ccamp W. Sun Internet-Draft SJTU Intended status: Standards Track G. Zhang Expires: May 22, 2008 CATR J. Gao Huawei G. Xie SJTU R. Papneja Isocore B. Gu IXIA X. Wei Fiberhome November 19, 2007 Label Switched Path (LSP) Dynamical Provisioning Performance Metrics in Generalized MPLS Networks draft-xie-ccamp-lsp-dppm-02.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. 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. Copyright Notice Sun, et al. Expires May 22, 2008 [Page 1] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 Copyright (C) The IETF Trust (2007). Sun, et al. Expires May 22, 2008 [Page 2] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 Abstract Generalized Multi-Protocol Label Switching (GMPLS) is one of the most promising candidate technologies for the future data transmission network. The GMPLS has been developed to control and cooperate different kinds of network elements, such as conventional routers, switches, Dense Wavelength Division Multiplexing (DWDM) systems, Add- Drop Multiplexors (ADMs), photonic cross-connects (PXCs), optical cross-connects (OXCs), etc. Dynamic provisioning ability of these physically diverse devices differs from each other drastically. At the same time, the need for dynamically provisioned connections is increasing because optical networks are being deployed in metro area. As different applications have varied requirements in the provisioning performance of optical networks, it is imperative to define standardized metrics and procedures such that the performance of networks and application needs can be mapped to each other. This document provides a series of performance metrics to evaluate the dynamic LSP provisioning performance in GMPLS networks, specifically the dynamical LSP setup/release performance. These metrics can depict the features of the GMPLS network in LSP dynamic provisioning. They can also be used in operational networks for carriers to monitor the control plane performance in realtime. Sun, et al. Expires May 22, 2008 [Page 3] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 6 2. Conventions Used in This Document . . . . . . . . . . . . . . 7 3. Overview of Performance Metrics . . . . . . . . . . . . . . . 8 4. A Singleton Definition for single unidirectional LSP Setup Delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 9 4.2. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 9 4.3. Metric Parameters . . . . . . . . . . . . . . . . . . . . 9 4.4. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 10 4.5. Definition . . . . . . . . . . . . . . . . . . . . . . . . 10 4.6. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 10 4.7. Methodologies . . . . . . . . . . . . . . . . . . . . . . 11 5. A Singleton Definition for multiple unidirectional LSP Setup Delay . . . . . . . . . . . . . . . . . . . . . . . . . 12 5.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 12 5.2. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 12 5.3. Metric Parameters . . . . . . . . . . . . . . . . . . . . 12 5.4. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 12 5.5. Definition . . . . . . . . . . . . . . . . . . . . . . . . 12 5.6. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 13 5.7. Methodologies . . . . . . . . . . . . . . . . . . . . . . 14 6. A Singleton Definition for single Bidirectional LSP Setup Delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 6.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 15 6.2. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 15 6.3. Metric Parameters . . . . . . . . . . . . . . . . . . . . 15 6.4. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 16 6.5. Definition . . . . . . . . . . . . . . . . . . . . . . . . 16 6.6. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 16 6.7. Methodologies . . . . . . . . . . . . . . . . . . . . . . 17 7. A Singleton Definition for multiple Bidirectional LSPs Setup Delay . . . . . . . . . . . . . . . . . . . . . . . . . 18 7.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 18 7.2. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 18 7.3. Metric Parameters . . . . . . . . . . . . . . . . . . . . 18 7.4. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 18 7.5. Definition . . . . . . . . . . . . . . . . . . . . . . . . 18 7.6. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 19 7.7. Methodologies . . . . . . . . . . . . . . . . . . . . . . 20 8. A Singleton Definition for LSP Graceful Release Delay . . . . 21 8.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 21 8.2. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 21 8.3. Metric Parameters . . . . . . . . . . . . . . . . . . . . 21 8.4. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 21 8.5. Definition . . . . . . . . . . . . . . . . . . . . . . . . 21 8.6. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 22 Sun, et al. Expires May 22, 2008 [Page 4] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 8.7. Methodologies . . . . . . . . . . . . . . . . . . . . . . 23 9. Typical Testing cases of single Unidirectional LSP Setup Delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 9.1. With no LSP in the Network . . . . . . . . . . . . . . . . 25 9.1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . 25 9.1.2. Methodologies . . . . . . . . . . . . . . . . . . . . 25 9.2. With a Number of LSPs in the Network . . . . . . . . . . . 25 9.2.1. Motivation . . . . . . . . . . . . . . . . . . . . . . 25 9.2.2. Methodologies . . . . . . . . . . . . . . . . . . . . 25 10. Typical Testing cases of multiple Unidirectional LSPs Setup Delay . . . . . . . . . . . . . . . . . . . . . . . . . 27 10.1. With no LSP in the Network . . . . . . . . . . . . . . . . 27 10.1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . 27 10.1.2. Methodologies . . . . . . . . . . . . . . . . . . . . 27 10.2. With a Number of LSPs in the Network . . . . . . . . . . . 27 10.2.1. Motivation . . . . . . . . . . . . . . . . . . . . . . 27 10.2.2. Methodologies . . . . . . . . . . . . . . . . . . . . 27 11. Typical Testing cases of single Bidirectional LSP Setup Delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 11.1. With no LSP in the Network . . . . . . . . . . . . . . . . 29 11.1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . 29 11.1.2. Methodologies . . . . . . . . . . . . . . . . . . . . 29 11.2. With a Number of LSPs in the Network . . . . . . . . . . . 29 11.2.1. Motivation . . . . . . . . . . . . . . . . . . . . . . 29 11.2.2. Methodologies . . . . . . . . . . . . . . . . . . . . 29 12. Typical Testing cases of multiple Bidirectional LSPs Setup Delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 12.1. With no LSP in the Network . . . . . . . . . . . . . . . . 