draft-ietf-forces-ceha-06.txt   draft-ietf-forces-ceha-07.txt 
Network Working Group K. Ogawa Network Working Group K. Ogawa
Internet-Draft NTT Corporation Internet-Draft NTT Corporation
Intended status: Standards Track W. M. Wang Intended status: Standards Track W. M. Wang
Expires: August 23, 2013 Zhejiang Gongshang University Expires: November 09, 2013 Zhejiang Gongshang University
E. Haleplidis E. Haleplidis
University of Patras University of Patras
J. Hadi Salim J. Hadi Salim
Mojatatu Networks Mojatatu Networks
February 19, 2013 May 08, 2013
ForCES Intra-NE High Availability ForCES Intra-NE High Availability
draft-ietf-forces-ceha-06 draft-ietf-forces-ceha-07
Abstract Abstract
This document discusses CE High Availability within a ForCES NE. This document discusses Control Element High Availability within a
ForCES Network Element.
Status of this Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
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time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
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This Internet-Draft will expire on August 23, 2013. This Internet-Draft will expire on November 09, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Document Scope . . . . . . . . . . . . . . . . . . . . . . 5 2.1. Document Scope . . . . . . . . . . . . . . . . . . . . . 5
2.2. Quantifying Problem Scope . . . . . . . . . . . . . . . . 5 2.2. Quantifying Problem Scope . . . . . . . . . . . . . . . . 5
3. RFC5810 CE HA Framework . . . . . . . . . . . . . . . . . . . 6 3. RFC5810 CE HA Framework . . . . . . . . . . . . . . . . . . . 6
3.1. RFC 5810 CE High Availability Support . . . . . . . . . . 6 3.1. RFC 5810 CE HA Support . . . . . . . . . . . . . . . . . 6
3.1.1. Cold Standby Interaction with ForCES Protocol . . . . 7 3.1.1. Cold Standby Interaction with ForCES Protocol . . . . 7
3.1.2. Responsibilities for HA . . . . . . . . . . . . . . . 9 3.1.2. Responsibilities for HA . . . . . . . . . . . . . . . 9
4. CE HA Hot Standby . . . . . . . . . . . . . . . . . . . . . . 10 4. CE HA Hot Standby . . . . . . . . . . . . . . . . . . . . . . 10
4.1. Changes to the FEPO model . . . . . . . . . . . . . . . . 10 4.1. Changes to the FEPO model . . . . . . . . . . . . . . . . 10
4.2. FEPO processing . . . . . . . . . . . . . . . . . . . . . 12 4.2. FEPO processing . . . . . . . . . . . . . . . . . . . . . 12
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
6. Security Considerations . . . . . . . . . . . . . . . . . . . 16 6. Security Considerations . . . . . . . . . . . . . . . . . . . 15
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
7.1. Normative References . . . . . . . . . . . . . . . . . . . 16 7.1. Normative References . . . . . . . . . . . . . . . . . . 16
7.2. Informative References . . . . . . . . . . . . . . . . . . 17 7.2. Informative References . . . . . . . . . . . . . . . . . 16
Appendix A. New FEPO version . . . . . . . . . . . . . . . . . . 17 Appendix A. New FEPO version . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 26 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25
1. Definitions 1. Definitions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119. document are to be interpreted as described in RFC 2119.
The following definitions are taken from [RFC3654]and [RFC3746]: The following definitions are taken from [RFC3654]and [RFC3746]:
o Logical Functional Block (LFB) -- A template that represents a o Logical Functional Block (LFB) -- A template that represents a
skipping to change at page 4, line 5 skipping to change at page 3, line 5
architecture that embodies the ForCES protocol and the state architecture that embodies the ForCES protocol and the state
transfer mechanisms as defined in [RFC5810]. transfer mechanisms as defined in [RFC5810].
o ForCES Protocol Transport Mapping Layer (ForCES TML) -- A layer in o ForCES Protocol Transport Mapping Layer (ForCES TML) -- A layer in
ForCES protocol architecture that specifically addresses the ForCES protocol architecture that specifically addresses the
protocol message transportation issues, such as how the protocol protocol message transportation issues, such as how the protocol
messages are mapped to different transport media (like SCTP, IP, messages are mapped to different transport media (like SCTP, IP,
TCP, UDP, ATM, Ethernet, etc), and how to achieve and implement TCP, UDP, ATM, Ethernet, etc), and how to achieve and implement
reliability, security, etc. reliability, security, etc.
