Internet DRAFT - draft-hu-pce-auxiliary-connections
draft-hu-pce-auxiliary-connections
PCE WG Fangwei. Hu
Internet-Draft Ran. Chen
Intended status: Standards Track ZTE Corporation
Expires: June 15, 2017 December 12, 2016
PCE auxiliary connections
draft-hu-pce-auxiliary-connections-00.txt
Abstract
This document provides a method to establish auxiliary connections
between PCE and PCC to improve the reliability of the connection of
PCE and PCC. The real-time sample data and some state report flow
are suggestion to transport by take use of the auxiliary connection.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used in This Document . . . . . . . . . . . . . . 3
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
3. New Functions to Support auxiliary connections . . . . . . . 3
4. Overview of Protocol Extensions . . . . . . . . . . . . . . . 3
4.1. Auxiliary-Connections-Capability-TLV . . . . . . . . . . 3
4.2. Capability Advertisement . . . . . . . . . . . . . . . . 5
4.3. Initialization Phase . . . . . . . . . . . . . . . . . . 5
4.4. Termination of the Auxiliary Connections PCEP Session . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
8. Informative References . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
The Path Computation Element Protocol (PCEP) defined in [RFC5440] is
used between a Path Computation Element (PCE) and a Path Computation
Client (PCC) (or other PCE) to enable computation of Multi-protocol
Label Switching (MPLS) for Traffic Engineering Label Switched Path
(TE LSP).
PCEP is a recommendation south-bound interface protocol, and PCE acts
as a controller, and PCCs are the SDN switch being managed by PCE.
The PCC should report the link state and flow statistics in the SDN
environment. The data going through the PCEP channel may be very
huge. The PCEP session and the TCP connection may be occupied by the
flow sample and be congested for the PCEP packet. So it is important
to improve the reliability of the PCE and the connection between PCE
and PCC.
This document provides to establish auxiliary connections between PCE
and PCC to improve the reliability of the connection of PCE and PCC.
The real-time sample data and some state report flow are suggestion
to transport by take use of the auxiliary connection. And the
original connection (we name it main connection) are used to
transport the PCEP protocol message (such as PCE PCReq message, PCRep
message, PCRpt message, PCUpd mesage, PCInitiate message
,etc.)([RFC5440], [I-D.ietf-pce-stateful-pce],
[I-D.ietf-pce-pce-initiated-lsp]).
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2. Conventions Used in This Document
2.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
2.2. Terminology
This document uses the following terms defined in ([RFC5440]:PCC,
PCE, PCEP Peer.
The following terms are defined in this document:
Main connection: The PCEP session between PCE and PCC peer. It is
defined in [RFC5440]. It is renamed as main connection in this
document.
Auxiliary connection: the addition connection session beyond the main
connection. It is used to improve the reliability of main
connection.
3. New Functions to Support auxiliary connections
A new function is required in PCEP to support auxiliary connections.
A function can be initiated either from a PCC towards a PCE (C-E) or
from a PCE towards a PCC (E-C). The new function is:
Capability advertisement (E-C, C-E): both the PCC and the PCE must
announce during PCEP session establishment that they support
auxiliary connection defined in this document.
4. Overview of Protocol Extensions
4.1. Auxiliary-Connections-Capability-TLV
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type[TBD] | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Auxiliary Connections number | Res |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ \
| Auxiliary Connection1 ID | Length | |
+--------------------------------+------------------------------+ > Auxiliary
| transport protocol | port number | | Connetction 1
+--------------------------------+------------------------------+ |
| option | /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ \
| Auxiliary Connection2 ID | Length | |
+--------------------------------+------------------------------+ |
| transport protocol | port number | > Auxiliary
+--------------------------------+------------------------------+ | Connetction 2
| option | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ /
Figure 1 Auxiliary-Connections-Capability-TLV
o Type:
o Length: the whole length of TLV
o Auxiliary Connections number: the record number of auxiliary
connections.
o Res: reserve for future use.
o Auxiliary Connection ID: the identifier of the auxiliary
connection.
o Length:the length for the auxiliary connection.
o transport protocol: the transport protocol for the auxiliary
connection. The value is as following:
o TCP 1;
o UDP 2;
o TLS 3;
o DTLS 4;
o port number: port number used for the transport protocol in the
auxiliary connection.
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o Option: Optional data. The extra optional data is filled in the
filled. For example, if the transport protocol is TLS, the secret
key is filled in the field.
4.2. Capability Advertisement
During PCEP Initialization Phase, PCEP Speakers (PCE or PCC)
advertise their support auxiliary connections. A PCEP Speaker
includes the " Auxiliary-Connections-Capability" TLV, described in
Section 5.1, in the OPEN Object to advertise its support for
auxiliary connections. The Auxiliary Connections Capability TLV
includes the auxiliary connection parameters.
The presence of the auxiliary connection Capability TLV in PCC's OPEN
Object indicates that the PCC is willing to establish auxiliary
connection with PCE.
The presence of the auxiliary connection Capability TLV in PCE's OPEN
message indicates that the PCE is willing to establish auxiliary
connection with PCC.