31 12.1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . 31 12.1.2. Methodologies . . . . . . . . . . . . . . . . . . . . 31 12.2. With a Number of LSPs in the Network . . . . . . . . . . . 31 12.2.1. Motivation . . . . . . . . . . . . . . . . . . . . . . 31 12.2.2. Methodologies . . . . . . . . . . . . . . . . . . . . 31 13. Some Statistics Definitions for Metrics to Report . . . . . . 33 13.1. The Minimum of Metric . . . . . . . . . . . . . . . . . . 33 13.2. The Median of Metric . . . . . . . . . . . . . . . . . . . 33 13.3. The percentile of Metric . . . . . . . . . . . . . . . . . 33 13.4. The failure probability . . . . . . . . . . . . . . . . . 33 14. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 34 15. Security Considerations . . . . . . . . . . . . . . . . . . . 35 16. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 36 17. Normative References . . . . . . . . . . . . . . . . . . . . . 37 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 38 Intellectual Property and Copyright Statements . . . . . . . . . . 40 Sun, et al. Expires May 22, 2008 [Page 5] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 1. Introduction Generalized Multi-Protocol Label Switching (GMPLS) is one of the most promising control plane solutions for future transport and service network. GMPLS has been developed to control and cooperate different kinds of network elements, such as conventional routers, switches, Dense Wavelength Division Multiplexing (DWDM) systems, Add-Drop Multiplexors (ADMs), photonic cross-connects (PXCs), optical cross- connects (OXCs), etc. Dynamic provisioning ability of these physically diverse devices differs from each other drastically. The introduction of a control plane into optical circuit switching networks automates the provisioning of connections and drastically reduces connection provision delay. As more and more services and applications are seeking to use GMPLS controled networks as their underlying transport network, and increasingly in a dynamic way, the need is growing for measuring and characterizing the performance of LSP provisioning in GMPLS networks, such that requirement from applications and the provisioning capability of the network can be mapped to each other. This draft intends to define performance metrics and methodologies that can be used to depict the dynamic connection provisioning performance of GMPLS networks. The metrics defined in this draft can in the one hand be used to depict the averaged performance of GMPLS implementations. On the other hand, it can also be used in operational environments for carriers to monitor the control plane operation in realtime. For example, an new object can be added to the GMPLS TE STD MIB [RFC4802] such that the current and past control plane performance can be monitored through network management systems. The extension of TE-MIB to support the metrics defined is out the scope of this document. Sun, et al. Expires May 22, 2008 [Page 6] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 2. 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 [RFC2119]. Sun, et al. Expires May 22, 2008 [Page 7] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 3. Overview of Performance Metrics In this memo, to depict the dynamic LSP provisioning performance of a GMPLS network, we define 3 performance metrics: unidirectional LSP setup delay, bidirectional LSP setup delay, and LSP graceful release delay. The latency of the LSP setup/release signal is similar to the Round-trip Delay in IP networks. So we refer the structures and notions introduced and discussed in the IPPM Framework document, [RFC2330] [RFC2679] [RFC2681]. The reader is assumed to be familiar with the notions in those documents. Sun, et al. Expires May 22, 2008 [Page 8] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 4. A Singleton Definition for single unidirectional LSP Setup Delay This part defines a metric for single unidirectional Label Switched Path setup delay across a GMPLS network. 4.1. Motivation Single unidirectional Label Switched Path setup delay is useful for several reasons: o Single LSP setup delay is an important metric that depicts the provisioning performance of a GMPLS network. Longer LSP setup delay will incur higher overhead for the requesting application, especially when the LSP duration is comparable to the LSP setup delay. o The minimum value of this metric provides an indication of the delay that will likely be experienced when the LSP traversed the shortest route at the lightest load in the control plane. As the delay itself consists of several components, such as link propagation delay and nodal processing delay, this metric also reflects the status of control plane. For example, for LSPs traversing the same route, longer setup delays may suggest congestion in the control channel or high control element load. For this reason, this metric is useful for testing and diagnostic purposes. o LSP setup delay variance has different impact on to applications. Erratic variation in LSP setup delay makes it difficult to support applications that has stringent setup delay requirement. The measurement of single unidirectional LSP setup delay instead of bidirectional LSP setup delay is motivated by the following factors: o Some applications may only use unidirectional LSPs rather than bidirectional ones. For example, content delivery services in multicast method (IPTV) only use unidirectional LSPs. 4.2. Metric Name single unidirectional LSP setup delay 4.3. Metric Parameters o ID0, the ingress LSR ID o ID1, the egress LSR ID Sun, et al. Expires May 22, 2008 [Page 9] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 o T, a time 4.4. Metric Units The value of single unidirectional LSP setup delay is either a real number, or an undefined (informally, infinite) number of milliseconds. 