o Forwarding Element (FE) - A logical entity that implements the
ForCES Protocol. FEs use the underlying hardware to provide per-
packet processing and handling as directed by a CE via the ForCES
Protocol.
o Control Element (CE) - A logical entity that implements the ForCES
Protocol and uses it to instruct one or more FEs on how to process
packets. CEs handle functionality such as the execution of
control and signaling protocols.
o ForCES Network Element (NE) - An entity composed of one or more
CEs and one or more FEs. An NE usually hides its internal
organization from external entities and represents a single point
of management to entities outside the NE.
o FE Manager (FEM) - A logical entity that operates in the pre-
association phase and is responsible for determining to which
CE(s) an FE should communicate. This process is called CE
discovery and may involve the FE manager learning the capabilities
of available CEs.
o CE Manager - A logical entity that operates in the pre-association
phase and is responsible for determining to which FE(s) a CE
should communicate. This process is called FE discovery and may
involve the CE manager learning the capabilities of available FEs.
2. Introduction 2. Introduction
Figure 1 illustrates a ForCES NE controlled by a set of redundant CEs Figure 1 illustrates a ForCES NE controlled by a set of redundant CEs
with CE1 being active and CE2 and CEN being a backup. with CE1 being active and CE2 and CEN being a backup.
----------------------------------------- -----------------------------------------
| ForCES Network Element | | ForCES Network Element |
| +-----------+ | | +-----------+ |
| | CEN | | | | CEN | |
| | (Backup) | | | | (Backup) | |
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enforces that only one CE be the master controller. This is known in enforces that only one CE be the master controller. This is known in
the industry as 1+N redundancy. The master CE controls the FEs via the industry as 1+N redundancy. The master CE controls the FEs via
the ForCES protocol operating in the Fp interface. If the master CE the ForCES protocol operating in the Fp interface. If the master CE
becomes faulty, a backup CE takes over and NE operation continues. becomes faulty, a backup CE takes over and NE operation continues.
By definition, the current documented setup is known as cold-standby. By definition, the current documented setup is known as cold-standby.
The set of CEs controlling an FE is static and is passed to the FE by The set of CEs controlling an FE is static and is passed to the FE by
the FE Manager (FEM) via the Ff interface and to each CE by the CE the FE Manager (FEM) via the Ff interface and to each CE by the CE
Manager (CEM) in the Fc interface during the pre-association phase. Manager (CEM) in the Fc interface during the pre-association phase.
From an FE perspective, the knobs of control for a CE set are defined From an FE perspective, the knobs of control for a CE set are defined
by the FEPO LFB in [RFC5810], Appendix B. Section 3.1 of this by the FEPO LFB in [RFC5810], Appendix B. In Section 3.1 of this
document details these knobs further. document we discuss further details of these knobs.
2.1. Document Scope 2.1. Document Scope
It is assumed that the reader is aware of the ForCES architecture to It is assumed that the reader is aware of the ForCES architecture to
make sense of the changes being described in this document. This make sense of the changes being described in this document. This
document provides background information to set the context of the document provides background information to set the context of the
discussion in Section 4. discussion in Section 4.
At the time this document is being written, the Fr interface is out At the time this document is being written, the Fr interface is out
of scope for the ForCES architecture. However, it is expected that of scope for the ForCES architecture. However, it is expected that
organizations implementing a set of CEs will need to have the CEs organizations implementing a set of CEs will need to have the CEs
communicate to each other via the Fr interface in order to achieve communicate to each other via the Fr interface in order to achieve
the synchronization necessary for controlling the FEs. the synchronization necessary for controlling the FEs.
The problem scope addressed by this document falls into 2 areas: The problem scope addressed by this document falls into 2 areas:
1. To describe with more clarity (than [RFC5810]) how current cold- 1. To describe with more clarity (than [RFC5810]) how current cold-
standby approach operates within the NE cluster. standby approach operates within the NE cluster.
2. To describe how to evolve the [RFC5810] cold-standby setup to a 2. To describe how to evolve the [RFC5810] cold-standby setup to a
hot-standby redundancy setup so as to improve the failover time hot-standby redundancy setup to improve the failover time and NE
and NE availability. availability.
2.2. Quantifying Problem Scope 2.2. Quantifying Problem Scope
The NE recovery and availability is dependent on several time- The NE recovery and availability is dependent on several time-
sensitive metrics: sensitive metrics:
1. How fast the CE plane failure is detected by the FE. 1. How fast the CE plane failure is detected by the FE.
2. How fast a backup CE becomes operational. 2. How fast a backup CE becomes operational.
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least one backup CE, then the system will be technically least one backup CE, then the system will be technically
operating in hot-standby mode. operating in hot-standby mode.
