PCE Working Group R. Pobbathi Internet-Draft V. KumarS Intended status: Standards Track D. Dhody, Ed. Expires: April 12, 2015 Huawei Technologies J. Hardwick Metaswitch October 9, 2014 A YANG Data Model for Path Computation Element Communications Protocol (PCEP) draft-pkd-pce-pcep-yang-00 Abstract This document defines a YANG data model for the management of Path Computation Element communications Protocol (PCEP) for communications between a Path Computation Client (PCC) and a Path Computation Element (PCE), or between two PCEs. The data model includes configuration data and state data (status information and counters for the collection of statistics). 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, 2015. Copyright Notice Copyright (c) 2014 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 publication of this document. Please review these documents Pobbathi, et al. Expires April 12, 2015 [Page 1] Internet-Draft PCE-YANG October 2014 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 . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3 3. Terminology and Notation . . . . . . . . . . . . . . . . . . 3 3.1. Tree Diagrams . . . . . . . . . . . . . . . . . . . . . . 4 3.2. Prefixes in Data Node Names . . . . . . . . . . . . . . . 4 4. Objectives . . . . . . . . . . . . . . . . . . . . . . . . . 4 5. The Design of PCEP Data Model . . . . . . . . . . . . . . . . 5 5.1. The Entity Lists . . . . . . . . . . . . . . . . . . . . 8 5.2. The Peer Lists . . . . . . . . . . . . . . . . . . . . . 9 5.3. The Session Lists . . . . . . . . . . . . . . . . . . . . 9 6. Advanced PCE Features . . . . . . . . . . . . . . . . . . . . 10 7. PCEP YANG Module . . . . . . . . . . . . . . . . . . . . . . 10 8. Security Considerations . . . . . . . . . . . . . . . . . . . 40 9. Manageability Considerations . . . . . . . . . . . . . . . . 40 9.1. Control of Function and Policy . . . . . . . . . . . . . 41 9.2. Information and Data Models . . . . . . . . . . . . . . . 41 9.3. Liveness Detection and Monitoring . . . . . . . . . . . . 41 9.4. Verify Correct Operations . . . . . . . . . . . . . . . . 41 9.5. Requirements On Other Protocols . . . . . . . . . . . . . 41 9.6. Impact On Network Operations . . . . . . . . . . . . . . 41 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 41 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 41 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 41 12.1. Normative References . . . . . . . . . . . . . . . . . . 41 12.2. Informative References . . . . . . . . . . . . . . . . . 41 Appendix A. Contributor Addresses . . . . . . . . . . . . . . . 43 1. Introduction The Path Computation Element (PCE) defined in [RFC4655] is an entity that is capable of computing a network path or route based on a network graph, and applying computational constraints. A Path Computation Client (PCC) may make requests to a PCE for paths to be computed. PCEP is the communication protocol between a PCC and PCE and is defined in [RFC5440]. PCEP interactions include path computation requests and path computation replies as well as notifications of specific states related to the use of a PCE in the context of Pobbathi, et al. Expires April 12, 2015 [Page 2] Internet-Draft PCE-YANG October 2014 Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS) Traffic Engineering (TE). This document defines a YANG [RFC6020] data model for the management of PCEP speakers. It is important to establish a common data model for how PCEP speakers are identified, configured, and monitored. The data model includes configuration data and state data (status information and counters for the collection of statistics). This document contains a specification of the base PCEP YANG module, "ietf-pcep" which provides the basic PCEP [RFC5440] data model. [Editor's Note: Further modules augmenting the data model with advanced features maybe handled in a future revision or a separate document.] 2. 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]. 3. Terminology and Notation This document uses the terminology defined in [RFC4655] and [RFC5440]. In particular, it uses the following acronyms. o Path Computation Request message (PCReq). o Path Computation Reply message (PCRep). o Notification message (PCNtf). o Error message (PCErr). o Request Parameters object (RP). o Synchronization Vector object (SVEC). o Explicit Route object (ERO). This document also uses the following term defined in [I-D.ietf-pce-pcep-mib]: o PCEP entity: a local PCEP speaker. o PCEP peer: to refer to a remote PCEP speaker. Pobbathi, et al. Expires April 12, 2015 [Page 3] Internet-Draft PCE-YANG October 2014 o PCEP speaker: where it is not necessary to distinguish between local and remote. 3.1. Tree Diagrams A graphical representation of the complete data tree is presented in Section 5. The meaning of the symbols in these diagrams is as follows and as per [I-D.ietf-netmod-rfc6087bis]: o Brackets "[" and "]" enclose list keys. o Curly braces "{" and "}" contain names of optional features that make the corresponding node conditional. o Abbreviations before data node names: "rw" means configuration (read-write), and "ro" state data (read-only). o Symbols after data node names: "?" means an optional node and "*" denotes a "list" or "leaf-list". o Parentheses enclose choice and case nodes, and case nodes are also marked with a colon (":"). o Ellipsis ("...") stands for contents of subtrees that are not shown. 3.2. Prefixes in Data Node Names In this document, names of data nodes and other data model objects are often used without a prefix, as long as it is clear from the context in which YANG module each name is defined. Otherwise, names are prefixed using the standard prefix associated with the corresponding YANG module, as shown in Table 1. +--------+-----------------+-----------+ | Prefix | YANG module | Reference | +--------+-----------------+-----------+ | yang | ietf-yang-types | [RFC6991] | | inet | ietf-inet-types | [RFC6991] | +--------+-----------------+-----------+ Table 1: Prefixes and corresponding YANG modules 4. Objectives This section describes some of the design objectives for the model: Pobbathi, et al. Expires April 12, 2015 [Page 4] Internet-Draft PCE-YANG October 2014 o In case of existing implementations, it needs to map the data model defined in this document to their proprietary native data model. To facilitate such mappings, the data model should be simple. o The data model should be suitable for new implementations to use as is. o Mapping to the PCEP MIB Module should be clear. o The data model should allow for static configurations of peers. o The data model should include read-only counters in order to gather statistics for sent and received PCEP messages, received messages with errors, and messages that could not be sent due to errors. o It should be fairly straight forward to augment the base data model for advanced PCE features. 