Network Working Group L. Jin
Internet-Draft R. Chen
Intended status: Standards Track ZTE
Expires: April 12, 2013 S. Boutros
Cisco Systems
S. Kini
Ericsson
October 9, 2012
Static pseudowire configuration checking using Generic Associated
Channel (G-ACh) Advertisement Protocol
draft-jc-pwe3-static-config-check-01.txt
Abstract
This document defines a method to verify the configuration parameters
of static pseudowires (PW). Since a static PW can be independently
provisioned at each end of the PW there is a potential for a
configuration parameter mismatch and this can result in the PW not
being operational. This document introduces a configuration checking
protocol to simplify the provisioning and ease trouble shooting.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 12, 2013.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
Jin, et al. Expires April 12, 2013 [Page 1]
Internet-Draft draft-jc-pwe3-static-config-check-00 October 2012
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. GAP Extensions . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Static PW Application Message . . . . . . . . . . . . . . 4
3.2. PE Procedure for SS-PW . . . . . . . . . . . . . . . . . . 7
3.2.1. Sending PW application Element TLV . . . . . . . . . . 7
3.2.2. Receiving PW application Element TLV . . . . . . . . . 7
3.2.3. PW Configuration Verification Process . . . . . . . . 8
3.2.4. Remote Label Advertisement . . . . . . . . . . . . . . 8
3.3. PE Procedure for MS-PW . . . . . . . . . . . . . . . . . . 8
4. Security Considerations . . . . . . . . . . . . . . . . . . . 9
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9
7.1. Normative references . . . . . . . . . . . . . . . . . . . 9
7.2. Informative References . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10
Jin, et al. Expires April 12, 2013 [Page 2]
Internet-Draft draft-jc-pwe3-static-config-check-00 October 2012
1. Introduction
The manual configuration of static PW in MPLS and MPLS-TP network
requires configuring different PW parameters at the two terminating
PEs (Provider Edge). The PW parameters include PW-id, PW-Type,
Control word setting, interface and VCCV parameters settings.
The PW provisioned parameters MUST be aligned, so as to make the PW
operational. For dynamically signaled PW, the PW parameters are
negotiated using the signaling protocol, and only when the PW
parameters match at the terminating PE end points, the P2P (Point-to-
Point) PW is made operational and can be used to forward data
traffic.
In the absence of a signaling protocol, this draft defines a method
to do static PW configuration verification, so as to ease the
troubleshooting of end to end static PW provisioning in both MPLS and
MPLS-TP networks. The mechanism to exchange the PW configuration
parameters uses the Generic Associated Channel (G-ACh) Advertisement
Protocol (GAP) defined in [I-D.ietf-mpls-gach-adv]. In this draft,
the GAP functionality assumes that the PW's underlying PSN Tunnel
with GAP enabled is operational.
In the following sections we will describe the extension to the GAP
mechanism to do the PW configuration verification at the two
terminating PEs for P2P PW. The P2MP (Point-to-Multipoint) PW
configuration verification is for further study.
2. Terminology
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].
This document uses some terms and acronyms as follows:
MPLS: Multi Protocol Label Switching.
OAM: MPLS Operations, Administration and Maintenance.
PE: Provide Edge Node.
T-PE: PW Terminating Provider Edge.
S-PE: PW Switching Provider Edge.
Jin, et al. Expires April 12, 2013 [Page 3]
Internet-Draft draft-jc-pwe3-static-config-check-00 October 2012
PW: PseudoWire.
TLV: Type, Length, and Value.
SS-PW: Single-segment PseudoWire
MS-PW: Multi-segment PseudoWire
3. GAP Extensions
3.1. Static PW Application Message
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Static PW | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Lifetime | Reserve |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Static PW FEC Element TLV +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1
A new GAP application "Static PW" is defined in this draft. The
Static PW Application ID is to be assigned by IANA, and suggested
value is 0x0002.
Length: as per [I-D.ietf-mpls-gach-adv].
Lifetime: as per [I-D.ietf-mpls-gach-adv], and the default value is
suggested to be 120 seconds.