4. And last: How fast an FE recovers its state depends on how much 4. And last: How fast an FE recovers its state depends on how much
NE state exists. By ForCES current definition, the new master CE NE state exists. By ForCES current definition, the new master CE
assumes zero state on the FE and starts from scratch to update assumes zero state on the FE and starts from scratch to update
the FE. So the larger the state, the longer the recovery. the FE. So the larger the state, the longer the recovery.
3. RFC5810 CE HA Framework 3. RFC5810 CE HA Framework
To achieve CE High Availabilty, FEs and CEs MUST inter-operate per To achieve CE High Availability (HA), FEs and CEs MUST inter-operate
[RFC5810] definition which is repeated for contextual reasons in per [RFC5810] definition which is repeated for contextual reasons in
Section 3.1. It should be noted that in this default setup, which Section 3.1. It should be noted that in this default setup, which
MUST be implemented by CEs and FEs needing HA, the Fr plane is out of MUST be implemented by CEs and FEs requiring HA, the Fr plane is out
scope (and if available is proprietary to an implementation). of scope (and if available is proprietary to an implementation).
3.1. RFC 5810 CE High Availability Support 3.1. RFC 5810 CE HA Support
As mentioned earlier, although there can be multiple redundant CEs, As mentioned earlier, although there can be multiple redundant CEs,
only one CE actively controls FEs in a ForCES NE. In practice there only one CE actively controls FEs in a ForCES NE. In practice there
may be only one backup CE. At any moment in time, only one master CE may be only one backup CE. At any moment in time, only one master CE
can control an FE. In addition, the FE connects and associates to can control an FE. In addition, the FE connects and associates to
only the master CE. The FE and the CE are aware of the primary and only the master CE. The FE and the CE are aware of the primary and
one or more secondary CEs. This information (primary, secondary CEs) one or more secondary CEs. This information (primary, secondary CEs)
is configured on the FE and the CE during pre-association by the FEM is configured on the FE and the CE during pre-association by the FEM
and the CEM respectively. and the CEM respectively.
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| Event Report (pri CE down) | | Event Report (pri CE down) |
4 |------------------------------------------->| 4 |------------------------------------------->|
| | | |
| state update | | state update |
5 |<------------------------------------------>| 5 |<------------------------------------------>|
Figure 2: CE Failover for Cold Standby Figure 2: CE Failover for Cold Standby
3.1.1. Cold Standby Interaction with ForCES Protocol 3.1.1. Cold Standby Interaction with ForCES Protocol
High Availability parameterization in an FE is driven by configuring HA parameterization in an FE is driven by configuring the FE Protocol
the FE Protocol Object (FEPO) LFB. Object (FEPO) LFB.
The FEPO CEID component identifies the current master CE and the The FEPO CEID component identifies the current master CE and the
component table BackupCEs identifies the configured backup CEs. The component table BackupCEs identifies the configured backup CEs. The
FEPO FE Heartbeat Interval, CE Heartbeat Dead Interval, and CE FEPO FE Heartbeat Interval, CE Heartbeat Dead Interval, and CE
Heartbeat policy help in detecting connectivity problems between an Heartbeat policy help in detecting connectivity problems between an
FE and CE. The CE Failover policy defines how the FE should react on FE and CE. The CE Failover policy defines how the FE should react on
a detected failure. The FEObject FEState component [RFC5812] defines a detected failure. The FEObject FEState component [RFC5812] defines
the operational forwarding status and control. The CE can turn off the operational forwarding status and control. The CE can turn off
the FE's forwarding operations by setting the FEState to AdminDisable the FE's forwarding operations by setting the FEState to AdminDisable
and can turn it on by setting it to OperEnable. Note: [RFC5812] and can turn it on by setting it to OperEnable. Note: [RFC5812]
section 5.1 has an erratta which describes the FEState as read-only section 5.1 has an erratta which describes the FEState as read-only
when it should be read-write. when it should be read-write.
Figure 3 illustrates the defined state machine that facilitates Figure 3 illustrates the defined state machine that facilitates the
connection recovery. recovery of connection state.
