draft-ietf-ccamp-gr-description-00.txt   draft-ietf-ccamp-gr-description-01.txt 
Network Working Group Dan Li Network Working Group Dan Li
Internet Draft Jianhua Gao Internet Draft Jianhua Gao
Huawei Huawei
Arun Satyanarayana Arun Satyanarayana
Cisco Cisco
Intended Status: Informational Intended Status: Informational
Expires: February 2008 August, 2007 Expires: May 2008 November, 2007
Description of the RSVP-TE Graceful Restart Procedures Description of the RSVP-TE Graceful Restart Procedures
draft-ietf-ccamp-gr-description-00.txt draft-ietf-ccamp-gr-description-01.txt
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware 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 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. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
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the nodes restart is different. the nodes restart is different.
This document does not define any new processes or procedures. All This document does not define any new processes or procedures. All
protocol mechanisms are already defined in the referenced documents. protocol mechanisms are already defined in the referenced documents.
Table of Contents Table of Contents
1. Introduction.................................................3 1. Introduction.................................................3
2. Existing Procedures for Single Node Restart..................4 2. Existing Procedures for Single Node Restart..................4
2.1. Procedures defined in [RFC3473]............................4 2.1. Procedures defined in [RFC3473]............................4
2.2. Procedures defined in [GR-EXT].............................5 2.2. Procedures defined in [RFC5063]............................5
3. Multiple Node Restart Scenarios..............................5 3. Multiple Node Restart Scenarios..............................5
4. RSVP State...................................................6 4. RSVP State...................................................6
5. Procedures for Multiple Node Restart.........................7 5. Procedures for Multiple Node Restart.........................7
5.1. Procedures for the Normal Node.............................7 5.1. Procedures for the Normal Node.............................7
5.2. Procedures for the Restarting Node.........................7 5.2. Procedures for the Restarting Node.........................7
5.2.1. Procedures for Scenario 1................................7 5.2.1. Procedures for Scenario 1................................7
5.2.2. Procedures for Scenario 2................................9 5.2.2. Procedures for Scenario 2................................9
5.2.3. Procedures for scenario 3...............................10 5.2.3. Procedures for scenario 3...............................10
5.2.4. Procedures for scenario 4...............................11 5.2.4. Procedures for scenario 4...............................11
5.2.5. Procedures for scenario 5...............................11 5.2.5. Procedures for scenario 5...............................11
5.3. Consideration of Re-Use of Data Plane Resources...........12 5.3. Consideration of Re-Use of Data Plane Resources...........12
5.4. Consideration of Management Plane Intervention............12 5.4. Consideration of Management Plane Intervention............12
6. Security Considerations.....................................12 6. Clarification of Restarting Node Procedure..................12
7. IANA Considerations.........................................13 7. Security Considerations.....................................14
8. Acknowledgments.............................................13 8. IANA Considerations.........................................14
9. References..................................................13 9. Acknowledgments.............................................14
9.1. Normative References......................................13 10. References.................................................15
10. Authors' Addresses.........................................14 10.1. Normative References.....................................15
11. Full Copyright Statement...................................14 11. Authors' Addresses.........................................16
12. Intellectual Property Statement............................15 12. Full Copyright Statement...................................16
13. Intellectual Property Statement............................17
1. Introduction 1. Introduction
The Hello message for the Resource Reservation Protocol (RSVP) has The Hello message for the Resource Reservation Protocol (RSVP) has
been defined to establish and maintain basic signaling node been defined to establish and maintain basic signaling node
adjacencies for Label Switching Routers (LSRs) participating in a adjacencies for Label Switching Routers (LSRs) participating in a
Multiprotocol Label Switching (MPLS) traffic engineered (TE) Multiprotocol Label Switching (MPLS) traffic engineered (TE)
network [RFC3209]. The Hello message has been extended for use in network [RFC3209]. The Hello message has been extended for use in
Generalized MPLS (GMPLS) network for state recovery of control Generalized MPLS (GMPLS) network for state recovery of control
channel or nodal faults through the exchange of the Restart channel or nodal faults through the exchange of the Restart
Capabilities object [RFC3473]. Capabilities object [RFC3473].
