wimaxing 2008-6-28 18:51
RFC5036-LDP Specification
【资料成文时间】： 2007
【语言】：英文
【页数】：135
【何人（公司）所著】：
【文件格式】： PDF
【文件原名】：LDP Specification
【摘要或目录】：
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 .....................................9
2.2.3. LDP Sessions .......................................10
2.2.4. LDP Transport ......................................10
2.3. LDP Sessions between Non-Directly Connected LSRs ..........10
2.4. LDP Discovery .............................................11
2.4.1. Basic Discovery Mechanism ..........................11
2.4.2. Extended Discovery Mechanism .......................11
2.5. Establishing and Maintaining LDP Sessions .................12
2.5.1. LDP Session Establishment ..........................12
2.5.2. Transport Connection Establishment .................12
2.5.3. Session Initialization .............................14
2.5.4. Initialization State Machine .......................16
2.5.5. Maintaining Hello Adjacencies ......................19
2.5.6. Maintaining LDP Sessions ...........................19
2.6. Label Distribution and Management .........................20
2.6.1. Label Distribution Control Mode ....................20
2.6.1.1. Independent Label Distribution Control ....20
2.6.1.2. Ordered Label Distribution Control ........20
2.6.2. Label Retention Mode ...............................21
2.6.2.1. Conservative Label Retention Mode .........21
2.6.2.2. Liberal Label Retention Mode ..............21
2.6.3. Label Advertisement Mode ...........................22
2.7. LDP Identifiers and Next Hop Addresses ....................22
2.8. Loop Detection ............................................23
2.8.1. Label Request Message ..............................23
2.8.2. Label Mapping Message ..............................25
2.8.3. Discussion .........................................26
2.9. Authenticity and Integrity of LDP Messages ................27
2.9.1. TCP MD5 Signature Option ...........................27
2.9.2. LDP Use of TCP MD5 Signature Option ................29
2.10. Label Distribution for Explicitly Routed LSPs ............29
3. Protocol Specification .........................................30
3.1. LDP PDUs ..................................................30
3.2. LDP Procedures ............................................31
3.3. Type-Length-Value Encoding ................................31
3.4. TLV Encodings for Commonly Used Parameters ................33
3.4.1. FEC TLV ............................................33
3.4.1.1. FEC Procedures ............................35
3.4.2. Label TLVs .........................................35
3.4.2.1. Generic Label TLV .........................36
3.4.2.2. ATM Label TLV .............................36
3.4.2.3. Frame Relay Label TLV .....................37
3.4.3. Address List TLV ...................................38
3.4.4. Hop Count TLV ......................................39
3.4.4.1. Hop Count Procedures ......................39
3.4.5. Path Vector TLV ....................................41
3.4.5.1. Path Vector Procedures ....................41
3.4.5.1.1. Label Request Path Vector ......41
3.4.5.1.2. Label Mapping Path Vector ......42
3.4.6. Status TLV .........................................43
3.5. LDP Messages ..............................................44
3.5.1. Notification Message ...............................46
3.5.1.1. Notification Message Procedures ...........48
3.5.1.2. Events Signaled by Notification Messages ..48
3.5.1.2.1. Malformed PDU or Message .......48
3.5.1.2.2. Unknown or Malformed TLV .......49
3.5.1.2.3. Session KeepAlive Timer
Expiration .....................50
3.5.1.2.4. Unilateral Session Shutdown ....50
3.5.1.2.5. Initialization Message Events ..50
3.5.1.2.6. Events Resulting from
Other Messages .................50
3.5.1.2.7. Internal Errors ................51
3.5.1.2.8. Miscellaneous Events ...........51
3.5.2. Hello Message ......................................51
3.5.2.1. Hello Message Procedures ..................53
3.5.3. Initialization Message .............................54
3.5.3.1. Initialization Message Procedures .........63
3.5.4. KeepAlive Message ..................................63
3.5.4.1. KeepAlive Message Procedures ..............63
3.5.5. Address Message ....................................64
3.5.5.1. Address Message Procedures ................64
3.5.6. Address Withdraw Message ...........................65
3.5.6.1. Address Withdraw Message Procedures .......66
3.5.7. Label Mapping Message ..............................66
3.5.7.1. Label Mapping Message Procedures ..........67
3.5.7.1.1. Independent Control Mapping ....67
3.5.7.1.2. Ordered Control Mapping ........68
3.5.7.1.3. Downstream on Demand
Label Advertisement ............68
3.5.7.1.4. Downstream Unsolicited
Label Advertisement ............69
3.5.8. Label Request Message ..............................70
3.5.8.1. Label Request Message Procedures ..........71
3.5.9. Label Abort Request Message ........................72
3.5.9.1. Label Abort Request Message Procedures ....73
3.5.10. Label Withdraw Message ............................74
3.5.10.1. Label Withdraw Message Procedures ........75
3.5.11. Label Release Message .............................76
3.5.11.1. Label Release Message Procedures .........77
3.6. Messages and TLVs for Extensibility .......................78
3.6.1. LDP Vendor-Private Extensions ......................78
3.6.1.1. LDP Vendor-Private TLVs ...................78
3.6.1.2. LDP Vendor-Private Messages ...............80
3.6.2. LDP Experimental Extensions ........................81
3.7. Message Summary ...........................................81
3.8. TLV Summary ...............................................82
3.9. Status Code Summary .......................................83
3.10. Well-Known Numbers .......................................84
3.10.1. UDP and TCP Ports .................................84
3.10.2. Implicit NULL Label ...............................84
4. IANA Considerations ............................................84
4.1. Message Type Name Space ...................................84
4.2. TLV Type Name Space .......................................85
4.3. FEC Type Name Space .......................................85
4.4. Status Code Name Space ....................................86
4.5. Experiment ID Name Space ..................................86
5. Security Considerations ........................................86
5.1. Spoofing ..................................................86
5.2. Privacy ...................................................87
5.3. Denial of Service .........................................88
6. Areas for Future Study .........................................89
7. Changes from RFC 3036 ..........................................90
8. Acknowledgments ................................................93
9. References .....................................................93
9.1. Normative References ......................................93
9.2. Informative References ....................................94
Appendix A. LDP Label Distribution Procedures ....................95
A.1. Handling Label Distribution Events .......................97
A.1.1. Receive Label Request .............................98
A.1.2. Receive Label Mapping ...........................101
A.1.3. Receive Label Abort Request .....................107
A.1.4. Receive Label Release ...........................109
A.1.5. Receive Label Withdraw ..........................111
A.1.6. Recognize New FEC ...............................113
A.1.7. Detect Change in FEC Next Hop ...................115
A.1.8. Receive Notification / Label Request Aborted ....118
A.1.9. Receive Notification / No Label Resources .......119
A.1.10. Receive Notification / No Route ................119
A.1.11. Receive Notification / Loop Detected ...........120
A.1.12. Receive Notification / Label Resources Available 121
A.1.13. Detect Local Label Resources Have Become
Available ......................................122
A.1.14. LSR Decides to No Longer Label Switch a FEC ....123
A.1.15. Timeout of Deferred Label Request ..............123
A.2. Common Label Distribution Procedures ....................124
A.2.1. Send_Label ......................................124
A.2.2. Send_Label_Request ..............................125
A.2.3. Send_Label_Withdraw .............................127
A.2.4. Send_Notification ...............................127
A.2.5. Send_Message ....................................128
A.2.6. Check_Received_Attributes .......................128
A.2.7. Prepare_Label_Request_Attributes ................129
A.2.8. Prepare_Label_Mapping_Attributes ................131