5. The Design of PCEP Data Model The module, "ietf-pcep", defines the basic components of a PCE speaker. module ietf-pcep +--rw pcep | +--rw entity* [addr-type addr] | +--rw addr-type inet:ip-version | +--rw addr inet:ip-address | +--rw enabled? boolean | +--rw role pcep-role | +--rw description? string | +--rw connect-timer? uint32 | +--rw connect-max-retry? uint32 | +--rw init-backoff-timer? uint32 | +--rw max-backoff-timer? uint32 | +--rw open-wait-timer? uint32 | +--rw keep-wait-timer? uint32 | +--rw keep-alive-timer? uint32 | +--rw dead-timer? uint32 | +--rw allow-negotiation? boolean | +--rw max-keep-alive-timer? uint32 | +--rw max-dead-timer? uint32 | +--rw min-keep-alive-timer? uint32 | +--rw min-dead-timer? uint32 | +--rw sync-timer? uint32 | +--rw request-timer? uint32 Pobbathi, et al. Expires April 12, 2015 [Page 5] Internet-Draft PCE-YANG October 2014 | +--rw max-sessions? uint32 | +--rw max-unknown-reqs? uint32 | +--rw max-unknown-msgs? uint32 | +--rw peers | +--rw peer* [addr-type addr] | +--rw addr-type inet:ip-version | +--rw addr inet:ip-address | +--rw description? string +--ro pcep-state +--ro entity* [addr-type addr] +--ro index? uint32 +--ro addr-type inet:ip-version +--ro addr inet:ip-address +--ro admin-status? pcep-admin-status +--ro oper-status? pcep-admin-status +--ro role? pcep-role +--ro connect-timer? uint32 +--ro connect-max-retry? uint32 +--ro init-backoff-timer? uint32 +--ro max-backoff-timer? uint32 +--ro open-wait-timer? uint32 +--ro keep-wait-timer? uint32 +--ro keep-alive-timer? uint32 +--ro dead-timer? uint32 +--ro allow-negotiation? boolean +--ro max-keep-alive-timer? uint32 +--ro max-dead-timer? uint32 +--ro min-keep-alive-timer? uint32 +--ro min-dead-timer? uint32 +--ro sync-timer? uint32 +--ro request-timer? uint32 +--ro max-sessions? uint32 +--ro max-unknown-reqs? uint32 +--ro max-unknown-msgs? uint32 +--ro peers +--ro peer* [addr-type addr] +--ro addr-type inet:ip-version +--ro addr inet:ip-address +--ro role? pcep-role +--ro discontinuity-time? yang:timestamp +--ro initiate-session? boolean +--ro session-exists? boolean +--ro num-sess-setup-ok? yang:counter32 +--ro num-sess-setup-fail? yang:counter32 +--ro session-up-time? yang:timestamp +--ro session-fail-time? yang:timestamp +--ro session-fail-up-time? yang:timestamp +--ro avg-rsp-time? uint32 Pobbathi, et al. Expires April 12, 2015 [Page 6] Internet-Draft PCE-YANG October 2014 +--ro lwm-rsp-time? uint32 +--ro hwm-rsp-time? uint32 +--ro num-pcreq-sent? yang:counter32 +--ro num-pcreq-rcvd? yang:counter32 +--ro num-pcrep-sent? yang:counter32 +--ro num-pcrep-rcvd? yang:counter32 +--ro num-pcerr-sent? yang:counter32 +--ro num-pcerr-rcvd? yang:counter32 +--ro num-pcntf-sent? yang:counter32 +--ro num-pcntf-rcvd? yang:counter32 +--ro num-keepalive-sent? yang:counter32 +--ro num-keepalive-rcvd? yang:counter32 +--ro num-unknown-rcvd? yang:counter32 +--ro num-corrupt-rcvd? yang:counter32 +--ro num-req-sent? yang:counter32 +--ro num-svec-sent? yang:counter32 +--ro num-svec-req-sent? yang:counter32 +--ro num-req-sent-pend-rep? yang:counter32 +--ro num-req-sent-ero-rcvd? yang:counter32 +--ro num-req-sent-nopath-rcvd? yang:counter32 +--ro num-req-sent-cancel-rcvd? yang:counter32 +--ro num-req-sent-error-rcvd? yang:counter32 +--ro num-req-sent-timeout? yang:counter32 +--ro num-req-sent-cancel-sent? yang:counter32 +--ro num-req-rcvd? yang:counter32 +--ro num-svec-rcvd? yang:counter32 +--ro num-svec-req-rcvd? yang:counter32 +--ro num-req-rcvd-pend-rep? yang:counter32 +--ro num-req-rcvd-ero-sent? yang:counter32 +--ro num-req-rcvd-nopath-sent? yang:counter32 +--ro num-req-rcvd-cancel-sent? yang:counter32 +--ro num-req-rcvd-cancel-rcvd? yang:counter32 +--ro num-rep-rcvd-unknown? yang:counter32 +--ro num-req-rcvd-unknown? yang:counter32 +--ro num-req-sent-closed? yang:counter32 +--ro num-req-rcvd-closed? yang:counter32 +--ro sessions +--ro session* [initiator] +--ro initiator pcep-initiator +--ro state-last-change? yang:timestamp +--ro state? pcep-sess-state +--ro connect-retry? yang:counter32 +--ro local-id? uint32 +--ro remote-id? uint32 +--ro keepalive-timer? uint32 +--ro peer-keepalive-timer? uint32 +--ro dead-timer? uint32 +--ro peer-dead-timer? uint32 Pobbathi, et al. Expires April 12, 2015 [Page 7] Internet-Draft PCE-YANG October 2014 +--ro ka-hold-time-rem? uint32 +--ro overloaded? boolean +--ro overload-time? uint32 +--ro peer-overloaded? boolean +--ro peer-overload-time? uint32 +--ro discontinuity-time? yang:timestamp +--ro avg-rsp-time? uint32 +--ro lwm-rsp-time? uint32 +--ro hwm-rsp-time? uint32 +--ro num-pcreq-sent? yang:counter32 +--ro num-pcreq-rcvd? yang:counter32 +--ro num-pcrep-sent? yang:counter32 +--ro num-pcrep-rcvd? yang:counter32 +--ro num-pcerr-sent? yang:counter32 +--ro num-pcerr-rcvd? yang:counter32 +--ro num-pcntf-sent? yang:counter32 +--ro num-pcntf-rcvd? yang:counter32 +--ro num-keepalive-sent? yang:counter32 +--ro num-keepalive-rcvd? yang:counter32 +--ro num-unknown-rcvd? yang:counter32 +--ro num-corrupt-rcvd? yang:counter32 +--ro num-req-sent? yang:counter32 +--ro num-svec-sent? yang:counter32 +--ro num-svec-req-sent? yang:counter32 +--ro num-req-sent-pend-rep? yang:counter32 +--ro num-req-sent-ero-rcvd? yang:counter32 +--ro num-req-sent-nopath-rcvd? yang:counter32 +--ro num-req-sent-cancel-rcvd? yang:counter32 +--ro num-req-sent-error-rcvd? yang:counter32 +--ro num-req-sent-timeout? yang:counter32 +--ro num-req-sent-cancel-sent? yang:counter32 +--ro num-req-rcvd? yang:counter32 +--ro num-svec-rcvd? yang:counter32 +--ro num-svec-req-rcvd? yang:counter32 +--ro num-req-rcvd-pend-rep? yang:counter32 +--ro num-req-rcvd-ero-sent? yang:counter32 +--ro num-req-rcvd-nopath-sent? yang:counter32 +--ro num-req-rcvd-cancel-sent? yang:counter32 +--ro num-req-rcvd-cancel-rcvd? yang:counter32 +--ro num-rep-rcvd-unknown? yang:counter32 +--ro num-req-rcvd-unknown? yang:counter32 5.1. The Entity Lists The PCEP yang module may contain status information for multiple logical local PCEP entities. There are several scenarios in which there may be more than one local PCEP entity, it is listed in [I-D.ietf-pce-pcep-mib]. Pobbathi, et al. Expires April 12, 2015 [Page 8] Internet-Draft PCE-YANG October 2014 The data model for PCEP presented in this document uses a flat list of entities. Each entity in the list is identified by its IP address (addr-type, addr). Furthermore, each entity has a mandatory "role" leaf (the local entity PCEP role). The ietf-inet-types [RFC6991] is used. There is one list for configuration ("/pcep/entity"), and a separate list for the operational state of all entities ("/pcep-state/ entity"). The PCEP MIB module [I-D.ietf-pce-pcep-mib] uses a system generated entity index as a primary index to the read only entity table. If the device implements the PCEP MIB, the "index" leaf MUST contain the value of the corresponding pcePcepEntityIndex. 