GMPLS protocol definitions for RSVP [RFC3473] also allow a GMPLS protocol definitions for RSVP [RFC3473] also allow a
restarting node to learn the label that it previously allocated for restarting node to learn the label that it previously allocated for
use on a Label Switching Path (LSP) through the Recovery Label use on a Label Switching Path (LSP) through the Recovery Label
object carried on a Path message sent to a restarting node from its object carried on a Path message sent to a restarting node from its
upstream neighbor. upstream neighbor.
Further RSVP protocol extensions have been defined [GR-EXT] to Further RSVP protocol extensions have been defined [RFC5063] to
perform graceful restart and to enable a restarting node to recover perform graceful restart and to enable a restarting node to recover
full control plane state by exchanging RSVP messages with its full control plane state by exchanging RSVP messages with its
upstream and downstream neighbors. State previously transmitted to upstream and downstream neighbors. State previously transmitted to
the upstream neighbor (principally the downstream label) is the upstream neighbor (principally the downstream label) is
recovered from the upstream neighbor on a Path message (using the recovered from the upstream neighbor on a Path message (using the
Recovery Label object as described in [RFC3473]). State previously Recovery Label object as described in [RFC3473]). State previously
transmitted to the downstream neighbor (including the upstream transmitted to the downstream neighbor (including the upstream
label, interface identifiers, and the explicit route) is recovered label, interface identifiers, and the explicit route) is recovered
from the downstream neighbor using a RecoveryPath message. from the downstream neighbor using a RecoveryPath message.
[GR-EXT] also extends the Hello message to exchange information [RFC5063] also extends the Hello message to exchange information
about the ability to support the RecoveryPath message. about the ability to support the RecoveryPath message.
The examples and procedures in [RFC3473] and [GR-EXT] focus on the The examples and procedures in [RFC3473] and [RFC5063] focus on the
description of a single node restart when adjacent network nodes description of a single node restart when adjacent network nodes
are operative. Although the procedures are equally applicable to are operative. Although the procedures are equally applicable to
multi-node restarts, no detailed explanation is provided. multi-node restarts, no detailed explanation is provided.
This document provides and informational clarification of the This document provides and informational clarification of the
control plane procedures for a GMPLS network when there are control plane procedures for a GMPLS network when there are
multiple node failures, and describes how full control plane state multiple node failures, and describes how full control plane state
can be recovered in different scenarios where the order in which can be recovered in different scenarios where the order in which
the nodes restart is different. the nodes restart is different.
This document does not define any new processes or procedures. All This document does not define any new processes or procedures. All
protocol mechanisms already defined in [RFC3473] and [GR-EXT] are protocol mechanisms already defined in [RFC3473] and [RFC5063] are
definitive. definitive.
2. Existing Procedures for Single Node Restart 2. Existing Procedures for Single Node Restart
This section documents for information the existing procedures This section documents for information the existing procedures
defined in [RFC3473] and [GR-EXT]. Those documents are definitive, defined in [RFC3473] and [RFC5063]. Those documents are definitive,
and the description here is non-normative. It is provided for and the description here is non-normative. It is provided for
informational clarification only. informational clarification only.
2.1. Procedures defined in [RFC3473] 2.1. Procedures defined in [RFC3473]
In the case of nodal faults, the procedures for the restarting node In the case of nodal faults, the procedures for the restarting node
and the procedures for the neighbor of a restarting node are and the procedures for the neighbor of a restarting node are
applied to the corresponding nodes. These procedures described in applied to the corresponding nodes. These procedures described in
[RFC3473] are summarized as follows: [RFC3473] are summarized as follows:
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For the Neighbor of a restarting node: For the Neighbor of a restarting node:
1) Sends the Path message with RECOVERY_LABEL object containing a 1) Sends the Path message with RECOVERY_LABEL object containing a
label value corresponding to the label value received in the most label value corresponding to the label value received in the most
recently received corresponding Resv message; recently received corresponding Resv message;
2) Resumes refreshing Path state with the restarting node; 2) Resumes refreshing Path state with the restarting node;
3) Resumes refreshing Resv state with the restarting node. 3) Resumes refreshing Resv state with the restarting node.