The FE connects to the CE specified on FEPO CEID component. If it The FE connects to the CE specified on FEPO CEID component. If it
fails to connect to the defined CE, it moves it to the bottom of fails to connect to the defined CE, it moves it to the bottom of
table BackupCEs and sets its CEID component to be the first CE table BackupCEs and sets its CEID component to be the first CE
retrieved from table BackupCEs. The FE then attempts to associate retrieved from table BackupCEs. The FE then attempts to associate
with the CE designated as the new primary CE. The FE continues with the CE designated as the new primary CE. The FE continues
through this procedure until it successfully connects to one of the through this procedure until it successfully connects to one of the
CEs. CEs.
FE tries to associate FE tries to associate
+-->-----+ +-->-----+
| | | |
(CE changes master || | | (CE changes master || | |
CE issues Teardown || +---+--------v----+ CE issues Teardown || +---+--------v----+
Lost association) && | Pre-Association | Lost association) && | Pre-Association |
CE failover policy = 0 | (Association | CE failover policy = 0 | (Association |
+------------>-->-->| in +<----+ +------------>-->-->| in +<----+
| | progress) | | | | progress) | |
| | | | | | | |
| +--------+--------+ | | +--------+--------+ |
| CE Association | | CEFTI | CE Association | | CEFTI
| Response V | timer | Response V | timer
| +------------------+ | expires | +------------------+ | expires
| |FE issue CEPrimaryDown ^ | |FE issue CEPrimaryDown ^
| V | | V |
+-+-----------+ +------+-----+ +-+-----------+ +------+-----+
| | (CE changes master || | Not | | | (CE changes master || | Not |
| | CE issues Teardown || | Associated | | | CE issues Teardown || | Associated |
| | Lost association) && | +->---+ | | Lost association) && | +->---+
| Associated | CE Failover Policy = 1 |(May | FE | | Associated | CE Failover Policy = 1 |(May | FE |
| | | Continue |try v | | | Continue |try v
| |-------->------->------>| Forwarding)|assn | | |-------->------->------>| Forwarding)|assn |
| | Start CEFTI timer | |-<---+ | | Start CEFTI timer | |-<---+
| | | | | | | |
+-------------+ +-------+-----+ +-------------+ +-------+-----+
^ | ^ |
| Successful V | Successful V
| Association | | Association |
| Setup | | Setup |
| (Cancel CEFTI Timer) | | (Cancel CEFTI Timer) |
+_________________________________________+ +_________________________________________+
FE issue CEPrimaryDown event FE issue CEPrimaryDown event
Figure 3: FE State Machine considering HA Figure 3: FE State Machine considering HA
There are several events that trigger mastership changes: The master There are several events that trigger mastership changes: The master
CE may issue a mastership change (by changing the CEID value), or CE may issue a mastership change (by changing the CEID value), or
teardown an existing association; and last, connectivity may be lost teardown an existing association; and last, connectivity may be lost
between the CE and FE. between the CE and FE.
When communication fails between the FE and CE (which can be caused When communication fails between the FE and CE (which can be caused
by either the CE or link failure but not FE related), either the TML by either the CE or link failure but not FE related), either the TML
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PL Level: PL Level:
All other functionality, including configuring the HA behavior during All other functionality, including configuring the HA behavior during
setup, the CE IDs used to identify primary and secondary CEs, setup, the CE IDs used to identify primary and secondary CEs,
protocol messages used to report CE failure (Event Report), Heartbeat protocol messages used to report CE failure (Event Report), Heartbeat
messages used to detect association failure, messages to change the messages used to detect association failure, messages to change the
primary CE (Config), and other HA related operations described in primary CE (Config), and other HA related operations described in
Section 3.1, are the PL's responsibility. Section 3.1, are the PL's responsibility.
To put the two together, if a path to a primary CE is down, the TML To put the two together, if a path to a primary CE is down, the TML
would take care of failing over to a backup path, if one is would help recover from a failure by switching over to a backup path,
available. If the CE is totally unreachable then the PL would be if one is available. If the CE is totally unreachable then the PL
informed and it would take the appropriate actions described before. would be informed and it would take the appropriate actions described
before.
4. CE HA Hot Standby 4. CE HA Hot Standby
In this section we describe small extensions to the existing scheme In this section we describe small extensions to the existing scheme
to enable hot standby HA. To achieve hot standby HA, we target to to enable hot standby HA. To achieve hot standby HA, we target to
improve the specific goals defined in Section 2.2, namely: improve the specific goals defined in Section 2.2, namely:
o How fast a backup CE becomes operational. o How fast a backup CE becomes operational.
o How fast the FEs associate with the new master CE. o How fast the FEs associate with the new master CE.