5.2. The Peer Lists The peer list contains peer that the local PCEP entity knows about. A PCEP speaker is identified by its IP address. If there is a PCEP speaker in the network that uses multiple IP addresses then it looks like multiple distinct peers to the other PCEP speakers in the network. Since PCEP sessions can be ephemeral, the peer list tracks a peer even when no PCEP session currently exists to that peer. The statistics contained are an aggregate of the statistics for all successive sessions to that peer. To limit the quantity of information that is stored, an implementation MAY choose to discard this information if and only if no PCEP session exists to the corresponding peer. The data model for PCEP peer presented in this document uses a flat list of peers. Each peer in the list is identified by its IP address (addr-type, addr). There is one list for static peer configuration ("/pcep/entity/ peers"), and a separate list for the operational state of all peers (i.e. static as well as discovered)("/pcep-state/entity/peers"). 5.3. The Session Lists The session list contains PCEP session that the PCEP entity (PCE or PCC) is currently participating in. The statistics in session are semantically different from those in peer since the former apply to the current session only, whereas the latter are the aggregate for all sessions that have existed to that peer. Pobbathi, et al. Expires April 12, 2015 [Page 9] Internet-Draft PCE-YANG October 2014 Although [RFC5440] forbids there from being more than one active PCEP session between a given pair of PCEP entities at any one time, there is a window during session establishment where two sessions may exist for a given peer, one representing a session initiated by the local PCEP entity and one representing a session initiated by the peer. If either of these sessions reaches active state, then the other is discarded. The data model for PCEP session presented in this document uses a flat list of sessions. Each session in the list is identified by its initiator. This index allows two sessions to exist transiently for a given peer, as discussed above. There is only one list for the operational state of all sessions ("/pcep-state/entity/peers/peer/sessions/session"). 6. Advanced PCE Features This document contains a specification of the base PCEP YANG module, "ietf-pcep" which provides the basic PCEP [RFC5440] data model. A means and procedure to handle to following PCE features needs to be decided: o Capability and Scope o Domain information (local/neighbour) o Path-Key o OF o GCO o P2MP o GMPLS o Inter-Layer o Stateful PCE 7. PCEP YANG Module RFC Ed.: In this section, replace all occurrences of 'XXXX' with the actual RFC number and all occurrences of the revision date below with the date of RFC publication (and remove this note). Pobbathi, et al. Expires April 12, 2015 [Page 10] Internet-Draft PCE-YANG October 2014 file "ietf-pcep@2014-10-09.yang" module ietf-pcep { namespace "urn:ietf:params:xml:ns:yang:ietf-pcep"; prefix pcep; import ietf-inet-types { prefix inet; } import ietf-yang-types { prefix yang; } organization "IETF PCE (Path Computation Element) Working Group"; contact "WG Web: WG List: WG Chair: JP Vasseur WG Chair: Julien Meuric Editor: Dhruv Dhody "; description "The YANG module defines a generic configuration and operational model for PCEP common across all of the vendor implementations."; revision 2014-10-09 { description "Initial revision."; reference "RFC XXXX: A YANG Data Model for Path Computation Element Communications Protocol (PCEP)"; } /* * Identities */ Pobbathi, et al. Expires April 12, 2015 [Page 11] Internet-Draft PCE-YANG October 2014 identity pcep { description "Identity for the PCEP protocol."; } /* * Typedefs */ typedef pcep-role { type enumeration { enum unknown { value "0"; description "An unknown role"; } enum pcc { value "1"; description "The role of a Path Computation Client"; } enum pce { value "2"; description "The role of Path Computation Element"; } enum pcc-and-pce { value "3"; description "The role of both Path Computation Client and Path Computation Element"; } } description "The role of a PCEP speaker. Takes one of the following values - unknown(0): the role is not known. - pcc(1): the role is of a Path Computation Client (PCC). - pce(2): the role is of a Path Computation Server (PCE). - pccAndPce(3): the role is of both a PCC and a PCE."; } typedef pcep-admin-status { type enumeration { enum admin-status-up { Pobbathi, et al. Expires April 12, 2015 [Page 12] Internet-Draft PCE-YANG October 2014 value "1"; description "Admin Status is Up"; } enum admin-status-down { value "2"; description "Admin Status is Down"; } } description "The Admin Status of the PCEP entity. Takes one of the following values - admin-status-up(1): Admin Status is Up. - admin-status-down(2): Admin Status is Down"; } typedef pcep-oper-status { type enumeration { enum oper-status-up { value "1"; description "The PCEP entity is active"; } enum oper-status-down { value "2"; description "The PCEP entity is inactive"; } enum oper-status-going-up { value "3"; description "The PCEP entity is activating"; } enum oper-status-going-down { value "4"; description "The PCEP entity is deactivating"; } enum oper-status-failed { value "5"; description "The PCEP entity has failed and will recover when possible."; } enum oper-status-failed-perm { value "6"; Pobbathi, et al. Expires April 12, 2015 [Page 13] Internet-Draft PCE-YANG October 