4.5. Definition The single unidirectional LSP setup delay from the ingress node to the egress node [RFC3945] at T is dT means that ingress node sends the first bit of a PATH message packet to egress node at wire-time T, and that the ingress node received the last bit of responding RESV message packet from egress node at wire-time T+dT in the unidirectional LSP setup case. The single unidirectional LSP setup delay from the ingress node to the egress node at T is undefined (informally, infinite), means that ingress node sends the first bit of PATH message packet to egress node at wire-time T and that ingress node does not receive the corresponding RESV message within a reasonable period of time. 4.6. Discussion The following issues are likely to come up in practice: o The accuracy of unidirectional LSP setup delay at time T depends on the clock resolution in the ingress node; but synchronization between the ingress node and egress node is not required since unidirectional LSP setup uses two-way signaling. o A given methodology will have to include a way to determine whether a latency value is infinite or whether it is merely very large. Simple upper bounds could be used. But the GMPLS network accommodates many kinds of devices. For example, some photonic cross-connects (PXCs) have to move the micro mirrors. This physical motion may take several milliseconds. But the common electronic switches finish the nodal process within several microseconds. So the unidirectional LSP setup delay varies drastically from a network to another. In practice, the upper bound should be chosen carefully. o If ingress node sends out the PATH message to set up LSP, but never receive corresponding RESV message, unidirectional LSP setup delay is deemed to be infinite. Sun, et al. Expires May 22, 2008 [Page 10] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 o If ingress node sends out the PATH message to set up LSP but receive PathErr message, unidirectional LSP setup delay is also deemed to be infinite. There are many possible reasons for this case. For example, the PATH message has invalid parameters or the network has not enough resource to set up the requested LSP, etc. 4.7. Methodologies Generally the methodology would proceed as follows: o Make sure that the network has enough resource to set up the requested LSP. o At the ingress node, form the PATH message according to the LSP requirements. A timestamp (T1) may be stored locally in the ingress node when the PATH message packet is sent towards the egress node. o If the corresponding RESV message arrives within a reasonable period of time, take the timestamp (T2) as soon as possible upon receipt of the message. By subtracting the two timestamps, an estimate of unidirectional LSP setup delay (T2 -T1) can be computed. o If the corresponding RESV message fails to arrive within a reasonable period of time, the unidirectional LSP setup delay is deemed to be undefined (informally, infinite). Note that the 'reasonable' threshold of the unidirectional LSP setup delay is a parameter of the methodology. o If the corresponding response message is PathErr, the unidirectional LSP setup delay is deemed to be undefined (informally, infinite). Sun, et al. Expires May 22, 2008 [Page 11] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 5. A Singleton Definition for multiple unidirectional LSP Setup Delay This part defines a metric for multiple unidirectional Label Switched Paths setup delay across a GMPLS network. 5.1. Motivation multiple unidirectional Label Switched Paths setup delay is useful for several reasons: o Upon traffic interruption caused by network failure or network upgrade, carriers may require a large number of LSPs be set up during a short time period o The time needed to set up a large number of LSPs during a short time period can not be deduced by single LSP setup delay 5.2. Metric Name multiple unidirectional LSPs setup delay 5.3. Metric Parameters o ID0, the ingress LSR ID o ID1, the egress LSR ID o Lambda, a rate in reciprocal milliseconds o X, the number of LSPs to set up o T, a time 5.4. Metric Units The value of multiple unidirectional LSPs setup delay is either a real number, or an undefined (informally, infinite) number of milliseconds. 5.5. Definition Given lambda and X, the multiple unidirectional LSPs setup delay from the ingress node to the egress node [RFC3945] at T is dT means: o ingress node sends the first bit of the first PATH message packet to egress node at wire-time T Sun, et al. Expires May 22, 2008 [Page 12] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 o all subsequent (X-1) PATH messages are sent according to the specified poisson process with arrival rate lambda o ingress node receives all corresponding RESV message packets from egress node, and o ingress node receives the last RESV message packet at wire-time T+dT The multiple unidirectional LSPs setup delay at T is undefined (informally, infinite), means that ingress node sends all the PATH messages toward the egress and the first bit of the first PATH message packet is sent at wire-time T and that ingress node does not receive the one or more of the corresponding RESV messages within a reasonable period of time. 5.6. Discussion The following issues are likely to come up in practice: o The accuracy of multiple unidirectional LSPs setup delay at time T depends on the clock resolution in the ingress node; but synchronization between the ingress node and egress node is not required since unidirectional LSP setup uses two-way signaling. o A given methodology will have to include a way to determine whether a latency value is infinite or whether it is merely very large. Simple upper bounds could be used. But the GMPLS network accommodates many kinds of devices. For example, some photonic cross-connects (PXCs) have to move the micro mirrors. This physical motion may take several milliseconds. But the common electronic switches finish the nodal process within several microseconds. So the multiple unidirectional LSP setup delay varies drastically from a network to another. In practice, the upper bound should be chosen carefully. o If ingress node sends out the multiple PATH messages to set up the LSPs, but never receives one or more of the corresponding RESV messages, the unidirectional LSP setup delay is deemed to be infinite. o If ingress node sends out the PATH messages to set up the LSPs but receives one or more PathErr messages, multiple unidirectional LSPs setup delay is also deemed to be infinite. There are many possible reasons for this case. For example, one of the PATH message has invalid parameters or the network has not enough resource to set up the requested LSPs, etc. Sun, et al. Expires May 22, 2008 [Page 13] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 o The arrival rate of the poisson process lambda should be carefully chosen such that in the one hand the control plane is not overburdened.On the other hand, the arrival rate should also be large enough to meet the requirements of applications or services. 