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+ 2 (Associated) represents that the FE has successfully + 2 (Associated) represents that the FE has successfully
associated with the CE associated with the CE
+ 3 (IsMaster) represents that the FE has associated with + 3 (IsMaster) represents that the FE has associated with
the CE and is the master of the FE the CE and is the master of the FE
+ 4 (LostConnection) represents that the FE was associated + 4 (LostConnection) represents that the FE was associated
with the CE at one point but lost the connection with the CE at one point but lost the connection
+ 5 (Unreachable) represents the FE deems this CE + 5 (Unreachable) represents the FE deems this CE
unreachable. i.e the FE has tried over a period to connect unreachable. i.e the FE has tried over a period to
to it but has failed. connect to it but has failed.
2. HAModeValues an unsigned char to specify selected HA mode. 2. HAModeValues an unsigned char to specify selected HA mode.
Special values are: Special values are:
+ 0 (No HA Mode) The FE is not running in HA mode + 0 (No HA Mode) represents that the FE is not running in HA
mode
+ 1 (HA Mode - Cold Standby) The FE is in HA mode cold + 1 (HA Mode - Cold Standby) represents that the FE is in HA
Standby mode cold Standby
+ and 2 (HA Mode - Hot Standby) The FE is in HA mode hot + and 2 (HA Mode - Hot Standby) represents that the FE is in
Standby HA mode hot Standby
3. Statistics, a complex structure, representing the 3. Statistics, a complex structure, representing the
communication statistics between the FE and CE. The communication statistics between the FE and CE. The
components are: components are:
+ RecvPackets representing the packet count received from + RecvPackets representing the packet count received from
the CE the CE
+ RecvBytes representing the byte count received from the CE + RecvBytes representing the byte count received from the CE
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Array of the AllCEType. Array of the AllCEType.
2. Read-write HAMode of type HAModeValues to carry the HA mode 2. Read-write HAMode of type HAModeValues to carry the HA mode
used by the FE. used by the FE.
3. Added one additional Event, PrimaryCEChanged, reporting the new 3. Added one additional Event, PrimaryCEChanged, reporting the new
master CEID when there is a mastership change. master CEID when there is a mastership change.
Since no component from the FEPO v1 has been changed FEPO v1.1 Since no component from the FEPO v1 has been changed FEPO v1.1
retains backwards compatibility with CEs that know only version 1.0. retains backwards compatibility with CEs that know only version 1.0.
These CEs however cannot make use of the High Availability options These CEs however cannot make use of the HA options that the new FEPO
that the new FEPO provides. provides.
4.2. FEPO processing 4.2. FEPO processing
The FE's FEPO LFB version 1.1 AllCEs table contains all the CEIDs The FE's FEPO LFB version 1.1 AllCEs table contains all the CEIDs
that the FE may connect and associate with. The ordering of the CE that the FE may connect and associate with. The ordering of the CE
IDs in this table defines the priority order in which an FE will IDs in this table defines the priority order in which an FE will
connect to the CEs. This table is provisioned initially from the connect to the CEs. This table is provisioned initially from the
configuration plane (FEM). In the pre-association phase, the first configuration plane (FEM). In the pre-association phase, the first
CE (lowest table index) in the AllCEs table MUST be the first CE that CE (lowest table index) in the AllCEs table MUST be the first CE that
the FE will attempt to connect and associate with. If the FE fails the FE will attempt to connect and associate with. If the FE fails
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FE. Configuration messages (SET/DEL) from backup CEs MUST be dropped FE. Configuration messages (SET/DEL) from backup CEs MUST be dropped
by the FE and logged as received errors. by the FE and logged as received errors.
Asynchronous events that the master CE has subscribed to, as well as Asynchronous events that the master CE has subscribed to, as well as
heartbeats are sent to all associated-to CEs. Packet redirects heartbeats are sent to all associated-to CEs. Packet redirects
continue to be sent only to the master CE. The Heartbeat Interval, continue to be sent only to the master CE. The Heartbeat Interval,
the CEHB Policy and the FEHB Policy are global for all CEs(and the CEHB Policy and the FEHB Policy are global for all CEs(and
changed only by the master CE). changed only by the master CE).
Figure 4 illustrates the state machine that facilitates connection Figure 4 illustrates the state machine that facilitates connection
recovery with High Availability enabled. recovery with HA enabled.