2.2. Procedures defined in [GR-EXT] 2.2. Procedures defined in [RFC5063]
A new message is introduced in [GR-EXT] which is called the A new message is introduced in [RFC5063] which is called the
RecoveryPath message. The message is sent by the downstream RecoveryPath message. The message is sent by the downstream
neighbor of a restarting node to convey the contents of the last neighbor of a restarting node to convey the contents of the last
received Path message back to the restarting node. received Path message back to the restarting node.
The restarting node will receive the Path message with the The restarting node will receive the Path message with the
RECOVERY_LABEL object from its upstream neighbor, and/or the RECOVERY_LABEL object from its upstream neighbor, and/or the
RecoveryPath message from its downstream neighbor. The full RSVP RecoveryPath message from its downstream neighbor. The full RSVP
state of the restarting node can be recovered from these two state of the restarting node can be recovered from these two
messages. messages.
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the PSB is responsible for receiving a Path from upstream and the PSB is responsible for receiving a Path from upstream and
sending a Path to downstream. sending a Path to downstream.
Regardless of how the RSVP state is implemented, on recovery there Regardless of how the RSVP state is implemented, on recovery there
are two logical pieces of state to be recovered and these are two logical pieces of state to be recovered and these
correspond to the PSB and RSB. correspond to the PSB and RSB.
5. Procedures for Multiple Node Restart 5. Procedures for Multiple Node Restart
In this document, all the nodes are assumed to have the graceful In this document, all the nodes are assumed to have the graceful
restart capabilities which are described in [RFC3473] and [GR-EXT]. restart capabilities which are described in [RFC3473] and [RFC5063].
5.1. Procedures for the Normal Node 5.1. Procedures for the Normal Node
When the downstream Normal node detects its neighbor restarting, it When the downstream Normal node detects its neighbor restarting, it
must send a RecoveryPath message for each LSP associated with the must send a RecoveryPath message for each LSP associated with the
restarting node for which it has previously sent a Resv message and restarting node for which it has previously sent a Resv message and
which has not been torn down. which has not been torn down.
When the upstream Normal node detects its neighbor restarting, it When the upstream Normal node detects its neighbor restarting, it
must send a Path message with RECOVERY_LABEL object containing a must send a Path message with RECOVERY_LABEL object containing a
label value corresponding to the label value received in the most label value corresponding to the label value received in the most
recently received corresponding Resv message. recently received corresponding Resv message.
This document does not modify the procedures for the Normal node This document does not modify the procedures for the Normal node
which are described in [RFC3473] and [GR-EXT]. which are described in [RFC3473] and [RFC5063].
5.2. Procedures for the Restarting Node 5.2. Procedures for the Restarting Node
This document does not modify the procedures for the Restarting This document does not modify the procedures for the Restarting
node which are described in [RFC3473] and [GR-EXT]. node which are described in [RFC3473] and [RFC5063].
5.2.1. Procedures for Scenario 1 5.2.1. Procedures for Scenario 1
After the Restarting node restarts, it starts a Recovery Timer. Any After the Restarting node restarts, it starts a Recovery Timer. Any
RSVP state that has not been resynchronized when the Recovery Timer RSVP state that has not been resynchronized when the Recovery Timer
expires, should be cleared. expires, should be cleared.
At the Restarting node (Node B in the example), full At the Restarting node (Node B in the example), full
resynchronization with the upstream neighbor (Node A) is possible resynchronization with the upstream neighbor (Node A) is possible
because Node A is a Normal node. The upstream Path information is because Node A is a Normal node. The upstream Path information is
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message received from Node A, but, obviously, some information message received from Node A, but, obviously, some information
(like the Recorded Route Object) will be missing from the new Resv (like the Recorded Route Object) will be missing from the new Resv
message generated by Node B, and can not be supplied until the message generated by Node B, and can not be supplied until the
downstream Delayed Restarting node (Node C) restarts and sends a downstream Delayed Restarting node (Node C) restarts and sends a
Resv. Resv.