5.7. Methodologies Generally the methodology would proceed as follows: o Make sure that the network has enough resource to set up the requested LSPs. o At the ingress node, form the PATH messages according to the LSPs' requirements. o At the ingress node, select the time for each of the PATH messages according to the specified poisson process. o At the ingress node, sends out the PATH messages according to the selected time. o Store a timestamp (T1) locally in the ingress node when the first PATH message packet is sent towards the egress node. o If all of the corresponding RESV messages arrives within a reasonable period of time, take the final timestamp (T2) as soon as possible upon the receipt of all the messages. By subtracting the two timestamps, an estimate of multiple unidirectional LSPs setup delay (T2 -T1) can be computed. o If one or more of the corresponding RESV messages fails to arrive within a reasonable period of time, the multiple unidirectional LSPs setup delay is deemed to be undefined (informally, infinite). Note that the 'reasonable' threshold is a parameter of the methodology. o If one of the corresponding response message is PathErr, the multiple unidirectional LSPs setup delay is deemed to be undefined (informally, infinite). Sun, et al. Expires May 22, 2008 [Page 14] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 6. A Singleton Definition for single Bidirectional LSP Setup Delay GMPLS allows establishment of bi-directional symmetric LSPs (not of asymmetric LSPs). This part defines a metric for single bidirectional LSP setup delay across a GMPLS network. 6.1. Motivation Single bidirectional Label Switched Path setup delay is useful for several reasons: o LSP setup delay is an important metric that depicts the provisioning performance of a GMPLS network. Longer LSP setup delay will incur higher overhead for the requesting application, especially when the LSP duration is comparable to the LSP setup delay. Thus, measuring the setup delay is important for applications scheduling. o The minimum value of this metric provides an indication of the delay that will likely be experienced when the LSP traversed the shortest route at the lightest load in the control plane. As the delay itself consists of several components, such as link propagation delay and nodal processing delay, this metric also reflects the status of control plane. For example, for LSPs traversing the same route, longer setup delays may suggest congestion in the control channel or high control element load. For this reason, this metric is useful for testing and diagnostic purposes. o LSP setup delay variance has different impact on to applications. Erratic variation in LSP setup delay makes it difficult to support applications that has stringent setup delay requirement. The measurement of single bidirectional LSP setup delay instead of unidirectional LSP setup delay is motivated by the following factors: o Bidirectional LSPs are seen as a requirement for many GMPLS networks. Its provisioning performance is important to applications that generates bi-directional traffic. 6.2. Metric Name Single bidirectional LSP setup delay 6.3. Metric Parameters Sun, et al. Expires May 22, 2008 [Page 15] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 o ID0, the ingress LSR ID o ID1, the egress LSR ID o T, a time 6.4. Metric Units The value of single bidirectional LSP setup delay is either a real number, or an undefined (informally, infinite) number of milliseconds. 6.5. Definition For a real number dT, the single bidirectional LSP setup delay from ingress node to egress node at T is dT, means that ingress node sends out the first bit of a PATH message including an Upstream Label [RFC3473] heading for egress node at wire-time T, egress node receives that packet, then immediately sends a RESV message packet back to ingress node, and that ingress node receives the last bit of that packet at wire-time T+dT. The single bidirectional LSP setup delay from ingress node to egress node at T is undefined (informally, infinite), means that ingress node sends the first bit of PATH message to egress node at wire-time T and that ingress node does not receive that response packet. 6.6. Discussion The following issues are likely to come up in practice: o The accuracy of single bidirectional LSP setup delay depends on the clock resolution in the ingress node; but synchronization between the ingress node and egress node is not required since single bidirectional LSP setup uses two-way signaling. o A given methodology will have to include a way to determine whether a latency value is infinite or whether it is merely very large. Simple upper bounds could be used. But the GMPLS network accommodates many kinds of devices. For example, some photonic cross-connects (PXCs) have to move the micro mirrors. This physical motion may take several milliseconds. But the common electronic switches finish the nodal process within several microseconds. So the bidirectional LSP setup delay varies drastically from a network to another. In the process of bidirectional LSP setup, if the downstream node overrides the label suggested by the upstream node, the setup delay will also increase obviously. Thus, in practice, the upper bound should be Sun, et al. Expires May 22, 2008 [Page 16] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 chosen carefully. o If the ingress node sends out the PATH message to set up the LSP, but never receives the corresponding RESV message, single bidirectional LSP setup delay is deemed to be infinite. o If the ingress node sends out the PATH message to set up the LSP, but receives PathErr message, single bidirectional LSP setup delay is also deemed to be infinite. There are many possible reasons for this case. For example, the PATH message has invalid parameters or the network has not enough resource to set up the requested LSP. 6.7. Methodologies Generally the methodology would proceed as follows: o Make sure that the network has enough resource to set up the requested LSP. o At the ingress node, form the PATH message (including the Upstream Label or suggested label) according to the LSP requirements. A timestamp (T1) may be stored locally in the ingress node when the PATH message packet is sent towards the egress node. o If the corresponding RESV message arrives within a reasonable period of time, take the final timestamp (T2) as soon as possible upon the receipt of the message. By subtracting the two timestamps, an estimate of bidirectional LSP setup delay (T2 -T1) can be computed. o If the corresponding RESV message fails to arrive within a reasonable period of time, the single bidirectional LSP setup delay is deemed to be undefined (informally, infinite). Note that the 'reasonable' threshold is a parameter of the methodology. o If the corresponding response message is PathErr, the single bidirectional LSP setup delay is deemed to be undefined (informally, infinite). Sun, et al. Expires May 22, 2008 [Page 17] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 7. A Singleton Definition for multiple Bidirectional LSPs Setup Delay This part defines a metric for multiple bidirectional LSPs setup delay across a GMPLS network. 