FE tries to associate FE tries to associate
+-->-----+ +-->-----+
| | | |
(CE changes master || | | (CE changes master || | |
CE issues Teardown || +---+--------v----+ CE issues Teardown || +---+--------v----+
Lost association) && | Pre-Association | Lost association) && | Pre-Association |
CE failover policy = 0 | (Association | CE failover policy = 0 | (Association |
+------------>-->-->| in +<----+ +------------>-->-->| in +<----+
| | progress) | | | | progress) | |
| | | | | | | |
| +--------+--------+ | | +--------+--------+ |
| CE Association | | CEFTI | CE Association | | CEFTI
| Response V | timer | Response V | timer
| +------------------+ | expires | +------------------+ | expires
| |FE issue CEPrimaryDown ^ | |FE issue CEPrimaryDown ^
| |FE issue PrimaryCEChanged ^ | |FE issue PrimaryCEChanged ^
| V | | V |
+-+-----------+ +------+-----+ +-+-----------+ +------+-----+
| | (CE changes master || | Not | | | (CE changes master || | Not |
| | CE issues Teardown || | Associated | | | CE issues Teardown || | Associated |
| | Lost association) && | +->-----------+ | | Lost association) && | +->-----------+
| Associated | CE Failover Policy = 1 |(May |find first | | Associated | CE Failover Policy = 1 |(May |find first |
| | | Continue |associated v | | | Continue |associated v
| |-------->------->------>| Forwarding)|CE or retry | | |-------->------->------>| Forwarding)|CE or retry |
| | Start CEFTI timer | |associating | | | Start CEFTI timer | |associating |
| | | |-<-----------+ | | | |-<-----------+
| | | | | | | |
+----+--------+ +-------+----+ +----+--------+ +-------+----+
| | | |
^ Found | associated CE ^ Found | associated CE
| or newly | associated CE | or newly | associated CE
| V | V
| (Cancel CEFTI Timer) | | (Cancel CEFTI Timer) |
+_________________________________________+ +_________________________________________+
FE issue CEPrimaryDown event FE issue CEPrimaryDown event
FE issue PrimaryCEChanged event FE issue PrimaryCEChanged event
Figure 4: FE State Machine considering HA Figure 4: FE State Machine considering HA
Once the FE has associated with a master CE it moves to the post- Once the FE has associated with a master CE it moves to the post-
association phase (Associated state). It is assumed that the master association phase (Associated state). It is assumed that the master
CE will communicate with other CEs within the NE for the purpose of CE will communicate with other CEs within the NE for the purpose of
synchronization via the CE-CE interface. The CE-CE interface is out synchronization via the CE-CE interface. The CE-CE interface is out
of scope for this document. An election result amongst CEs may of scope for this document. An election result amongst CEs may
result in desire to change mastership to a different associated CE; result in desire to change mastership to a different associated CE;
at which point current assumed master CE will instruct the FE to use at which point current assumed master CE will instruct the FE to use
a different master CE. a different master CE.
FE CE#1 CE#2 ... CE#N FE CE#1 CE#2 ... CE#N
| | | | | | | |
| Asso Estb,Caps exchg | | | | Asso Estb,Caps exchg | | |
1 |<-------------------->| | | 1 |<-------------------->| | |
| | | | | | | |
| state update | | | | state update | | |
2 |<-------------------->| | | 2 |<-------------------->| | |
| | | | | | | |
| Asso Estb,Caps exchg | | | Asso Estb,Caps exchg | |
3I|<--------------------------------->| | 3I|<--------------------------------->| |
... ... ... ... ... ... ... ...
| Asso Estb,Caps exchg | | Asso Estb,Caps exchg |
3N|<------------------------------------------>| 3N|<------------------------------------------>|
| | | | | | | |
4 |<-------------------->| | | 4 |<-------------------->| | |
. . . . . . . .
4x|<-------------------->| | | 4x|<-------------------->| | |
| FAILURE | | | FAILURE | |
| | | | | | | |
| Event Report (LastCEID changed) | | | Event Report (LastCEID changed) | |
5 |---------------------------------->|------->| 5 |---------------------------------->|------->|
| Event Report (CE#2 is new master) | | | Event Report (CE#2 is new master) | |
6 |---------------------------------->|------->| 6 |---------------------------------->|------->|
| | | | | |
7 |<--------------------------------->| | 7 |<--------------------------------->| |
. . . . . . . .
7x|<--------------------------------->| | 7x|<--------------------------------->| |
. . . . . . . .