4.3. Initialization Phase
The PCE peer must not initiate auxiliary connection before having
completed the connection setup overthe main connection; it must setup
and maintain auxiliary connections with the PCE peer only while the
corresponding main connection is alive. The connection setup for
auxiliary connections is the same as for the main connection. The
procedure of auxiliary connection is as following:
PCC sends OPEN message to initiate the main connection. The
auxiliary connections capability is filled in the OPEN object and
carried in the OPEN message.
PCE sends OPEN message to PCC carring the auxiliary connections
capability in the OPEN message too.
After receiving the OPEN message from PCE, PCC establishes PCEP
session, and sends the keepalive message to enable the keepalive
mechanism. The keepalive message is transported relying on the main
connection. If one end of the main connection session receives no
message before the DeadTimer expires, it declares the session dead.
Once the main connection session and the transport connection for the
auxiliary connection are established, the PCC and PCE initiatet the
auxiliary connections PCEP session establishment.
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After receiving the OPEN message from the PCEP peer, the other PCEP
peer establishes PCEP session, and sends the keepalive message to
enable the keepalive mechanism. The keepalive message is transported
relying on the auxiliary connection. If one end of the auxiliary
connection session receives no message before the DeadTimer expires,
it declares the session dead and close the auxiliary connection. If
the PCEP peer notices that the main connection session is dead, the
auxiliary connection will be closed.
+-+-+ +-+-+
|PCC| |PCE|
+-+-+ +-+-+
| |
| Open msg(C->E, |
| Main Connection) |
|------------------------>|
| |
| |
| Open msg(E->C, |
| Main Connection) |
|<------------------------|
| |
| Keepalive |
| (Main Connection) |
|------------------------>|
| |
| Keepalive |
| (Main Connection) |
|<------------------------|
| |
| Open msg(C->E, |
| auxiliary Connection) |
|------------------------>|
| |
| Open msg(E->C, |
| Main Connection) |
|<------------------------|
| Keepalive |
| (auxiliary Connection) |
|------------------------>|
| |
| Keepalive |
| (auxiliary Connection) |
|<------------------------|
Figure 2 Initialization Phase
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4.4. Termination of the Auxiliary Connections PCEP Session
The termination of the auxiliary connections PCEP session could be
triggered by the close of main connection or the auxiliary
connection's PCEP peer itself.
If PCC desires to close the main connection, PCC sends the close
message to PCE. When PCE receives the close message, it closes all
the auxiliary connections with the PCC firstly, then clears all the
states related to pending requests previously sent to the PCC and
closes the main connection. The procedure is described in figure 2.
Similarly, if the PCE desires to close the main connection, The PCC
close all the auxiliary connections with the PCE firstly, then clears
all the states related to pending requests previously sent to the PCE
and closes the main connection.
+-+-+ +-+-+
|PCC| |PCE|
+-+-+ +-+-+
| |
| Close msg(C->E, |
| Main Connection) |
|------------------------>|
| |
| | 1)Close message received
| |
| | 2)Close auxliary connection
| |
| | 3)Close main connection
Figure 3 Close Main Connection
When one of the PCEP peers desires to terminate an auxiliary
connection PCEP session, it first sends a PCEP Close message based on
the auxiliary connection and then closes the TCP connection.
If the PCEP session is terminated by the PCE, the PCC clears all the
states related to auxiliary connection pending requests previously
sent to the PCE.
Similarly, if the PCC terminates a PCEP session, the PCE clears all
auxiliary connection pending path computation requests sent by the
PCC in question as well as the related states. Figure 3 shows the
procedure.
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+-+-+ +-+-+
|PCC| |PCE|
+-+-+ +-+-+
| |
| Close msg(C->E, |
| auxiliary Connection) |
|------------------------>|
| |
| |
| | 1)Close message received
| |
| | 2)Close auxliary connection
| |
| |
Figure 4 Close Auxliary Connection
5. Security Considerations
TBD
6. IANA Considerations
There is no need additional IANA allocation for this document.
7. Acknowledgements
TBD.
8. Informative References
[I-D.ietf-pce-pce-initiated-lsp]
Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "PCEP
Extensions for PCE-initiated LSP Setup in a Stateful PCE
Model", draft-ietf-pce-pce-initiated-lsp-07 (work in
progress), July 2016.
[I-D.ietf-pce-stateful-pce]
Crabbe, E., Minei, I., Medved, J., and R. Varga, "PCEP
Extensions for Stateful PCE", draft-ietf-pce-stateful-
pce-18 (work in progress), December 2016.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
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[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<http://www.rfc-editor.org/info/rfc5440>.
Authors' Addresses
Fangwei Hu
ZTE Corporation
No.889 Bibo Rd
Shanghai 201203
China
Phone: +86 21 68896273
Email: hu.fangwei@zte.com.cn
Ran Chen
ZTE Corporation
No.50 Software Avenue,Yuhuatai District
Nanjing, Jiangsu Province 210012
China
Phone: +86 025 88014636
Email: chen.ran@zte.com.cn
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