Himanshu Shah Ciena Networks PWE3 Working Group Internet Draft Hamid Ould-Brahim Nortel Networks June 2003 Expires: December 2003 Dynamic Parameters Signaling for MPLS-based Pseudowires draft-shah-pwe3-control-protocol-extension-01.txt Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Abstract This document describes a mechanism along with extensions to [PWE3- CONTROL] draft that enable a PE to signal to the remote PE additional dynamic information about the pseudowire. This information may either be related to the operations of the pseudowire such as operational state of the Attachment circuit, the state of the pseudowire forwarders, the IP address and/or MAC address of the attached CE, or may affect the setup of the pseudowire, such as traffic engineering parameters, security related information, etc. Shah, et al. Expires December 2003 1 Internet Draft draft-shah-pwe3-control-protocol-extension-01.txt The proposal is backward compatible with existing [PWE3-CONTROL] based pseudowire and provides a flexible mechanism for learning remote end additional capabilities without requiring complex, explicit pseudowire negotiation extensions and procedures. 1.0 Specification of Requirements 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. 2.0 Introduction The [PWE3-CONTROL] draft describes how two PEs signal VC-FEC to each other in order to establish a pseudowire. The VC-FEC is exchanged over the targeted LDP session and contains pseudowire signaling information that is generally pre-provisioned and static (i.e., does not change during the lifetime of the pseudowire). However, there are situations and events that occur during the lifetime of the pseudowire where a PE needs to inform the remote PE about the up-to-date information related to normal functioning of the pseudowire. Such information allows the receiving PE to take appropriate actions when required. The additional information may either be related to the operations of the pseudowire such as state of the Attachment circuit, the state of the pseudowire forwarders, the IP address and/or MAC address of the attached CE, etc, or may affect setup of the pseudowire, such as traffic engineering parameters, security related information, type of tunnel signaling used, VPN related information, etc. These drafts describes a mechanism whereby additional information about the pseudowire can be dispatched with the VC-FEC without requiring to a) tear down the pseudowire by withdrawing the PW-Label and b) explicitly negotiate capabilities between PW PE peers. This document does not define all the information elements that can be passed optionally with the VC-FEC but rather a mechanism whereby such information can be passed either during the setup or as an update without requiring to tear down the existing pseudowire. This document specifies various TLVs that can be included in the initial Label Mapping Message and subsequently in LDP notification message for conveying up-to-date information about the pseudowire. Finally, this proposal is orthogonal to the type of VC-FEC used. Both PWid FEC and Generalized ID FEC can make use of the new additions. In the case of PWid FEC and for particular TLVs (such as Status TLV) the additional signaled information can be related to the GROUP_ID value when this field is used in signaling. Shah, et al. Expires December 2003 2 Internet Draft draft-shah-pwe3-control-protocol-extension-01.txt 3.0 Capability Learning and Dynamic Update Mechanisms For the purpose of learning remote end capabilities and for the purpose of signaling to the remote end the local capabilities, this draft suggests that the various additional TLVs to be included initially in the label mapping message and particularly in the Optional Parameter field of Label Mapping Message. When subsequent updates are required (after the PW is established), the sender PE will use the LDP notification message to convey an update of the new information.. Note that the mechanism described in this draft allows a given PE that does not support the additional TLVs to be able to establish a pseudowire using normal operations. Indeed, the PEs that are upgraded with such new functionality, examine the optional parameters and note each TLV to learn the capabilities of the sending peer. The sender must include all the TLVs that it intends to use later as an update in the Label Mapping message that is used to setup the FIB. Typically, such Label Mapping message is either the first Label Mapping message or the one right after the Label Withdraw/Release message and is referred to in this document as a "Learning Label Mapping" message. The absence of a given TLV in the Learning Label Mapping message indicates to the receiver that the sending PE is either not capable of processing such TLV or does not wish to engage in dynamic update exchange for that TLV. The absence of any additional TLV indicates to the receiving PE that normal PW signaling procedures should be used to establish the PW (i.e., no inclusion of the optional TLVs in the reverse label mapping). Similarly, the receiving PE that has not been upgraded with the new TLVs and receives a label mapping with the new TLVs will just ignore these TLVs during label mapping processing phase. When the receiving PE learns the senderĘs new capabilities it adjusts its behavior as follows: If the receiving PE didn't send its label mapping message, it will then format a label mapping message that contains all the new TLVs matching the received TLVs or contains a subset of TLVs from the matching set that the receiving PE intends to use during the life time of the pseudowire. If however, the label mapping has been sent, the receiving PE will only support the set of TLVs that both the sender and the receiver support (i.e., the common denominator). Once the capabilities of the remote peer has become known and the pseudowire is operational, subsequent updates will be conveyed using the LDP notification message which will contain only a subset or all the TLVs taken from the set of TLVs that both the sender and the receiving PE understand and agreed to exchange. Shah, et al. Expires December 2003 3 Internet Draft draft-shah-pwe3-control-protocol-extension-01.txt Note that for Status TLV (see below), a PE that is capable of supporting this TLV MUST include it in the LABEL MAPPING message. This allows the remote PE to determine the actual Status of various components of a given pseudowire type at the sender PE side. As an example a PE receiving label mapping with negative status information may decide upon local policy to not forward traffic to the sender PE until new status information is received that clears the previous problem. The format of the Notification message 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| Notification (0x0001) | Message Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PW FEC TLV | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | User defined TLV(s) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 4.0 TLVs 4.1 Operational Status TLV The Operational Status TLV is used to notify the remote PE peer about the initial and the change in operational status of the attached circuit or the tunnel carrying the PW. The exchange of this information is an alternative to the current practice of withdrawing the PW label for such circumstances. 