2014 description "The PCEP entity has failed and will not recover without operator intervention"; } } description "The operational status of the PCEP entity. Takes one of the following values - oper-status-up(1): Active - oper-status-down(2): Inactive - oper-status-going-up(3): Activating - oper-status-going-down(4): Deactivating - oper-status-failed(5): Failed - oper-status-failed-perm(6): Failed Permanantly"; } typedef pcep-initiator { type enumeration { enum local { value "1"; description "The local PCEP entity initiated the session"; } enum remote { value "2"; description "The remote PCEP peer initiated the session"; } } description "The initiator of the session, that is, whether the TCP connection was initiated by the local PCEP entity or the remote peer. Takes one of the following values - local(1): Initiated locally - remote(2): Initiated remotely"; } typedef pcep-sess-state { type enumeration { enum tcp-pending { value "1"; description "The tcp-pending state of PCEP session."; } enum open-wait { Pobbathi, et al. Expires April 12, 2015 [Page 14] Internet-Draft PCE-YANG October 2014 value "2"; description "The open-wait state of PCEP session."; } enum keep-wait { value "3"; description "The keep-wait state of PCEP session."; } enum session-up { value "4"; description "The session-up state of PCEP session."; } } description "The current state of the session. The set of possible states excludes the idle state since entries do not exist in the idle state. Takes one of the following values - tcp-pending(1): PCEP TCP Pending state - open-wait(2): PCEP Open Wait state - keep-wait(3): PCEP Keep Wait state - session-up(4): PCEP Session Up state"; } /* * Features - TBD */ /* * Groupings */ grouping pcep-entity-identifier{ description "This grouping defines the identifier for PCEP entity."; leaf addr-type { type inet:ip-version; description "The type of the PCEP entity's Internet address. This object specifies how the value of the addr leaf should be interpreted."; } Pobbathi, et al. Expires April 12, 2015 [Page 15] Internet-Draft PCE-YANG October 2014 leaf addr { type inet:ip-address; description "The local Internet address of this PCEP entity. The type is given by addr-type. If operating as a PCE server, the PCEP entity listens on this address. If operating as a PCC, the PCEP entity binds outgoing TCP connections to this address. It is possible for the PCEP entity to operate both as a PCC and a PCE Server, in which case it uses this address both to listen for incoming TCP connections and to bind outgoing TCP connections."; } } grouping pcep-peer-identifier{ description "This grouping defines the identifier for PCEP peer."; leaf addr-type { type inet:ip-version; description "The type of the PCEP peer's Internet address. This object specifies how the value of the addr leaf should be interpreted."; } leaf addr { type inet:ip-address; description "The local Internet address of this PCEP peer. The type is given by addr-type."; } } grouping pcep-entity-info{ description "This grouping defines the attributes for PCEP entity."; leaf connect-timer { type uint32 { range "1..65535"; } units "seconds"; Pobbathi, et al. Expires April 12, 2015 [Page 16] Internet-Draft PCE-YANG October 2014 default 60; description "The time in seconds that the PCEP entity will wait to establish a TCP connection with a peer. If a TCP connection is not established within this time then PCEP aborts the session setup attempt."; reference "RFC 5440: Path Computation Element (PCE) Communication Protocol (PCEP)"; } leaf connect-max-retry { type uint32; default 5; description "The maximum number of times the system tries to establish a TCP connection to a peer before the session with the peer transitions to the idle state."; reference "RFC 5440: Path Computation Element (PCE) Communication Protocol (PCEP)"; } leaf init-backoff-timer { type uint32 { range "1..65535"; } units "seconds"; description "The initial back-off time in seconds for retrying a failed session setup attempt to a peer. The back-off time increases for each failed session setup attempt, until a maximum back-off time is reached. The maximum back-off time is max-backoff-timer."; } leaf max-backoff-timer { type uint32; units "seconds"; description "The maximum back-off time in seconds for retrying a failed session setup attempt to a peer. The back-off time increases for each failed session setup attempt, until this maximum value is reached. Pobbathi, et al. Expires April 12, 2015 [Page 17] Internet-Draft PCE-YANG October 2014 Session setup attempts then repeat periodically without any further increase in back-off time."; } leaf open-wait-timer { type uint32 { range "1..65535"; } units "seconds"; default 60; description "The time in seconds that the PCEP entity will wait to receive an Open message from a peer after the TCP connection has come up. If no Open message is received within this time then PCEP terminates the TCP connection and deletes the associated sessions."; reference "RFC 5440: Path Computation Element (PCE) Communication Protocol (PCEP)"; } leaf keep-wait-timer { type uint32 { range "1..65535"; } units "seconds"; default 60; description "The time in seconds that the PCEP entity will wait to receive a Keepalive or PCErr message from a peer during session initialization after receiving an Open message. If no Keepalive or PCErr message is received within this time then PCEP terminates the TCP connection and deletes the associated sessions."; reference "RFC 5440: Path Computation Element (PCE) Communication Protocol (PCEP)"; } leaf keep-alive-timer { type uint32 { range "0..255"; } units "seconds"; default 30; Pobbathi, et al. Expires April 12, 2015 [Page 18] Internet-Draft PCE-YANG October 2014 description "The keep alive transmission timer that this PCEP entity will propose in the initial OPEN message of each session it is involved in. This is the maximum time between two consecutive messages sent to a peer. Zero means that the PCEP entity prefers not to send Keepalives at all. Note that the actual Keepalive transmission intervals, in either direction of an active PCEP session, are determined by negotiation between the peers as specified by RFC 5440, and so may differ from this configured value."; reference "RFC 5440: Path Computation Element (PCE) Communication Protocol (PCEP)"; } leaf dead-timer { type uint32 { range "0..255"; } units "seconds"; must ". >= ../keep-alive-timer" { description "This value MUST be greater than keep-alive-timer."; } default 120; description "The dead timer that this PCEP entity will propose in the initial OPEN message of each session it is involved in. This is the time after which a peer should declare a session down if it does not receive any PCEP messages. Zero suggests that the peer does not run a dead timer at all." ; reference "RFC 5440: Path Computation Element (PCE) Communication Protocol (PCEP)"; } leaf allow-negotiation{ type boolean; description "Whether the PCEP entity will permit negotiation of session parameters."; } Pobbathi, et al. Expires April 12, 2015 [Page 19] Internet-Draft PCE-YANG October 2014 leaf max-keep-alive-timer{ type uint32 { range "0..255"; } units "seconds"; description "In PCEP session parameter negotiation in seconds, the maximum value that this PCEP entity will accept from a peer for the interval between Keepalive transmissions. Zero means that the PCEP entity will allow no Keepalive transmission at all." ; } leaf max-dead-timer{ type uint32 { range "0..255"; } units "seconds"; description "In PCEP session parameter negotiation in seconds, the maximum value that this PCEP entity will accept from a peer for the Dead timer. Zero means that the PCEP entity will allow not running a Dead timer."; } leaf min-keep-alive-timer{ type uint32 { range "0..255"; } units "seconds"; description "In PCEP session parameter negotiation in seconds, the minimum value that this PCEP entity will accept for the interval between Keepalive transmissions. Zero means that the PCEP entity insists on no Keepalive transmission at all."; } leaf min-dead-timer{ type uint32 { range "0..255"; } units "seconds"; description "In PCEP session parameter negotiationin in seconds, the minimum value that this PCEP entity Pobbathi, et al. Expires April 12, 2015 [Page 20] Internet-Draft PCE-YANG October 2014 will accept for the Dead timer. Zero means that the PCEP entity insists on not running a Dead timer."; } leaf sync-timer{ type uint32 { range "0..65535"; } units "seconds"; default 60; description "The value of SyncTimer in seconds is used in the case of synchronized path computation request using the SVEC object. Consider the case where a PCReq message is received by a PCE that contains the SVEC object referring to M synchronized path computation requests. If after the expiration of the SyncTimer all the M path computation requests have not been, received a protocol error is triggered and the PCE MUST cancel the whole set of path computation requests. The aim of the SyncTimer is to avoid the storage of unused synchronized requests should one of them get lost for some reasons (for example, a misbehaving PCC). Zero means that the PCEP entity does not use the SyncTimer."; reference "RFC 5440: Path Computation Element (PCE) Communication Protocol (PCEP)"; } leaf request-timer{ type uint32 { range "1..65535"; } units "seconds"; description "The maximum time that the PCEP entity will wait for a response to a PCReq message."; } leaf max-sessions{ type uint32; description Pobbathi, et al. Expires April 12, 2015 [Page 21] Internet-Draft PCE-YANG October 2014 "Maximum number of sessions involving this PCEP entity that can exist at any time."; } leaf max-unknown-reqs{ type uint32; default 5; description "The maximum number of unrecognized requests and replies that any session on this PCEP entity is willing to accept per minute before terminating the session. A PCRep message contains an unrecognized reply if it contains an RP object whose request ID does not correspond to any in-progress request sent by this PCEP entity. A PCReq message contains an unrecognized request if it contains an RP object whose request ID is zero."; reference "RFC 5440: Path Computation Element (PCE) Communication Protocol (PCEP)"; } leaf max-unknown-msgs{ type uint32; default 5; description "The maximum number of unknown messages that any session on this PCEP entity is willing to accept per minute before terminating the session."; reference "RFC 5440: Path Computation Element (PCE) Communication Protocol (PCEP)"; } }//pcep-entity-info grouping pcep-stats{ description "This grouping defines statistics for PCEP. It is used for both peer and current session."; leaf avg-rsp-time{ type uint32; units "milliseconds"; description "The average response time. Pobbathi, et al. Expires April 12, 2015 [Page 22] Internet-Draft PCE-YANG October 2014 If an average response time has not been calculated then this leaf has the value zero. If role is pcc then this leaf is meaningless and is set to zero."; } leaf lwm-rsp-time{ type uint32; units "milliseconds"; description "The smallest (low-water mark) response time seen. If no responses have been received then this leaf has the value zero. If role is pcc then this leaf is meaningless and is set to zero."; } leaf hwm-rsp-time{ type uint32; units "milliseconds"; description "The greatest (high-water mark) response time seen. If no responses have been received then this object has the value zero. If role is pcc then this field is meaningless and is set to zero."; } leaf num-pcreq-sent{ type yang:counter32; description "The number of PCReq messages sent."; } leaf num-pcreq-rcvd{ type yang:counter32; description "The number of PCReq messages received."; } leaf num-pcrep-sent{ type yang:counter32; description Pobbathi, et al. Expires April 12, 2015 [Page 23] Internet-Draft PCE-YANG October 2014 "The number of PCRep messages sent."; } leaf num-pcrep-rcvd{ type yang:counter32; description "The number of PCRep messages received."; } leaf num-pcerr-sent{ type yang:counter32; description "The number of PCErr messages sent."; } leaf num-pcerr-rcvd{ type yang:counter32; description "The number of PCErr messages received."; } leaf num-pcntf-sent{ type yang:counter32; description "The number of PCNtf messages sent."; } leaf num-pcntf-rcvd{ type yang:counter32; description "The number of PCNtf messages received."; } leaf num-keepalive-sent{ type yang:counter32; description "The number of Keepalive messages sent."; } leaf num-keepalive-rcvd{ type yang:counter32; description "The number of Keepalive messages received."; } leaf num-unknown-rcvd{ type yang:counter32; description Pobbathi, et al. Expires April 12, 2015 [Page 24] Internet-Draft PCE-YANG October 2014 "The number of unknown messages received."; } leaf num-corrupt-rcvd{ type yang:counter32; description "The