RFC 3036 (rfc3036) - Page 2 of 132
LDP Specification
Alternative Format: Original Text Document
RFC 3036 LDP Specification January 2001
Table of Contents
1 LDP Overview ....................................... 5
1.1 LDP Peers .......................................... 6
1.2 LDP Message Exchange ............................... 6
1.3 LDP Message Structure .............................. 7
1.4 LDP Error Handling ................................. 7
1.5 LDP Extensibility and Future Compatibility ......... 7
1.6 Specification Language ............................. 7
2 LDP Operation ...................................... 8
2.1 FECs ............................................... 8
2.2 Label Spaces, Identifiers, Sessions and Transport .. 9
2.2.1 Label Spaces ....................................... 9
2.2.2 LDP Identifiers .................................... 10
2.2.3 LDP Sessions ....................................... 10
2.2.4 LDP Transport ...................................... 11
2.3 LDP Sessions between non-Directly Connected LSRs ... 11
2.4 LDP Discovery ..................................... 11
2.4.1 Basic Discovery Mechanism .......................... 12
2.4.2 Extended Discovery Mechanism ....................... 12
2.5 Establishing and Maintaining LDP Sessions .......... 13
2.5.1 LDP Session Establishment .......................... 13
2.5.2 Transport Connection Establishment ................. 13
2.5.3 Session Initialization ............................. 14
2.5.4 Initialization State Machine ....................... 17
2.5.5 Maintaining Hello Adjacencies ...................... 20
2.5.6 Maintaining LDP Sessions ........................... 20
2.6 Label Distribution and Management .................. 21
2.6.1 Label Distribution Control Mode .................... 21
2.6.1.1 Independent Label Distribution Control ............. 21
2.6.1.2 Ordered Label Distribution Control ................. 21
2.6.2 Label Retention Mode ............................... 22
2.6.2.1 Conservative Label Retention Mode .................. 22
2.6.2.2 Liberal Label Retention Mode ....................... 22
2.6.3 Label Advertisement Mode ........................... 23
2.7 LDP Identifiers and Next Hop Addresses ............. 23
2.8 Loop Detection ..................................... 24
2.8.1 Label Request Message .............................. 24
2.8.2 Label Mapping Message .............................. 26
2.8.3 Discussion ......................................... 27
2.9 Authenticity and Integrity of LDP Messages ......... 28
2.9.1 TCP MD5 Signature Option ........................... 28
2.9.2 LDP Use of TCP MD5 Signature Option ................ 30
2.10 Label Distribution for Explicitly Routed LSPs ...... 30
3 Protocol Specification ............................. 31
3.1 LDP PDUs ........................................... 31
3.2 LDP Procedures ..................................... 32
3.3 Type-Length-Value Encoding ......................... 32
Andersson, et al. Standards Track