Figure 5: CE Failover for Hot Standby Figure 5: CE Failover for Hot Standby
While in the post-association phase, if the CE Failover Policy is set While in the post-association phase, if the CE Failover Policy is set
to 1 and HAMode set to 2 (HotStandby) then the FE, after succesfully to 1 and HAMode set to 2 (HotStandby) then the FE, after succesfully
associating with the master CE, MUST attempt to connect and associate associating with the master CE, MUST attempt to connect and associate
with all the CEs that it is aware of. Figure 5 steps #1 and #2 with all the CEs that it is aware of. Figure 5 steps #1 and #2
illustrates the FE associating with CE#1 as the master and then illustrates the FE associating with CE#1 as the master and then
proceeding to steps #3I to #3N the association with backup CEs CE#2 proceeding to steps #3I to #3N the association with backup CEs CE#2
to CE#N. If the FE fails to connect or associate with some CEs, the to CE#N. If the FE fails to connect or associate with some CEs, the
FE MAY flag them as unreachable to avoid continuous attempts to FE MAY flag them as unreachable to avoid continuous attempts to
connect. The FE MAY retry to reassociate with unreachable CEs when connect. The FE MAY retry to reassociate with unreachable CEs when
possible. possible.
When the master CE for any reason is considered to be down, then the When the master CE for any reason is considered to be down, then the
FE MUST try to find the first associated CE from the list of all CEs FE MUST try to find the first associated CE from the list of all CEs
in a round-robin fashion. in a round-robin fashion.
If the FE is unable to find an associated FE in its list of CEs, then If the FE is unable to find an associated FE in its list of CEs, then
it MUST attempt to connect and associate with the first from the list it MUST attempt to connect and associate with the first from the list
of all CEs and continue in a round-robin fashion until it connects of all CEs and continue in a round-robin fashion until it connects
and associates with a CE. and associates with a CE.
Once the FE selects an associated CE to use as the new master, the FE Once the FE selects an associated CE to use as the new master, the FE
issues a PrimaryCEDown Event Notification to all associated CEs to issues a PrimaryCEDown Event Notification to all associated CEs to
notify them that the last primary CE went down (and what its identity notify them that the last primary CE went down (and what its identity
was); a second event PrimaryCEChanged identifying the new master CE was); a second event PrimaryCEChanged identifying the new master CE
is sent as well to identify which CE the reporting FE considers to be is sent as well to identify which CE the reporting FE considers to be
the new master. the new master.
In most High Availability architectures there exists the possibility In most HA architectures there exists the possibility of split-brain.
of split-brain. However, since in our setup the FE will never accept However, since in our setup the FE will never accept any
any configuration messages from any other than the master CE, we configuration messages from any other than the master CE, we consider
consider the FE as fenced against data corruption from the other CEs the FE as fenced against data corruption from the other CEs that
that consider themselves as the master. The split-brain issue consider themselves as the master. The split-brain issue becomes
becomes mostly a CE-CE communication problem which is considered to mostly a CE-CE communication problem which is considered to be out of
be out of scope. scope.
By virtue of having multiple CE connections, the FE switchover to a By virtue of having multiple CE connections, the FE switchover to a
new master CE will be relatively much faster. The overall effect is new master CE will be relatively much faster. The overall effect is
improving the NE recovery time in case of communication failure or improving the NE recovery time in case of communication failure or
faults of the master CE. This satisfies the requirement we set to faults of the master CE. This satisfies the requirement we set to
achieve. achieve.
5. IANA Considerations 5. IANA Considerations
XXX: This document updates an IANA registered FE Protocol object XXX: This document updates an IANA registered FE Protocol object
skipping to change at page 16, line 43 skipping to change at page 16, line 9
section on FEPO. section on FEPO.
6. Security Considerations 6. Security Considerations
Security consideration as defined in section 9 of [RFC5810] applies. Security consideration as defined in section 9 of [RFC5810] applies.
7. References 7. References
7.1. Normative References 7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5810] Doria, A., Hadi Salim, J., Haas, R., Khosravi, H., Wang, [RFC5810] Doria, A., Hadi Salim, J., Haas, R., Khosravi, H., Wang,
W., Dong, L., Gopal, R., and J. Halpern, "Forwarding and W., Dong, L., Gopal, R., and J. Halpern, "Forwarding and
Control Element Separation (ForCES) Protocol Control Element Separation (ForCES) Protocol
Specification", RFC 5810, March 2010. Specification", RFC 5810, March 2010.