number of corrupted PCEP message received."; } leaf num-req-sent{ type yang:counter32; description "The number of requests sent. A request corresponds 1:1 with an RP object in a PCReq message. This might be greater than num-pcreq-sent because multiple requests can be batched into a single PCReq message."; } leaf num-svec-sent{ type yang:counter32; description "The number of SVEC objects sent in PCReq messages. An SVEC object represents a set of synchronized requests."; } leaf num-svec-req-sent{ type yang:counter32; description "The number of requests sent that appeared in one or more SVEC objects."; } leaf num-req-sent-pend-rep{ type yang:counter32; description "The number of requests that have been sent for which a response is still pending."; } leaf num-req-sent-ero-rcvd{ type yang:counter32; description "The number of requests that have been sent for which a response with an ERO object was received. Such responses indicate that a path was successfully computed by the peer."; Pobbathi, et al. Expires April 12, 2015 [Page 25] Internet-Draft PCE-YANG October 2014 } leaf num-req-sent-nopath-rcvd{ type yang:counter32; description "The number of requests that have been sent for which a response with a NO-PATH object was received. Such responses indicate that the peer could not find a path to satisfy the request."; } leaf num-req-sent-cancel-rcvd{ type yang:counter32; description "The number of requests that were cancelled with a PCNtf message. This might be different than num-pcntf-rcvd because not all PCNtf messages are used to cancel requests, and a single PCNtf message can cancel multiple requests."; } leaf num-req-sent-error-rcvd{ type yang:counter32; description "The number of requests that were rejected with a PCErr message. This might be different than num-pcerr-rcvd because not all PCErr messages are used to reject requests, and a single PCErr message can reject multiple requests."; } leaf num-req-sent-timeout{ type yang:counter32; description "The number of requests that have been sent to a peer and have been abandoned because the peer has taken too long to respond to them."; } leaf num-req-sent-cancel-sent{ type yang:counter32; description "The number of requests that were sent to the peer and Pobbathi, et al. Expires April 12, 2015 [Page 26] Internet-Draft PCE-YANG October 2014 explicitly cancelled by the local PCEP entity sending a PCNtf."; } leaf num-req-rcvd{ type yang:counter32; description "The number of requests received. A request corresponds 1:1 with an RP object in a PCReq message. This might be greater than num-pcreq-rcvd because multiple requests can be batched into a single PCReq message."; } leaf num-svec-rcvd{ type yang:counter32; description "The number of SVEC objects received in PCReq messages. An SVEC object represents a set of synchronized requests."; } leaf num-svec-req-rcvd{ type yang:counter32; description "The number of requests received that appeared in one or more SVEC objects."; } leaf num-req-rcvd-pend-rep{ type yang:counter32; description "The number of requests that have been received for which a response is still pending."; } leaf num-req-rcvd-ero-sent{ type yang:counter32; description "The number of requests that have been received for which a response with an ERO object was sent. Such responses indicate that a path was successfully computed by the local PCEP entity."; } leaf num-req-rcvd-nopath-sent{ Pobbathi, et al. Expires April 12, 2015 [Page 27] Internet-Draft PCE-YANG October 2014 type yang:counter32; description "The number of requests that have been received for which a response with a NO-PATH object was sent. Such responses indicate that the local PCEP entity could not find a path to satisfy the request."; } leaf num-req-rcvd-cancel-sent{ type yang:counter32; description "The number of requests received that were cancelled by the local PCEP entity sending a PCNtf message. This might be different than num-pcntf-sent because not all PCNtf messages are used to cancel requests, and a single PCNtf message can cancel multiple requests."; } leaf num-req-rcvd-cancel-rcvd{ type yang:counter32; description "The number of requests that were received from the peer and explicitly cancelled by the peer sending a PCNtf."; } leaf num-rep-rcvd-unknown{ type yang:counter32; description "The number of responses to unknown requests received. A response to an unknown request is a response whose RP object does not contain the request ID of any request that is currently outstanding on the session."; } leaf num-req-rcvd-unknown{ type yang:counter32; description "The number of unknown requests that have been received. An unknown request is a request whose RP object contains a request ID of zero."; } }//pcep-stats Pobbathi, et al. Expires April 12, 2015 [Page 28] Internet-Draft PCE-YANG October 2014 /* * Configuration data nodes */ container pcep{ description "Parameters for list of configured PCEP entities on the device."; list entity{ key "addr-type addr"; description "The configured PCEP entity on the device."; uses pcep-entity-identifier { description "The configured PCEP entity Identifier."; } leaf enabled { type boolean; default true; description "The administrative status of this PCEP Entity."; } leaf role { type pcep-role; mandatory true; description "The role that this entity can play. Takes one of the following values. - unknown(0): this PCEP Entity role is not known. - pcc(1): this PCEP Entity is a PCC. - pce(2): this PCEP Entity is a PCE. - pcc-and-pce(3): this PCEP Entity is both a PCC and a PCE."; } leaf description { type string; description "Description of the PCEP entity configured by the user"; } Pobbathi, et al. Expires April 12, 2015 [Page 29] Internet-Draft PCE-YANG October 2014 uses pcep-entity-info { description "The configuration related to the PCEP entity."; } container peers{ description "The list of configured peers for the entity"; list peer{ key "addr-type addr"; description "The peer configured for the entity."; uses pcep-peer-identifier{ description "The configured PCEP peer's Identifier."; } leaf description { type string; description "Description of the PCEP peer configured by the user"; } }//peer }//peers }//entity }//pcep /* * Operational data nodes */ container pcep-state{ config false; description "The list of operational PCEP entities on the device."; list entity{ key "addr-type addr"; unique "index"; Pobbathi, et al. Expires April 12, 2015 [Page 