Improvements for Snowflake Networks ...............32
8.3.1. Comparison with Other Scenarios ....................33
8.4. Scaling Improvements for Ladder Networks ..................34
8.4.1. Comparison with Other Scenarios ....................36
8.4.2. LSP State Compared with LSP Numbers ................37
8.5. Issues with MP2P LSPs .....................................37
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