7.2. Informative References 7.2. Informative References
[RFC3654] Khosravi, H. and T. Anderson, "Requirements for Separation [RFC3654] Khosravi, H. and T. Anderson, "Requirements for Separation
of IP Control and Forwarding", RFC 3654, November 2003. of IP Control and Forwarding", RFC 3654, November 2003.
[RFC3746] Yang, L., Dantu, R., Anderson, T., and R. Gopal, [RFC3746] Yang, L., Dantu, R., Anderson, T., and R. Gopal,
"Forwarding and Control Element Separation (ForCES) "Forwarding and Control Element Separation (ForCES)
Framework", RFC 3746, April 2004. Framework", RFC 3746, April 2004.
[RFC5812] Halpern, J. and J. Hadi Salim, "Forwarding and Control [RFC5812] Halpern, J. and J. Hadi Salim, "Forwarding and Control
Element Separation (ForCES) Forwarding Element Model", Element Separation (ForCES) Forwarding Element Model", RFC
RFC 5812, March 2010. 5812, March 2010.
Appendix A. New FEPO version Appendix A. New FEPO version
The xml has been validated against the schema defined in [RFC5812].
<LFBLibrary xmlns="urn:ietf:params:xml:ns:forces:lfbmodel:1.0" <LFBLibrary xmlns="urn:ietf:params:xml:ns:forces:lfbmodel:1.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="lfb-schema.xsd" provides="FEPO"> xsi:noNamespaceSchemaLocation="lfb-schema.xsd" provides="FEPO">
<!-- XXX --> <!-- XXX -->
<dataTypeDefs> <dataTypeDefs>
<dataTypeDef> <dataTypeDef>
<name>CEHBPolicyValues</name> <name>CEHBPolicyValues</name>
<synopsis> <synopsis>
The possible values of CE heartbeat policy The possible values of CE heartbeat policy
</synopsis> </synopsis>
<atomic> <atomic>
<baseType>uchar</baseType> <baseType>uchar</baseType>
<specialValues> <specialValues>
<specialValue value="0"> <specialValue value="0">
<name>CEHBPolicy0</name> <name>CEHBPolicy0</name>
<synopsis> <synopsis>
The CE will send heartbeats to the FE The CE will send heartbeats to the FE
every CEHDI timeout if no other messages every CEHDI timeout if no other messages
have been sent since. have been sent since.
</synopsis> </synopsis>
</specialValue> </specialValue>
<specialValue value="1"> <specialValue value="1">
<name>CEHBPolicy1</name> <name>CEHBPolicy1</name>
<synopsis> <synopsis>
The CE will not send heartbeats to the FE The CE will not send heartbeats to the FE
</synopsis> </synopsis>
</specialValue> </specialValue>
</specialValues> </specialValues>
</atomic> </atomic>
</dataTypeDef> </dataTypeDef>
<dataTypeDef> <dataTypeDef>
<name>FEHBPolicyValues</name> <name>FEHBPolicyValues</name>
<synopsis> <synopsis>
The possible values of FE heartbeat policy The possible values of FE heartbeat policy
</synopsis> </synopsis>
skipping to change at page 19, line 36 skipping to change at page 18, line 50
<synopsis> <synopsis>
The possible values of CE failover policy The possible values of CE failover policy
</synopsis> </synopsis>
<atomic> <atomic>
<baseType>uchar</baseType> <baseType>uchar</baseType>
<specialValues> <specialValues>
<specialValue value="0"> <specialValue value="0">
<name>CEFailoverPolicy0</name> <name>CEFailoverPolicy0</name>
<synopsis> <synopsis>
The FE should stop functioning immediate and The FE should stop functioning immediate and
transition to the FE OperDisable state transition to the FE OperDisable state
</synopsis> </synopsis>
</specialValue> </specialValue>
<specialValue value="1"> <specialValue value="1">
<name>CEFailoverPolicy1</name> <name>CEFailoverPolicy1</name>
<synopsis> <synopsis>
The FE should continue forwarding even without an The FE should continue forwarding even without an
associated CE for CEFTI. The FE goes to FE associated CE for CEFTI. The FE goes to FE
OperDisable when the CEFTI expires and no OperDisable when the CEFTI expires and no
association. Requires graceful restart support. association. Requires graceful restart support.
</synopsis> </synopsis>
</specialValue> </specialValue>
</specialValues> </specialValues>
</atomic> </atomic>
</dataTypeDef> </dataTypeDef>
<dataTypeDef> <dataTypeDef>
<name>FEHACapab</name> <name>FEHACapab</name>
<synopsis> <synopsis>
The supported HA features The supported HA features
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