30] Internet-Draft PCE-YANG October 2014 description "The operational PCEP entity on the device."; leaf index{ type uint32; description "The index of the PECP operational entity"; } uses pcep-entity-identifier { description "The PCEP entity Identifier."; } leaf admin-status { type pcep-admin-status; description "The administrative status of this PCEP Entity. This is the desired operational status as currently set by an operator or by default in the implementation. The value of enabled represents the current status of an attempt to reach this desired status."; } leaf oper-status { type pcep-admin-status; description "The operational status of the PCEP entity. Takes one of the following values. - oper-status-up(1): the PCEP entity is active. - oper-status-down(2): the PCEP entity is inactive. - oper-status-going-up(3): the PCEP entity is activating. - oper-status-going-down(4): the PCEP entity is deactivating. - oper-status-failed(5): the PCEP entity has failed and will recover when possible. - oper-status-failed-perm(6): the PCEP entity has failed and will not recover without operator intervention."; } leaf role { type pcep-role; Pobbathi, et al. Expires April 12, 2015 [Page 31] Internet-Draft PCE-YANG October 2014 description "The role that this entity can play. Takes one of the following values. - unknown(0): this PCEP entity role is not known. - pcc(1): this PCEP entity is a PCC. - pce(2): this PCEP entity is a PCE. - pcc-and-pce(3): this PCEP entity is both a PCC and a PCE."; } uses pcep-entity-info{ description "The operational information related to the PCEP entity."; } container peers{ description "The list of peers for the entity"; list peer{ key "addr-type addr"; description "The peer for the entity."; uses pcep-peer-identifier{ description "The PCEP peer's Identifier."; } leaf role { type pcep-role; description "The role of the PCEP Peer. Takes one of the following values. - unknown(0): this PCEP peer role is not known. - pcc(1): this PCEP peer is a PCC. - pce(2): this PCEP peer is a PCE. - pcc-and-pce(3): this PCEP peer is both a PCC and a PCE."; } leaf discontinuity-time { type yang:timestamp; Pobbathi, et al. Expires April 12, 2015 [Page 32] Internet-Draft PCE-YANG October 2014 description "The timestamp of the time when the information and statistics were last reset."; } leaf initiate-session { type boolean; description "Indicates whether the local PCEP entity initiates sessions to this peer, or waits for the peer to initiate a session."; } leaf session-exists{ type boolean; description "Indicates whether a session with this peer currently exists."; } leaf num-sess-setup-ok{ type yang:counter32; description "The number of PCEP sessions successfully successfully established with the peer, including any current session. This counter is incremented each time a session with this peer is successfully established."; } leaf num-sess-setup-fail{ type yang:counter32; description "The number of PCEP sessions with the peer that have been attempted but failed before being fully established. This counter is incremented each time a session retry to this peer fails."; } leaf session-up-time{ type yang:timestamp; description "The timestamp value of the last time a session with this peer was successfully Pobbathi, et al. Expires April 12, 2015 [Page 33] Internet-Draft PCE-YANG October 2014 established. If num-sess-setup-ok is zero, then this leaf contains zero."; } leaf session-fail-time{ type yang:timestamp; description "The timestamp value of the last time a session with this peer failed to be established. If num-sess-setup-fail is zero, then this leaf contains zero."; } leaf session-fail-up-time{ type yang:timestamp; description "The timestamp value of the last time a session with this peer failed from active. If num-sess-setup-ok is zero, then this leaf contains zero."; } uses pcep-stats{ description "Since PCEP sessions can be ephemeral, the peer statistics tracks a peer even when no PCEP session currently exists to that peer. The statistics contained are an aggregate of the statistics for all successive sessions to that peer."; } leaf num-req-sent-closed{ type yang:counter32; description "The number of requests that were sent to the peer and implicitly cancelled when the session they were sent over was closed."; } leaf num-req-rcvd-closed{ type yang:counter32; Pobbathi, et al. Expires April 12, 2015 [Page 34] Internet-Draft PCE-YANG October 2014 description "The number of requests that were received from the peer and implicitly cancelled when the session they were received over was closed."; } container sessions { description "This entry represents a single PCEP session in which the local PCEP entity participates. This entry exists only if the corresponding PCEP session has been initialized by some event, such as manual user configuration, auto- discovery of a peer, or an incoming TCP connection."; list session { key "initiator"; description "The list of sessions, note that for a time being two sessions may exist for a peer"; leaf initiator { type pcep-initiator; description "The initiator of the session, that is, whether the TCP connection was initiated by the local PCEP entity or the peer. There is a window during session initialization where two sessions can exist between a pair of PCEP speakers, each initiated by one of the speakers. One of these sessions is always discarded before it leaves OpenWait state. However, before it is discarded, two sessions to the given peer appear transiently in this MIB Pobbathi, et al. Expires April 12, 2015 [Page 35] Internet-Draft PCE-YANG October 2014 module. The sessions are distinguished by who initiated them, and so this field is the key."; } leaf state-last-change { type yang:timestamp; description "The timestamp value at the time this session entered its current state as denoted by the state leaf."; } leaf state { type pcep-sess-state; description "The current state of the session. The set of possible states excludes the idle state since entries do not exist in the idle state."; } leaf connect-retry { type yang:counter32; description "The number of times that the local PCEP entity has attempted to establish a TCP connection for this session without success. The PCEP entity gives up when this reaches connect-max-retry."; } leaf local-id { type uint32 { range "0..255"; } description "The value of the PCEP session ID used by the local PCEP entity in the Open message for