Static PW FEC Element TLV for "Static PW" GAP application:
Jin, et al. Expires April 12, 2013 [Page 4]
Internet-Draft draft-jc-pwe3-static-config-check-00 October 2012
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 | Reserved | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Global ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Node ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source AC-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Global ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Node ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination AC-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PW Type |C| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TX Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RX Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0| Label Sub-TLV(0x0200) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Incoming Label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0| Label Sub-TLV(0x0200) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Outgoing Label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Optional Interface Parameters Sub-TLV +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2
The Static PW FEC Element TLV type is to be assigned by IANA. The
Length field specifies the length in octets of the Static PW FEC
Element and all Optional Interface Parameters Sub-TLVs.
The Static PW FEC element TLV value MUST include the following:
o The Global ID and Node ID fields MUST be set as per [RFC6370].
Jin, et al. Expires April 12, 2013 [Page 5]
Internet-Draft draft-jc-pwe3-static-config-check-00 October 2012
o The AC-ID fields MUST be set as per [RFC5003].
o PW-Type and control word bit (C) MUST be set as per [RFC4447].
o TX Sequence Number: The transmitted message sequence number for
the associated Static PW FEC Element TLV.
o RX Sequence Number: The last received sequence number for the
associated Static PW FEC Element TLV.
o Two Generic Label TLVs as defined in [RFC5036] to encode static PW
incoming and outgoing labels in the order shown above.
o Optional Interface parameters Sub-TLV as defined in [RFC4447].
The GAP Suppress message defined in [I-D.ietf-mpls-gach-adv] only
applies all TLVs for a given application. We define a new TLV,
static PW suppress TLV, to suppress static PW FEC element
transmission. Multiple static PW FEC element TLVs could be included
in this TLV. The format would be as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|PW Suppress TLV| Reserved | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Static PW FEC Element +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Multiple Static PW FEC Element TLVs ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3
The type of static PW suppress TLV is to be assigned by IANA.
The static PW suppress TLV could be sent by a receiving PE to request
a transmitting PE to stop sending GAP messages for the static PW FEC
Element TLVs in the static PW suppress TLV.
The static PW application MUST follow all procedures defined in
[I-D.ietf-mpls-gach-adv].
Jin, et al. Expires April 12, 2013 [Page 6]
Internet-Draft draft-jc-pwe3-static-config-check-00 October 2012
3.2. PE Procedure for SS-PW
The mechanism defined in this draft provides a verification tool for
the P2P PW configuration information between two PEs. Upon the
provisioning or re-provisioning of a PW at an endpoint PE, GAP
messages carrying the static PW application TLV will be sent over the
PW's corresponding PSN tunnel which the endpoints PEs of the P2P PW
selects by local policy.
3.2.1. Sending PW application Element TLV
When a PW is configured at one endpoint PE, and the PW corresponding
PSN Tunnel is operational and UP, the PE MUST send its local PW
configuration information using the GAP over the PSN tunnel.
The transmitting PE MUST set the TX sequence number to a non-zero
value in Static PW FEC Element TLV, and MUST increment the TX
sequence number each time any local PW parameters change.
If the transmitting PE has previously received a GAP message with the
static PW FEC Element, the transmitting PE MUST verify local PW
parameters with the remote PE parameters as specified in section
4.2.3. The RX sequence number MUST be set to the previously received
TX sequence number, otherwise set to zero.
3.2.2. Receiving PW application Element TLV
The receiving PE MUST update the remote PW parameters associated with
a static PW FEC Element TLV, when the received TX sequence number in
the GAP message is different from the last one received.
If the receiving PE has been provisioned locally with the PW
parameters and has previously sent GAP message for the PW parameters,
it MUST check if the RX sequence number in the received GAP message
is equal to the TX sequence number it previously sent.
If the RX sequence number is equal, the receiving PE MUST send GAP
message with static PW suppress TLV as a response to remote PE, and
then verify local static PW parameters with the remote static PW FEC
parameters as specified in section 3.2.3.
Otherwise, if the RX sequence number is not equal, the receiving PE
MUST continue sending GAP message with static PW FEC element TLV,
with the RX sequence number set to the last received TX sequence
number from the remote PE.
If there is no local PW configuration associated with the static PW
FEC Element TLV, the receiving PE MUST retain the remote static PW
Jin, et al. Expires April 12, 2013 [Page 7]
Internet-Draft draft-jc-pwe3-static-config-check-00 October 2012
FEC Element information.
Whenever PE receives the GAP message with static PW suppress TLV, it
MUST stop sending GAP messages with the specified static PW FEC
element TLVs included in the static suppress TLV.
The GAP message of static PW application SHOULD be sent at least
three times within lifetime.