7.1. Motivation multiple Bidirectional LSPs setup delay is useful for several reasons: o Upon traffic interruption caused by network failure or network upgrade, carriers may require a large number of LSPs be set up during a short time period o The time needed to setup a large number of LSPs during a short time period can not be deduced by single LSP setup delay 7.2. Metric Name Multiple bidirectional LSPs setup delay 7.3. Metric Parameters o ID0, the ingress LSR ID o ID1, the egress LSR ID o Lambda, a rate in reciprocal milliseconds o X, the number of LSPs to setup o T, a time 7.4. Metric Units The value of multiple bidirectional LSPs setup delay is either a real number, or an undefined (informally, infinite) number of milliseconds. 7.5. Definition Given lambda and X, for a real number dT, the multiple bidirectional LSPs setup delay from ingress node to egress node at T is dT, means that: o ingress node sends the first bit of the first PATH message heading for egress node at wire-time T Sun, et al. Expires May 22, 2008 [Page 18] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 o all subsequent (X-1) PATH messages are sent according to the specified poisson process with arrival rate lambda o ingress node receives all corresponding RESV message packets from egress node, and o ingress node receives the last RESV message packets at wire-time T+dT The multiple bidirectional LSPs setup delay from ingress node to egress node at T is undefined (informally, infinite), means that ingress node sends all the PATH messages to egress node and that the ingress node dose not receive one or more of the response messages. 7.6. Discussion The following issues are likely to come up in practice: o The accuracy of multiple bidirectional LSPs setup delay depends on the clock resolution in the ingress node; but synchronization between the ingress node and egress node is not required since bidirectional LSP setup uses two-way signaling. o A given methodology will have to include a way to determine whether a latency value is infinite or whether it is merely very large. Simple upper bounds could be used. But the GMPLS network accommodates many kinds of devices. For example, some photonic cross-connects (PXCs) have to move the micro mirrors. This physical motion may take several milliseconds. But the common electronic switches finish the nodal process within several microseconds. So the bidirectional LSP setup delay varies drastically from a network to another. In the process of bidirectional LSP setup, if the downstream node overrides the label suggested by the upstream node, the setup delay will also increase obviously. Thus, in practice, the upper bound should be chosen carefully. o If the ingress node sends out the PATH messages to set up the LSPs, but never receive all the corresponding RESV messages, the multiple bidirectional LSPs setup delay is deemed to be infinite. o If the ingress node sends out the PATH messages to set up the LSPs, but receive one or more responding PathErr messages,the multiple bidirectional LSPs setup delay is also deemed to be infinite. There are many possible reasons for this case. For example, one or more of the PATH messages have invalid parameters or the network has not enough resource to set up the requested LSPs. Sun, et al. Expires May 22, 2008 [Page 19] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 o The arrival rate of the poisson process lambda should be carefully chosen such that in the one hand the control plane is not overburdened.On the other hand, the arrival rate should also be large enough to meet the requirements of applications or services. 7.7. Methodologies Generally the methodology would proceed as follows: o Make sure that the network has enough resource to set up the requested LSPs. o At the ingress node, form the PATH messages (including the Upstream Label or suggested label) according to the LSPs' requirements. o At the ingress node, select the time for each of the PATH messages according to the specified poisson process. o At the ingress node, sends out the PATH messages according to the selected time. o Store a timestamp (T1) locally in the ingress node when the first PATH message packet is sent towards the egress node. o If all of the corresponding RESV messages arrives within a reasonable period of time, take the final timestamp (T2) as soon as possible upon the receipt of all the messages. By subtracting the two timestamps, an estimate of multiple bidirectional LSPs setup delay (T2 -T1) can be computed. o If one or more of the corresponding RESV messages fails to arrive within a reasonable period of time, the multiple bidirectional LSPs setup delay is deemed to be undefined (informally, infinite). Note that the 'reasonable' threshold is a parameter of the methodology. o If one or more of the corresponding response messages is PathErr, the multiple bidirectional LSPs setup delay is deemed to be undefined (informally, infinite). Sun, et al. Expires May 22, 2008 [Page 20] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 8. A Singleton Definition for LSP Graceful Release Delay There are two different kinds of LSP release mechanisms in the GMPLS network: graceful release and forceful release. Memo in current version has not taken forceful LSP release procedure into account. 8.1. Motivation LSP graceful release delay is useful for several reasons: o The LSP graceful release delay is part of the total cost of dynamic LSP provisioning. For some short duration applications, the LSP tear down time can not be ignored o The LSP graceful release procedure is more prefered in a GMPLS controled network, particularly the optical networks. Since it doesn't trigger restoration/protection, it is "alarm-free connection deletion" in [RFC4208]. 8.2. Metric Name LSP graceful release delay 8.3. Metric Parameters o ID0, the ingress LSR ID o ID1, the egress LSR ID o T, a time 8.4. Metric Units The value of LSP graceful release delay is either a real number, or an undefined (informally, infinite) number of milliseconds. 