After the upstream Path information and upstream Resv information After the upstream Path information and upstream Resv information
has been recovered by Node B, the normal refresh procedure with the has been recovered by Node B, the normal refresh procedure with the
upstream Node A should be started. upstream Node A should be started.
As per [GR-EXT], the Restarting node (Node B) would normally expect As per [RFC5063], the Restarting node (Node B) would normally
to receive a RecoveryPath message from its downstream neighbor expect to receive a RecoveryPath message from its downstream
(Node C). It would use this to recover the downstream Path neighbor (Node C). It would use this to recover the downstream Path
information, and would subsequently send a Path message to its information, and would subsequently send a Path message to its
downstream neighbor and receive a Resv message. But in this downstream neighbor and receive a Resv message. But in this
scenario, because the downstream neighbor has not restarted yet, scenario, because the downstream neighbor has not restarted yet,
Node B detects the communication with Node C is interrupted and Node B detects the communication with Node C is interrupted and
must wait before resynchronizing with its downstream neighbor. must wait before resynchronizing with its downstream neighbor.
In this case, the Restarting node (Node B) follows the procedures In this case, the Restarting node (Node B) follows the procedures
in section 9.3 of [RFC3473] and may run a Restart Timer to wait for in section 9.3 of [RFC3473] and may run a Restart Timer to wait for
the downstream neighbor (Node C) to restart. If its downstream the downstream neighbor (Node C) to restart. If its downstream
neighbor (Node C) has not restarted before the timer expires the neighbor (Node C) has not restarted before the timer expires the
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plane and the data plane on the nodes that are waiting for the plane and the data plane on the nodes that are waiting for the
failed device to restart. failed device to restart.
If the downstream Delayed Restarting node restarts after the If the downstream Delayed Restarting node restarts after the
cleanup of LSPs at Node C, the RecoveryPath message from Node D cleanup of LSPs at Node C, the RecoveryPath message from Node D
will be responded with a PathTear message. If the upstream Delayed will be responded with a PathTear message. If the upstream Delayed
Restarting node restarts after the cleanup of LSPs at Node C, the Restarting node restarts after the cleanup of LSPs at Node C, the
Path message from Node B will be treated as a new LSP setup request, Path message from Node B will be treated as a new LSP setup request,
but the setup will fail because Node D cannot be reached - Node C but the setup will fail because Node D cannot be reached - Node C
will respond with a PathErr message. Since this happens to Node B will respond with a PathErr message. Since this happens to Node B
during its restart processing, it should follow the rules of [GR- during its restart processing, it should follow the rules of
EXT] and tear down the LSP. [RFC5063] and tear down the LSP.
5.2.4. Procedures for scenario 4 5.2.4. Procedures for scenario 4
When the Ingress node (Node A) restarts, it does not know which When the Ingress node (Node A) restarts, it does not know which
LSPs it caused to be created. Usually, however, this information is LSPs it caused to be created. Usually, however, this information is
retrieved from the management plane or from the configuration retrieved from the management plane or from the configuration
requests stored in non-volatile form in the node in order to requests stored in non-volatile form in the node in order to
recover the LSP state. recover the LSP state.
Furthermore, if the downstream node (Node B) is a Normal node, Furthermore, if the downstream node (Node B) is a Normal node,
according to the procedures in [GR-EXT], the ingress will receive a according to the procedures in [RFC5063], the ingress will receive
RecoveryPath message and will understand that it was the ingress of a RecoveryPath message and will understand that it was the ingress
the LSP. of the LSP.
However, in this scenario, the downstream node is a Delayed However, in this scenario, the downstream node is a Delayed
Restarting node, so Node A must rely on the information from the Restarting node, so Node A must rely on the information from the
management plane or stored configuration, or it must wait for Node management plane or stored configuration, or it must wait for Node
B to restart. B to restart.