this session. Pobbathi, et al. Expires April 12, 2015 [Page 36] Internet-Draft PCE-YANG October 2014 If state is tcp-pending then this is the session ID that will be used in the Open message. Otherwise, this is the session ID that was sent in the Open message."; } leaf remote-id { type uint32 { range "0..255"; } description "The value of the PCEP session ID used by the peer in its Open message for this session. If state is tcp-pending or open-wait then this leaf is not used and MUST be set to zero."; } leaf keepalive-timer { type uint32 { range "0..255"; } units "seconds"; description "The agreed maximum interval at which the local PCEP entity transmits PCEP messages on this PCEP session. Zero means that the local PCEP entity never sends Keepalives on this session. This field is used if and only if state is session-up. Otherwise, it is not used and MUST be set to zero."; } leaf peer-keepalive-timer { type uint32 { range "0..255"; } units "seconds"; Pobbathi, et al. Expires April 12, 2015 [Page 37] Internet-Draft PCE-YANG October 2014 description "The agreed maximum interval at which the peer transmits PCEP messages on this PCEP session. Zero means that the peer never sends Keepalives on this session. This field is used if and only if state is session-up. Otherwise, it is not used and MUST be set to zero."; } leaf dead-timer { type uint32 { range "0..255"; } units "seconds"; description "The dead timer interval for this PCEP session."; } leaf peer-dead-timer { type uint32 { range "0..255"; } units "seconds"; description "The peer's dead-timer interval for this PCEP session. If state is tcp-pending or open-wait then this leaf is not used and MUST be set to zero."; } leaf ka-hold-time-rem { type uint32 { range "0..255"; } units "seconds"; description "The keep alive hold time remaining for this session. Pobbathi, et al. Expires April 12, 2015 [Page 38] Internet-Draft PCE-YANG October 2014 If state is tcp-pending or open-wait then this field is not used and MUST be set to zero."; } leaf overloaded { type boolean; description "If the local PCEP entity has informed the peer that it is currently overloaded, then this is set to true. Otherwise, it is set to false."; } leaf overload-time { type uint32; units "seconds"; description "The interval of time that is remaining until the local PCEP entity will cease to be overloaded on this session. This field is only used if overloaded is set to true. Otherwise, it is not used and MUST be set to zero."; } leaf peer-overloaded { type boolean; description "If the peer has informed the local PCEP entity that it is currently overloaded, then this is set to true. Otherwise, it is set to false."; } leaf peer-overload-time { type uint32; units "seconds"; description "The interval of time that is remaining until the peer will cease to be overloaded. If it Pobbathi, et al. Expires April 12, 2015 [Page 39] Internet-Draft PCE-YANG October 2014 is not known how long the peer will stay in overloaded state, this leaf is set to zero. This field is only used if peer-overloaded is set to true. Otherwise, it is not used and MUST be set to zero."; } leaf discontinuity-time { type yang:timestamp; description "The timestamp value of the time when the statistics were last reset."; } uses pcep-stats{ description "The statistics contained are for the current sessions to that peer. These are lost when the session goes down."; } } // session } // sessions }//peer }//peers }//entity }//pcep-state }//module /* To Do - Notifications, rpc (if any) */ 8. Security Considerations This document does not add any new security concerns beyond those discussed in [RFC5440]. 9. Manageability Considerations Pobbathi, et al. Expires April 12, 2015 [Page 40] Internet-Draft PCE-YANG October 2014 9.1. Control of Function and Policy 9.2. Information and Data Models 9.3. Liveness Detection and Monitoring 9.4. Verify Correct Operations 9.5. Requirements On Other Protocols 9.6. Impact On Network Operations 10. IANA Considerations 11. Acknowledgements The initial document is based on the PCEP MIB [I-D.ietf-pce-pcep-mib]. Further this document structure is based on Routing Yang Module [I-D.ietf-netmod-routing-cfg]. We would like to thank the authors of aforementioned documents. 12. References 12.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC5440] Vasseur, JP. and JL. Le Roux, "Path Computation Element (PCE) Communication Protocol (PCEP)", RFC 5440, March 2009. [RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, October 2010. [RFC6991] Schoenwaelder, J., "Common YANG Data Types", RFC 6991, July 2013. 12.2. Informative References [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation Element (PCE)-Based Architecture", RFC 4655, August 2006. Pobbathi, et al. Expires April 12, 2015 [Page 41] Internet-Draft PCE-YANG October 2014 [I-D.ietf-pce-pcep-mib] Sreenivasa, K., Emile, S., Zhao, Q., King, D., and J. Hardwick, "Path Computation Element Communications Protocol (PCEP) Management Information Base (MIB) Module", draft-ietf-pce-pcep-mib-10 (work in progress), September 2014. [I-D.ietf-netmod-routing-cfg] Lhotka, L., "A YANG Data Model for Routing Management", draft-ietf-netmod-routing-cfg-15 (work in progress), May 2014. [I-D.ietf-netmod-rfc6087bis] Bierman, A., "Guidelines for Authors and Reviewers of YANG Data Model Documents", draft-ietf-netmod-rfc6087bis-00 (work in progress), June 2014. Pobbathi, et al. Expires April 12, 2015 [Page 42] Internet-Draft PCE-YANG October 2014 Appendix A. Contributor Addresses Young Lee Huawei Technologies 5340 Legacy Drive, Building 3 Plano, TX 75023, USA Phone: (469) 277-5838 EMail: leeyoung@huawei.com Udayasree Palle Huawei Technologies Leela Palace Bangalore, Karnataka 560008 India EMail: udayasree.palle@huawei.com Vishnu Pavan Beeram Juniper Networks USA EMail: vbeeram@juniper.net Authors' Addresses Rohit Pobbathi Huawei Technologies Leela Palace Bangalore, Karnataka 560008 India EMail: rohit.pobbathi@huawei.com Vinod KumarS Huawei Technologies Leela Palace Bangalore, Karnataka 560008 India EMail: vinods.kumar@huawei.com Pobbathi, et al. Expires April 12, 2015 [Page 43] Internet-Draft PCE-YANG October 2014 Dhruv Dhody (editor) Huawei Technologies Leela Palace Bangalore, Karnataka 560008 India EMail: dhruv.ietf@gmail.com Jonathan Hardwick Metaswitch 100 Church Street Enfield EN2 6BQ UK EMail: jonathan.hardwick@metaswitch.com Pobbathi, et al. Expires April 12, 2015 [Page 44]