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| Status TLV (TBD) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Status | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Status 32-bit value specifies the operational status. A value of 0 means that operational status is active. A value of 1 means that AC or PW is inactive Each PE is responsible for coordinating the status notification for his local AC and PW. For example, if PEx detects AC down and Shah, et al. Expires December 2003 4 Internet Draft draft-shah-pwe3-control-protocol-extension-01.txt notifies PEy and if PEy uses this information to inactivate his corresponding AC, it must not notify back to PEx about his AC down. In effect, each PE must view notifying the status to remote as his responsibility only when his capability to propagate traffic from AC to PW is compromised. The state of the traffic propagation from PW to AC is largely dependent on remote PEĘs status notifications. This rule must be observed to avoid any deadlock arising from interdependent status exchanges. 4.2 IP Address TLV The IP Address TLV is used to notify the remote PE about the IP address of the locally attached CE. This information is useful for point-to-point Layer 2 interworking circuit [SHAH-ARP]. 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| IP Address TLV (TBD) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IP Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ IP Address 32-bit field contains IP address of the attached CE. When value is zero, the IP address of the attached CE is not known or has become unknown. The [SHAH-ARP] draft describes the need to exchange and how to process such information. 4.3 IP+MAC Address TLV The IP+MAC Address TLV is used to notify the remote PE about the IP and MAC address of the locally attached CE. This information is useful for multipoint-to-multipoint pseudowire for IP as described in [SHAH-IPLS] document. 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| IP Address TLV (TBD) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IP Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MAC Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MAC Address | Multicast Flag | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ IP Address Shah, et al. Expires December 2003 5 Internet Draft draft-shah-pwe3-control-protocol-extension-01.txt 32-bit field contains IP address of the attached CE. When value is zero, the IP address of the attached CE is not known or has become unknown. MAC Address 48-bit field contains MAC address of the attached CE. When the value is zero, the MAC address of the attached CE is not known or has become unknown. Multicast Flag Value one indicates that pseudowire carry only multicast traffic. The [SHAH-IPLS] draft describes the need to exchange and how to process such information. 4.4 Pseudowire QOS TLV The pseudowire QOS TLV is used to notify the remote PE about tunnel signaling mechanisms and traffic engineering parameters to be used to setup the ingress pseudowire from the remote to the advertising PE. As stated earlier, this information can also be passed as an update. It is possible that receiver may either adjust QOS parameters of the existing tunnel or may respond to the update by first withdrawing the advertised PW label and re-advertise new PW label with same VC-FEC. 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| PW QOS TLV (TBD) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Tunnel Type | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Committed Information Rate (CIR) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Peak Information Rate (PIR) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Committed Burst Size (CBS) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Peak Burst Size (PBS) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Tunnel Type 16-bit value identifies the signaling mechanisms to be used to setup the tunnel over which the PW is mapped. A value of 0 indicates that tunnel type is not specified. A value of 1 indicates use of LDP and a value of 2 indicate use of RSVP-TE. When tunnel type is LDP, QOS parameters are ignored. When there is a mismatch between the sender and the receiverĘs Tunnel Type, receiver and sender both defaults to LDP tunnel type. Traffic Engineering Parameters Shah, et al. Expires December 2003 6 Internet Draft draft-shah-pwe3-control-protocol-extension-01.txt Each TE parameter is encoded as a 32-bit IEEE single precision floating-point number. The CIR and PIR are in units of bytes per second while CBS and PBS are in units of bytes. The PW QOS TLV conveys traffic engineering parameters that advertising PE would like remote PE to consider when selecting/creating appropriate transport tunnel to carry the pseudowire from remote PE to the advertising PE. The traffic engineering parameters can also be used to select appropriate traffic shaper and policer for the attached circuit at the remote PE. 5.0 General Procedures The TLVs described in this document are mandatory for some pseudowire types and layer-2 vpn services (e.g. ARP mediation, IPLS).. In general, when Notification message is used as an update mechanism and ęwithdrawĘ of optional parameters is realized by issuing the Notification message with same TLVs as an update with null values in some cases. This alleviates the need to cycle through Label Withdraw followed by Label Mapping message to convey new parameters as is the current situation with [PWE3-CONTROL]. Future revision of this document will contain additional information of other TLVs that are useful as adjunct information for the VC-FEC. 6.0 Security Considerations The security aspects of this solution will be discussed at a later time. 7.0 References [PWE3-CONTROL] Martini et. Al., "Transport of Layer 2 Frames Over MPLS", draft-ietf-pwe3-control-protocol-02.txt, February 2003 (work in progress) [LDP] L. Andersson, P. Doolan, N. Feldman, A. Fredette, B. Thomas, "LDP Specification", RFC3036, January 2001. [SHAH-ARP] Shah et. Al., "ARP Mediation for IP interworking of Layer 2 VPN", Draft-shah-ppvpn-arp-mediation-02.txt, June 2003 (work in progress) [SHAH-IPLS] Shah et. Al., "IP-Only LAN Service", Draft-shah-ppvpn- ipls-02.txt. June 2003. (work in progress). Acknowledgement The authors would like to thank David Allan for his constructive input. Shah, et al. Expires December 2003 7 Internet Draft draft-shah-pwe3-control-protocol-extension-01.txt Author's Address Himanshu Shah Ciena Networks 35 Nagog Park Acton, MA 01720 Email: hshah@ciena.com Hamid Ould-Brahim Nortel Networks P O Box 3511 Station C Ottawa, ON K1Y 4H7, Canada Email: hbrahim@nortelnetworks.com Full copyright statement Copyright (C) The Internet Society (1999). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Shah, et al. Expires December 2003 8