In the event that Node B never restarts, management plane In the event that Node B never restarts, management plane
intervention may be used at Node A to clean up any LSP state intervention may be used at Node A to clean up any LSP state
restored from the management plane or from local configuration. restored from the management plane or from local configuration.
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plane resources and to over-ride the control plane. In this context, plane resources and to over-ride the control plane. In this context,
the management plane must always be able to release data plane the management plane must always be able to release data plane
resources that were previously in place for use by control-plane resources that were previously in place for use by control-plane
established LSPs. Further, the management plane must always be able established LSPs. Further, the management plane must always be able
to instruct any control plane node to tear down any LSP. to instruct any control plane node to tear down any LSP.
Operators should be aware of the risks of misconnection that could Operators should be aware of the risks of misconnection that could
be caused by careless manipulation from the management plane of in- be caused by careless manipulation from the management plane of in-
use data plane resources. use data plane resources.
6. Security Considerations 6. Clarification of Restarting Node Procedure
According to the current graceful restart procedure [RFC3473],
after a node restarts its control plane, it needs its upstream node
to send PATH message with recovery label to synchronize its RSVP
state. If the restarted control plane becomes operational quickly,
the upstream node may not detect the restarting of downstream node
and therefore, may send a PATH message without recovery label
causing errors and unwanted connection deletion.
N1 N2
| |
| X (Restart start)
| HELLO |
|--------------->|
| |
| SRefresh |
|--------------->|
| |
| HELLO |
|--------------->|
| |
| X (Restart complete)
| SRefresh |
|--------------->|
| NACK |
|<---------------|
| Path without |
| recovery label |
|--------------->|
| X (resoure allocation failed because the
| | resouces are in use)
| PathErr |
|<---------------|
| PathTear |
|--------------->|
X(CON deletion) X (XCON deletion)
| |
The sequence diagram above depicts one scenario where the LSP may
get deleted.
In this sequence N1 did not detect hello failure and continues
sending SRefreshes which may get NACK'ed by N2 once restart
completes because there is no Path state corresponding to the
SRefresh message. This NACK causes a Path refresh message to be
generated but there is no RECOVERY_LABEL because N1 did not yet
detect that N2 has restarted as hello exchanges have not yet
started. The Path message is treated as "new" and fails to allocate
the resources because they are still in use. This causes a PathErr
message to be generated which may lead to the tear down of the LSP.
To resolve the aforementioned problem, the following procedures are
proposed and are meant to work together with the recovery
procedures documented in [RFC3473]. Here, it is assumed that the
restarting node and the neighboring node(s) support Hello extension
as documented in [RFC3209] and recovery procedures documented in
[RFC3473].
After a node restarts its control plane, it should ignore and
silently drop all RSVP-TE messages, except hello messages, it
receives from any neighbor to which, no HELLO session has been
established.
The restarting node should follow [RFC3209] to establish Hello
sessions with its neighbors, after its control plane becomes
operational.
The restarting node resumes processing of RSVP-TE messages sent
from each neighbor to which the Hello session has been established.
7. Security Considerations
This document clarifies the procedures to be performed on RSVP This document clarifies the procedures to be performed on RSVP
agents that neighbor one or more restarting RSVP agents. In the agents that neighbor one or more restarting RSVP agents. In the
case of the control plane in general, and the RSVP agent in case of the control plane in general, and the RSVP agent in
particular, where one or more nodes carrying one or more LSPs are particular, where one or more nodes carrying one or more LSPs are
restarted due to external attacks, the procedures defined in [GR- restarted due to external attacks, the procedures defined in
EXT] and described in this document provide the ability for the [RFC5063] and described in this document provide the ability for
restarting RSVP agents to recover the RSVP state in each restarting the restarting RSVP agents to recover the RSVP state in each
node corresponding to the LSPs, with the least possible restarting node corresponding to the LSPs, with the least possible
perturbation to the rest of the network. Ideally, only the perturbation to the rest of the network. Ideally, only the
neighboring RSVP agents should notice the restart and hence need to neighboring RSVP agents should notice the restart and hence need to
perform additional processing. This allows for a network with perform additional processing. This allows for a network with
active LSPs to recover LSP state gracefully from an external attack, active LSPs to recover LSP state gracefully from an external attack,
without perturbing the data/forwarding plane state. without perturbing the data/forwarding plane state.