The mechanism described above applies as well for MS-PW.
3.2.3. PW Configuration Verification Process
Using source/destination Global-IDs, and source/destination node-ID
and AC-IDs, to identify a locally provisioned static PW, once found,
perform the following parameter verification checks:
1. Check the control word bit (C), and MUST do logical operation
"AND". Only when both ends have the use of control word enabled,
the result would be with control word presented on this PW.
2. Check PW type mismatch as defined in [RFC4447].
3. Check and negotiate interface parameters as defined in [RFC4447].
4. Check incoming and outgoing static PW labels. The local incoming
label should be equal to remote outgoing label, and the local
outgoing label should be equal to remote incoming label,
otherwise checking failed.
3.2.4. Remote Label Advertisement
The mechanism described in this draft MAY also be used to communicate
local static PW labels to allow for single side provisioning of
labels. As such, only incoming label will be included in the GAP
message and this label will be used by the remote PE as the output
label for the PW.
3.3. PE Procedure for MS-PW
The mechanism described above for verifying the SS-PW configuration
applies for MS-PW. As described in section 3.2, an S-PE MUST verify
the incoming and outgoing static PW labels, however no other PW
configuration parameters checking are needed at S-PE, since only the
labels will be configured at S-PE.
An S-PE MUST pass through static PW application TLVs carried in GAP
messages, from one PW segment's corresponding PSN tunnel to the other
Jin, et al. Expires April 12, 2013 [Page 8]
Internet-Draft draft-jc-pwe3-static-config-check-00 October 2012
PW segment's corresponding PSN tunnel.
4. Security Considerations
The mechanisms defined in this draft do not introduce any new threats
more than what's described in [I-D.ietf-mpls-gach-adv].
5. IANA Considerations
IANA is requested to allocate a new "Static PW" Application ID in the
"G-Ach Advertisement Protocol Applications" registry.
Application ID Description Reference
-------------- ---------------------------- ------------
(TBD) Static PW Application (this draft)
This document requests that IANA create a new registry, "GAP Static
PW Application: TLV objects", with fields and initial value as
follows:
Type Name Type ID Reference
----------------------- ------- ------------
Static PW FEC Element 0 (this draft)
Static PW suppress TLV 1 (this draft)
The range of the Type ID field is 0 - 255.
The allocation policy for this registry is IETF Review.
6. Acknowledgements
The authors would like to thank Stewart Bryant, Dan Frost for their
review and contributions.
7. References
7.1. Normative references
[I-D.ietf-mpls-gach-adv]
Frost, D., Bryant, S., and M. Bocci, "MPLS Generic
Associated Channel (G-ACh) Advertisement Protocol",
draft-ietf-mpls-gach-adv-02 (work in progress), May 2012.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
Jin, et al. Expires April 12, 2013 [Page 9]
Internet-Draft draft-jc-pwe3-static-config-check-00 October 2012
7.2. Informative References
[RFC4447] Martini, L., Rosen, E., El-Aawar, N., Smith, T., and G.
Heron, "Pseudowire Setup and Maintenance Using the Label
Distribution Protocol (LDP)", RFC 4447, April 2006.
[RFC5003] Metz, C., Martini, L., Balus, F., and J. Sugimoto,
"Attachment Individual Identifier (AII) Types for
Aggregation", RFC 5003, September 2007.
[RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP
Specification", RFC 5036, October 2007.
[RFC6370] Bocci, M., Swallow, G., and E. Gray, "MPLS Transport
Profile (MPLS-TP) Identifiers", RFC 6370, September 2011.
Authors' Addresses
Lizhong Jin
ZTE Corporation
889, Bibo Road
Shanghai, 201203, China
Email: lizhong.jin@zte.com.cn
Ran Chen
ZTE Corporation
No.19 East Huayuan Road
Beijing, 100191, China
Email: chen.ran@zte.com.cn
Sami Boutros
Cisco Systems, Inc.
3750 Cisco Way
San Jose, California 95134
USA
Email: sboutros@cisco.com
Jin, et al. Expires April 12, 2013 [Page 10]
Internet-Draft draft-jc-pwe3-static-config-check-00 October 2012
Sriganesh Kini
Ericsson
Ericsson
San Jose, CA 95134
Email: sriganesh.kini@ericsson.com
Jin, et al. Expires April 12, 2013 [Page 11]