8.5. Definition There are two different LSP graceful release procedures, one is initiated by the ingress node, and another is initiated by egress node. The two procedures are depicted in the [RFC3473]. We define the graceful LSP release delay for these two procedures separately. For a real number dT, the LSP graceful release delay from ingress node to egress node at T is dT, means that ingress node sends the first bit of a PATH message including Admin Status Object with setting the Reflect (R) and Delete (D) bits to egress node at wire- time T, that egress node receives that packet, then immediately sends Sun, et al. Expires May 22, 2008 [Page 21] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 a RESV message including Admin Status Object with the Delete (D) bit set back to ingress node. The ingress node sends out PathTear downstream to remove the LSP, and egress node receives the last bit of PathTear packet at wire-time T+dT. Also as an option, upon receipt of the PATH message including Admin Status Object with setting the Reflect (R) and Delete (D) bits, the egress node may respond with PathErr message with the Path_State_Removed flag set. The LSP graceful release delay from ingress node to egress node at T is undefined (informally, infinite), means that ingress node sends the first bit of PATH message to egress node at wire-time T and that (either egress node does not receive the PATH packet, egress node does not send corresponding RESV message packet in response, ingress node does not receive that RESV packet, or) the egress does not receive the PathTear. The LSP graceful release delay from egress node to ingress node at T is dT, means that egress node sends the first bit of a RESV message including Admin Status Object with setting the Reflect (R) and Delete (D) bits to ingress node at wire-time T. The ingress node sends out PathTear downstream to remove the LSP, and egress node receives the last bit of PathTear packet at wire-time T+dT. The LSP graceful release delay from egress node to ingress node at T is undefined (informally, infinite), means that egress node sends the first bit of RESV message including Admin Status Object with setting the Reflect (R) and Delete (D) bits to ingress node at wire-time T and that (either ingress node does not receive the RESV packet, ingress node does not send PathTear message packet in response or) the egress does not receive the PathTear. 8.6. Discussion The following issues are likely to come up in practice: o In the first (second) circumstance, the accuracy of LSP graceful release delay at time T depends on the clock resolution in the ingress (egress) node. In the first circumstance, synchronization between the ingress node and egress node is required; but not in the second circumstance; o A given methodology has to include a way to determine whether a latency value is infinite or whether it is merely very large. Simple upper bounds could be used. But the upper bound should be chosen carefully in practice; Sun, et al. Expires May 22, 2008 [Page 22] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 o In the first circumstance, if ingress node sends out PATH message including Admin Status Object with the Reflect (R) and Delete (D) bits set to initiate LSP graceful release, but never receive corresponding RESV message, LSP graceful release delay is deemed to be infinite. In the second circumstance, if egress node sends out RESV message including Admin Status Object with the Reflect (R) and Delete (D) bits set to initiate LSP graceful release, but never receive corresponding PathTear message, LSP graceful release delay is deemed to be infinite; 8.7. Methodologies In the first circumstance, the methodology may proceed as follows: o Make sure the LSP to be deleted is set up; o At the egress node, form the PATH message including Admin Status Object with the Reflect (R) and Delete (D) bits set. A timestamp (T1) may be stored locally in the ingress node when the PATH message packet is sent towards the egress node; o Upon receiving the PATH message including Admin Status Object with the Reflect (R) and Delete (D) bits set, the egress node sends a RESV message including Admin Status Object with the Delete (D) and Reflect (R) bits set. Or, alternatively, the egress node sends a PathErr message with the Path_State_Removed flag set upstream; o When the ingress node receive the RESV message or the PathErr message, it sends a PathTear message to remove the LSP; o Egress node takes a timestamp (T2) once it receives the last bit of the PathTear message. The LSP graceful release delay is then (T2-T1). In the second circumstance, the methodology would proceed as follows: o Make sure the LSP to be deleted is set up; o On the egress node, form the RESV message including Admin Status Object with the Reflect (R) and Delete (D) bits set. A timestamp may be stored locally in the egress node when the RESV message packet is sent towards the ingress node; o Upon receiving the Admin Status Object with the Reflect (R) and Delete (D) bits set in the RESV message, the ingress node sends a PathTear message downstream to remove the LSP; Sun, et al. Expires May 22, 2008 [Page 23] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 o Egress node takes a timestamp (T2) once it receives the last bit of the PathTear message. The LSP graceful release delay is then (T2-T1). Sun, et al. Expires May 22, 2008 [Page 24] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 9. Typical Testing cases of single Unidirectional LSP Setup Delay Now we define typical test cases of getting unidirectional LSP setup delay. 9.1. With no LSP in the Network 9.1.1. Motivation Single unidirectional LSP setup delay with no LSP in the network is important because this reflects the inherent delay of an RSVP-TE implementation. The minimum value provides an indication of the delay that will likely be experienced when an LSP traverses the shortest route with the lightest load in the control plane. 9.1.2. Methodologies Make sure that there is no or very few LSPs in the network. The methodology would proceed as follows: o Set up the LSP using the methodology for the singleton single unidirectional LSP setup delay, and obtain the value of unidirectional LSP setup delay o Release the LSP o Repeat this process if multiple samples are needed Note that: in case multiple samples are to be obtained, the interval between each process should be large enough to guarantee the network has already reached a stable state. 9.2. With a Number of LSPs in the Network 9.2.1. Motivation Single unidirectional LSP setup delay with a number of LSPs in the network is important because it reflects the performance of an operational network with considrable load. This delay can vary significantly as the number of existing LSPs vary. It can be used as a scalability metric of an RSVP-TE implementation. 