Internet DRAFT - draft-zi-pwe3-link-aggr-member-status
draft-zi-pwe3-link-aggr-member-status
Pseudo-Wire Emulation Edge-to-Edge(PWE3) Zi Kang
Liu Jun
Internet Draft Huawei Technologies Co., Ltd.
Expires: April 2006 October 17, 2005
Link Aggregation Member Interface Status Signal
draft-zi-pwe3-link-aggr-member-status-00.txt
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Copyright (C) The Internet Society (2005). All Rights Reserved.
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Abstract
Link Aggregation can be used as Attachment Circuit (AC) of the PWE3
service. Link Aggregation is treated as a single interface. But
changes in the the member interface may affect use of the aggregated
link.
This draft suggests a method to signal the status of the member
interface of Link Aggregation AC to remote Provider Edge (PE) device.
With this status information, the remote PE can decide to discard
traffic over bandwidth, avoid congestion at local PE and avoid wasted
bandwidth of the Packet Switched Network (PSN).
This mechanism is required in PWE3 applications because pseudo-wires
provide layer 1/layer 2 services, carrying traffic that may not
respond to loss events by executing congestion avoidance
Conventions used in this document
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 RFC-2119 [1].
Table of Contents
1. Introduction................................................2
2. AC Sub-interface Status......................................3
3. Security Considerations......................................5
4. IANA Considerations.........................................5
5. Acknowledgments.............................................6
6. Normative References.........................................6
7. Informative References.......................................6
8. Author's Addresses..........................................7
Intellectual Property Statement.................................7
Disclaimer of Validity.........................................8
Copyright Statement............................................8
Acknowledgment.................................................8
1. Introduction
A Link Aggregation interface can be used as an Attachment Circuit (AC)
of PWE3 service. A Link Aggregation interface is treated as a single
interface.
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If, for example, a Link Aggregation includes two operational 100 Mb
Ethernet ports, the Link Aggregation interface can pass through 200
Mb traffic.
If one of the two ports changes it's status to 'down', the Link
Aggregation interface can pass through only 100 Mb traffic.
Because the Link Aggregation interface is still up, so the remote
Customer Edge (CE) device continues to send out 200 Mb traffic. The
200 Mb traffic may be forwarded to this PE which must discard one
half of the traffic.
So we need a mechanism to communicate the status of the member
interface of the Link Aggregation interface to the remote PE.
2. AC Sub-interface Status
The member interface of the Link Aggregation interface can be
regarded as a sub-interface of AC.
The format of the AC Sub-interface Status TLV is 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1 0| AC Sub-interface Status | 0x0C |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Number of up Sub-interface | Bandwidth Unit |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bandwidth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The values of Bandwidth Unit are specified below:
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0x01 bps
0x02 Kbps
0x03 Mbps
0x04 Gbps
So the bandwidth of Link Aggregation interface is equal to
"Bandwidth" multiplied by "Bandwidth Unit".
This TLV is transported to the remote PW peer via the LDP
notification message ([PWE3-CRTL] 5.4.2), with the PW Status TLV. The
general format of the Notification Message is:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| Notification (0x0001) | Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Status (TLV) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PW Status TLV |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AC Sub-interface Status TLV |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PWId FEC or Generalized ID FEC |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
When one of the member interfaces of the Link Aggregation changes to
down or up, a PE that supports this mechanism MUST send the AC Sub-
interface Status TLV via a notification message to the remote PE.
If the remote PE does not know how to process this TLV, it MUST
ignore this TLV because the U bit of this TLV is set [RFC3031].
A remote PE that does know how to process this TLV MAY perform flow
control mechanism using the new bandwidth. The number of up Sub-
interface may also be used for flow control mechanism.
If one of the member interfaces of the Link Aggregation changes to
down, but at the same time another member interfaces of the Link
Aggregation changes to up, and the bandwidth of Link Aggregation not
change, the PE MAY send the AC Sub-interface Status TLV to the remote
PE, but is not required to do so if the aggregate bandwidth and
number of active member interfaces remain constant.
3. Security Considerations
This document does not introduce any new security concerns beyond
those specified in [PWE3-CRTL].
4. IANA Considerations
The code of AC Sub-interface Status TLV must be assigned by IANA.
(Spencer - is there a value you could suggest? May not need.)
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5. Acknowledgments
None.
6. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] Crocker, D. and Overell, P.(Editors), "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, Internet Mail Consortium and
Demon Internet Ltd., November 1997.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2234] Crocker, D. and Overell, P.(Editors), "Augmented BNF for
Syntax Specifications: ABNF", RFC 2234, Internet Mail
Consortium and Demon Internet Ltd., November 1997.
[PWE3-CRTL] "Pseudowire Setup and Maintenance using the Label
Distribution Protocol", Martini L., et al draft-ietf-pwe3-
control-protocol-17.txt, ( work in progress ), June 2005.
[RFC3031] E. Rosen, et al., RFC 3031, MPLS Architecture, January 2001.
7. Informative References
[RFC3985] "PWE3 Architecture" Bryant, et al., RFC3985.
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8. Author's Addresses
Zi Kang
Huawei Technologies Co., Ltd.
Floor 10, HuiHong Mansion, No.91 BaiXia Rd.
NanJing, P.R. of China
Phone: ( 86)25-84565325
Email: zikang@huawei.com
Liu Jun
Huawei Technologies Co., Ltd.
Floor 10, HuiHong Mansion, No.91 BaiXia Rd.
NanJing, P.R. of China
Phone: ( 86)25-84565327
Email: liujn@huawei.com
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Acknowledgment
Funding for the RFC Editor function is currently provided by the
Internet Society.
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