| Found Source Forwarder? ----------> End
| |
| Y |
| v
| Pick Next <--------------------------------
| Target Forwarder |
| | |
| | |
| N v |
-------- Found Target Forwarder? |
| |
Y | |
v Y Y |
Same Router ID? ------> Same Forwarder ID? ------|
| | |
N | N | |
| v |
| Create Local -------|
v Cross-connect |
Pseudowire Already Y |
Established Between -------------------------------|
Source and Target? |
| |
N | |
v |
Local Initiates Pseudowire |
Connection Request to Remote |
| |
| |
v |
-------> Local Wait for Message |
| ----- from Remote -------------- |
| | | |
| | | |
| v v |
| Local Receives Pseudowire Local Receives Pseudowire |
| Connection Request Connection Response |
| from Remote from Remote |
| | | |
| | | |
| v v N |
| Perform Pseudowire Connection Accepted? --------|
| Tie Detection | |
| | Y | |
| | v |
| | Local Binds Source ---------|
| | Forwarder to Pseudowire |
| | |
| v N N |
| Tie Detected? -----> Accept Remote -----> Reject ------|
| | Connection Request? Remote Request |
| Y | ^ | |
| v | | Y |
| Perform Tie Breaking | ------> Local Binds ----
| | | Source Forwarder
| | | to Pseudowire
| v N |
| Won Tie Breaking? ------> Disconnect
| | Local Connection
| Y |
| v
------ Ignore Remote
Connection Request
6. IANA Considerations
The IANA registry procedure in this document follows that in Section
10 of [RFC3931]. The IANA has assigned the following new values for
existing registries managed by IANA.
This document defines three new L2TP control message Attribute Value
Pairs (AVPs) that have been assigned by the IANA. These are
described in Section 4.3 and are summarized below:
89 - Attachment Group Identifier
90 - Local End Identifier
91 - Interface Maximum Transmission Unit
Sections 4.3 and 5.1 define three new result codes for the CDN
message that have been assigned by the IANA:
23 - Mismatching interface MTU
24 - Attempt to connect to non-existent forwarder
25 - Attempt to connect to unauthorized forwarder
7. Security Considerations
This specification does not introduce any additional security
considerations beyond those discussed in [RFC3931] and [L2VPNFW].
8. Acknowledgement
The author would like to thank Mark Townsley and Carlos Pignataro for
their valuable input.
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3931] Lau, J., Townsley, M., and I. Goyret, "Layer Two Tunneling
Protocol - Version 3 (L2TPv3)", RFC 3931, March 2005.
9.2. Informative References
[PWE3IANA] Martini, L., "IANA Allocations for Pseudowire Edge to Edge
Emulation (PWE3)", BCP 116, RFC 4446, April 2006.
[L2VPNFW] Andersson L., Ed. and E. Rosen, Ed., "Framework for Layer
2 Virtual Private Networks (L2VPNs)", RFC 4664, September
2006.
[PWE3L2TP] W. Townsley, "Pseudowires and L2TPv3", Work in Progress.
[RFC2661] Townsley, W., Valencia, A., Rubens, A., Pall, G., Zorn,
G., and B. Palter, "Layer Two Tunneling Protocol "L2TP"",
RFC 2661, August 1999.
Author’s Address
Wei Luo
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA 95134
EMail: luo@cisco.com
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