9.2.2. Methodologies Setup the required number of LSPs, and wait until the network reaches a stable state, then proceed as follows: Sun, et al. Expires May 22, 2008 [Page 25] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 o Set up the LSP using the methodology for the singleton single unidirectional LSP setup delay, and obtain the value of unidirectional LSP setup delay o Release the LSP o Repeat this process if multiple samples are needed Note that: in case multiple samples are to be obtained, the interval between each process should be large enough to guarantee the network has already reached a stable state. Sun, et al. Expires May 22, 2008 [Page 26] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 10. Typical Testing cases of multiple Unidirectional LSPs Setup Delay Now we define typical test cases of getting multiple unidirectional LSPs setup delay. 10.1. With no LSP in the Network 10.1.1. Motivation multiple unidirectional LSP setup delay with no LSP in the network is important because this reflects the inherent delay of an RSVP-TE implementation. The minimum value provides an indication of the delay that will likely be experienced when a number of LSPs are set up with the lightest load in the control plane. 10.1.2. Methodologies Make sure that there is no or very few LSPs in the network. The methodology would proceed as follows: o Set up the LSPs using the methodology for the singleton multiple unidirectional LSP setup delay, and obtain the value of multiple unidirectional LSP setup delay o Release the LSPs o Repeat this process if multiple samples are needed Note that: in case multiple samples are to be obtained, the interval between each process should be large enough to guarantee the network has already reached a stable state. 10.2. With a Number of LSPs in the Network 10.2.1. Motivation multiple unidirectional LSP setup delay with a number of LSPs in the network is important because it reflects the performance of an operational network with considrable load. This delay can vary significantly as the number of existing LSPs vary. It can be used as a scalability metric of an RSVP-TE implementation. 10.2.2. Methodologies Setup the required number of LSPs, and wait until the network reaches a stable state, then proceed as follows: Sun, et al. Expires May 22, 2008 [Page 27] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 o Set up the LSPs using the methodology for the singleton multiple unidirectional LSP setup delay, and obtain the value of multiple unidirectional LSP setup delay o Release the LSPs o Repeat this process if multiple samples are needed Note that: in case multiple samples are to be obtained, the interval between each process should be large enough to guarantee the network has already reached a stable state. Sun, et al. Expires May 22, 2008 [Page 28] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 11. Typical Testing cases of single Bidirectional LSP Setup Delay Now we define typical test cases of getting single bidirectional LSP setup delay. 11.1. With no LSP in the Network 11.1.1. Motivation Single unidirectional LSP setup delay with no LSP in the network is important because this reflects the inherent delay of an RSVP-TE implementation. The minimum value provides an indication of the delay that will likely be experienced when an LSP traverses the shortest route with the lightest load in the control plane. 11.1.2. Methodologies Make sure that there is no or very few LSPs in the network. The methodology would proceed as follows: o Set up the LSP using the methodology for the singleton bidirectional LSP setup delay, and obtain the value of unidirectional LSP setup delay o Release the LSP o Repeat this process if multiple samples are needed Note that: in case multiple samples are to be obtained, the interval between each process should be large enough to guarantee the network has already reached a stable state. 11.2. With a Number of LSPs in the Network 11.2.1. Motivation Single bidirectional LSP setup delay with a number of LSPs in the network is important because it reflects the performance of an operational network with considrable load. This delay can vary significantly as the number of existing LSPs vary. It can be used as a scalability metric of an RSVP-TE implementation. 11.2.2. Methodologies Setup the required number of LSPs, and wait until the network reaches a stable state, then proceed as follows: Sun, et al. Expires May 22, 2008 [Page 29] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 o Set up the LSP using the methodology for the singleton bidirectional bidirectional LSP setup delay, and obtain the value of bidirectional LSP setup delay o Release the LSP o Repeat this process if multiple samples are needed Note that: in case multiple samples are to be obtained, the interval between each process should be large enough to guarantee the network has already reached a stable state. Sun, et al. Expires May 22, 2008 [Page 30] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 12. Typical Testing cases of multiple Bidirectional LSPs Setup Delay Now we define typical test cases of getting multiple bidirectional LSPs setup delay. 12.1. With no LSP in the Network 12.1.1. Motivation multiple bidirectional LSP setup delay with no LSP in the network is important because this reflects the inherent delay of an RSVP-TE implementation. The minimum value provides an indication of the delay that will likely be experienced when a number of LSPs are setup with the lightest load in the control plane. 12.1.2. Methodologies Make sure that there is no or very few LSPs in the network. The methodology would proceed as follows: o Set up the LSPs using the methodology for the singleton multiple multiple bidirectional LSP setup delay, and obtain the value of multiple bidirectional LSP setup delay o Release the LSPs o Repeat this process if multiple samples are needed Note that: in case multiple samples are to be obtained, the interval between each process should be large enough to guarantee the network has already reached a stable state. 12.2. With a Number of LSPs in the Network 12.2.1. Motivation multiple bidirectional LSPs setup delay with a number of LSPs in the network is important because it reflects the performance of an operational network with considrable load. This delay can vary significantly as the number of existing LSPs vary. It can be used as a scalability metric of an RSVP-TE implementation. 