7. IANA Considerations 8. IANA Considerations
This document defines no new protocols or extensions and makes no This document defines no new protocols or extensions and makes no
requests to IANA for registry management. requests to IANA for registry management.
8. Acknowledgments 9. Acknowledgments
We would like to thank Adrian Farrel, Dimitri Papadimitriou, and We would like to thank Adrian Farrel, Dimitri Papadimitriou, and
Lou Berger for their useful comments. Lou Berger for their useful comments.
9. References 10. References
9.1. Normative References 10.1. Normative References
[RFC2209] R. Braden, L. Zhang, "Resource ReSerVation Protocol [RFC2209] R. Braden, L. Zhang, "Resource ReSerVation Protocol (RSVP)
(RSVP) -- Version 1 Message Processing Rules", RFC 2209, -- Version 1 Message Processing Rules", RFC 2209, September
September 1997. 1997.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
V., and G. Swallow, "RSVP-TE: Extensions to RSVP for and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
LSP Tunnels", RFC 3209, December 2001. Tunnels", RFC 3209, December 2001.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching [RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic (GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.
2003.
[GR-EXT] A. Satyanarayana, R. Rahman, "Extensions to GMPLS RSVP [RFC5063] A. Satyanarayana, R. Rahman, "Extensions to GMPLS RSVP
Graceful Restart", Internet Draft, work in progress, Graceful Restart", RFC 5063, September 2007.
draft-ietf-ccamp-rsvp-restart-ext-08.txt, January 2007.
10. Authors' Addresses 11. Authors' Addresses
Dan Li Dan Li
Huawei Technologies Co., Ltd. Huawei Technologies Co., Ltd.
F3-5-B R&D Center, Huawei Base, F3-5-B R&D Center, Huawei Base,
Bantian, Longgang District Bantian, Longgang District
Shenzhen 518129 P.R.China Shenzhen 518129 P.R.China
Phone: +86-755-28972910 Phone: +86-755-28972910
Email: danli@huawei.com Email: danli@huawei.com
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Email: gjhhit@huawei.com Email: gjhhit@huawei.com
Arun Satyanarayana Arun Satyanarayana
Cisco Systems, Inc. Cisco Systems, Inc.
170 West Tasman Dr. 170 West Tasman Dr.
San Jose, CA 95134, USA San Jose, CA 95134, USA
Phone: +1 408 853-3206 Phone: +1 408 853-3206
Email: asatyana@cisco.com Email: asatyana@cisco.com
11. Full Copyright Statement Snigdho C. Bardalai
Fujitsu Network Communications, Inc.
2801 Telecom Parkway,
Richardson, Texas 75082
United States of America
Phone: +1 972 479 2951
Email: snigdho.bardalai@us.fujitsu.com
12. Full Copyright Statement
Copyright (C) The IETF Trust (2007). Copyright (C) The IETF Trust (2007).
This document is subject to the rights, licenses and restrictions This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors contained in BCP 78, and except as set forth therein, the authors
retain all their rights. retain all their rights.
This document and the information contained herein are provided on This document and the information contained herein are provided on
an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE
IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL
WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY
WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE
ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS
FOR A PARTICULAR PURPOSE. FOR A PARTICULAR PURPOSE.
12. Intellectual Property Statement 13. Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed Intellectual Property Rights or other rights that might be claimed
to pertain to the implementation or use of the technology described to pertain to the implementation or use of the technology described
in this document or the extent to which any license under such in this document or the extent to which any license under such
rights might or might not be available; nor does it represent that rights might or might not be available; nor does it represent that
it has made any independent effort to identify any such rights. it has made any independent effort to identify any such rights.
Information on the procedures with respect to rights in RFC Information on the procedures with respect to rights in RFC
documents can be found in BCP 78 and BCP 79. documents can be found in BCP 78 and BCP 79.
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