12.2.2. Methodologies Setup the required number of LSPs, and wait until the network reaches a stable state, then proceed as follows: Sun, et al. Expires May 22, 2008 [Page 31] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 o Set up the LSPs using the methodology for the singleton multiple bidirectional LSPs setup delay, and obtain the value of multiple bidirectional LSPs setup delay o Release the LSPs o Repeat this process if multiple samples are needed Note that: in case multiple samples are to be obtained, the interval between each process should be large enough to guarantee the network has already reached a stable state. Sun, et al. Expires May 22, 2008 [Page 32] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 13. Some Statistics Definitions for Metrics to Report Given the samples of the performance metric, we now offer several statistics of these samples to report. From these statistics, we can draw some useful conclusions of a GMPLS network. The value of these metrics is either a real number, or an undefined (informally, infinite) number of milliseconds. In the following discussion, we only consider the finite values. 13.1. The Minimum of Metric The minimum of metric is the minimum of all the dT values in the sample. In computing this, undefined values are treated as infinitely large. Note that this means that the minimum could thus be undefined (informally, infinite) if all the dT values are undefined. In addition, the metric minimum is undefined if the sample is empty. 13.2. The Median of Metric Metric median is the median of the dT values in the given sample. In computing the median, the undefined values are not counted in. 13.3. The percentile of Metric Given a metric and a percent X between 0% and 100%, the Xth percentile of all the dT values in the sample. In addition, the unidirectional LSP setup delay percentile is undefined if the sample is empty. Example: suppose we take a sample and the results are: Stream1 = < , , , , > Then the 50th percentile would be 110 msec, since 90 msec and 100 msec are smaller, and 110 and 500 msec are larger (undefined values are not counted in). 13.4. The failure probability In the process of LSP setup/release, it may fail for some reason. The failure probability is the ratio of the failure times to the total times. Sun, et al. Expires May 22, 2008 [Page 33] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 14. Discussion It is worthwhile to point out that: o The unidirectional/bidirectional LSP setup delay is one ingress- egress round trip time plus processing time. But in the draft, unidirectional/bidirectional LSP setup delay has not taken the processing time in the end nodes (ingress or/and egress) into account. The timestamp T2 is taken after the endpoint node receives it. Actually, the last node has to take some time to process local procedure. Similarly, in the LSP graceful release delay, the memo has not considered the processing time in the endpoint node. o All these metrics are defined from the point of control plane's view. In fact, the control plane and data plane are not always synchronized. In some cases, the LSPs have been set up in the control plane. But the data can not be forwarded immediately. The unidirectional/bidirectional LSP setup delay in the data plane is longer than in the control plane. Sun, et al. Expires May 22, 2008 [Page 34] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 15. Security Considerations The security considerations pertaining to the original RSVP protocol [RFC2205] and its TE extensions [RFC3209] remain relevant. Sun, et al. Expires May 22, 2008 [Page 35] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 16. Acknowledgements We wish to thank Dan Li, Fang Liu (Christine), Zafar Ali, Monique Morrow, Al Morton, Adrian Farrel, Deborah Brungard, Thomas D. Nadeau for their comments and helps. This document contains ideas as well as text that have appeared in existing IETF documents. The authors wish to thank G. Almes, S. Kalidindi and M. Zekauskas. We also wish to thank Weisheng Hu, Yaohui Jin and Wei Guo in the state key laboratory of advanced optical communication systems and networks for the valuable comments. We also wish to thank the support from NSFC and 863 program of China. Sun, et al. Expires May 22, 2008 [Page 36] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 17. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S. Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 Functional Specification", RFC 2205, September 1997. [RFC2330] Paxson, V., Almes, G., Mahdavi, J., and M. Mathis, "Framework for IP Performance Metrics", RFC 2330, May 1998. [RFC2679] Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way Delay Metric for IPPM", RFC 2679, September 1999. [RFC2681] Almes, G., Kalidindi, S., and M. Zekauskas, "A Round-trip Delay Metric for IPPM", RFC 2681, September 1999. [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels", RFC 3209, December 2001. [RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions", RFC 3473, January 2003. [RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching (GMPLS) Architecture", RFC 3945, October 2004. [RFC4208] Swallow, G., Drake, J., Ishimatsu, H., and Y. Rekhter, "Generalized Multiprotocol Label Switching (GMPLS) User- Network Interface (UNI): Resource ReserVation Protocol- Traffic Engineering (RSVP-TE) Support for the Overlay Model", RFC 4208, October 2005. [RFC4802] Nadeau, T. and A. Farrel, "Generalized Multiprotocol Label Switching (GMPLS) Traffic Engineering Management Information Base", RFC 4802, February 2007. Sun, et al. Expires May 22, 2008 [Page 37] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 Authors' Addresses Weiqiang Sun Shanghai Jiao Tong University 800 Dongchuan Road Shanghai 200240 CN Phone: +86 21 3420 5359 Email: sunwq@sjtu.edu.cn Guoying Zhang China Academy of Telecommunication Research,MII. Beijing 200240 CN Phone: +86 1068094272 Email: zhangguoying@mail.ritt.com.cn Jianhua Gao Huawei Technologies Co., LTD. CN Phone: +86 755 28973237 Email: gjhhit@huawei.com Guowu Xie Shanghai Jiao Tong University 800 Dongchuan Road Shanghai 200240 CN Phone: +86 21 3420 4596 Email: blithe@sjtu.edu.cn Rajiv Papneja Isocore 12359 Sunrise Valley Drive, STE 100 Reston, VA 20190 USA Phone: +1 703 860 9273 Email: rpapneja@isocore.com Sun, et al. Expires May 22, 2008 [Page 38] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 Bin Gu IXIA Oriental Kenzo Plaza 8M,48 Dongzhimen Wai Street,Dongcheng District Beijing 200240 CN Phone: +86 13611590766 Email: BGu@ixiacom.com Xueqing Wei Fiberhome Telecommunicaiton Technology Co.,Ltd. Wuhan CN Phone: +86 13871127882 Email: xqwei@fiberhome.com.cn Sun, et al. Expires May 22, 2008 [Page 39] Internet-Draft LSP Dynamical PPM in GMPLS Networks November 2007 Full Copyright Statement Copyright (C) The IETF Trust (2007). 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The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgement Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Sun, et al. Expires May 22, 2008 [Page 40]