draft-ietf-ccamp-gmpls-recovery-terminology-02.txt   draft-ietf-ccamp-gmpls-recovery-terminology-03.txt 
CCAMP Working Group CCAMP GMPLS P&R Design Team CCAMP Working Group CCAMP GMPLS P&R Design Team
Internet Draft Internet Draft
Category: Standard Track Eric Mannie (Editor) Category: Standard Track Eric Mannie (Editor)
Expiration Date: November 2003 Dimitri Papadimitriou (Editor) Expiration Date: June 2004 Dimitri Papadimitriou (Editor)
May 2003 January 2004
Recovery (Protection and Restoration) Terminology Recovery (Protection and Restoration) Terminology for GMPLS
for Generalized Multi-Protocol Label Switching (GMPLS)
draft-ietf-ccamp-gmpls-recovery-terminology-02.txt draft-ietf-ccamp-gmpls-recovery-terminology-03.txt
Status of this Memo Status of this Memo
This document is an Internet-Draft and is subject to all provisions This document is an Internet-Draft and is subject to all provisions
of Section 10 of RFC2026. of Section 10 of RFC2026.
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 other Task Force (IETF), its areas, and its working groups. Note that other
groups may also distribute working documents as Internet-Drafts. groups may also distribute working documents as Internet-Drafts.
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(GMPLS) based recovery mechanisms (i.e. protection and restoration) (GMPLS) based recovery mechanisms (i.e. protection and restoration)
that are under consideration by the CCAMP Working Group. that are under consideration by the CCAMP Working Group.
The terminology proposed in this document is intended to be The terminology proposed in this document is intended to be
independent of the underlying transport technologies and borrows independent of the underlying transport technologies and borrows
from an ITU-T ongoing effort, the Draft Recommendation [G.808.1] from an ITU-T ongoing effort, the Draft Recommendation [G.808.1]
(ex. G.GPS - Generic Protection Switching) and from the G.841 ITU-T (ex. G.GPS - Generic Protection Switching) and from the G.841 ITU-T
Recommendation. The restoration terminology and concepts have been Recommendation. The restoration terminology and concepts have been
gathered from numerous sources including IETF drafts. gathered from numerous sources including IETF drafts.
E.Mannie, D.Papadimitriou et al.- Internet Draft - November 2003 2 E.Mannie, D.Papadimitriou et al.- Internet Draft - June 2004 2
In the context of this document we will use the term "recovery" to In the context of this document we will use the term "recovery" to
denote both protection and restoration. The specific terms denote both protection and restoration. The specific terms
"protection" and "restoration" will only be used when "protection" and "restoration" will only be used when
differentiation is required. differentiation is required.
Note that this document focuses on the terminology for the recovery Note that this document focuses on the terminology for the recovery
of LSPs controlled by a GMPLS control plane. We focus on end-to-end, of LSPs controlled by a GMPLS control plane. We focus on end-to-end,
segment and span (i.e. link) LSP recovery. Terminology for control segment and span (i.e. link) LSP recovery. Terminology for control
plane recovery is not in the scope of this document. plane recovery is not in the scope of this document.
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This section defines the following general terms common to both This section defines the following general terms common to both
protection and restoration (i.e. recovery). In addition, most of protection and restoration (i.e. recovery). In addition, most of
these terms apply to end-to-end, segment and span LSP recovery. Note these terms apply to end-to-end, segment and span LSP recovery. Note
that span recovery does not protect the nodes at each end of the that span recovery does not protect the nodes at each end of the
span, otherwise end-to-end or segment LSP recovery should be used. span, otherwise end-to-end or segment LSP recovery should be used.
The terminology and the definitions have been originally taken from The terminology and the definitions have been originally taken from
G.808.1. However, for generalization, the following language that is G.808.1. However, for generalization, the following language that is
E.Mannie, D.Papadimitriou et al.- Internet Draft - November 2003 3 E.Mannie, D.Papadimitriou et al.- Internet Draft - June 2004 3
not directly related to recovery has been adapted to GMPLS and the not directly related to recovery has been adapted to GMPLS and the
common IETF terminology: common IETF terminology:
An LSP is used as a generic term to designate either an SNC (Sub- An LSP is used as a generic term to designate either an SNC (Sub-
Network Connection) or an NC (Network Connection) in ITU-T Network Connection) or an NC (Network Connection) in ITU-T
terminology. The ITU-T uses the term transport entity to designate terminology. The ITU-T uses the term transport entity to designate
either a link, an SNC or an NC. The term "Traffic" is used instead either a link, an SNC or an NC. The term "Traffic" is used instead
of "Traffic Signal". The term protection or restoration "scheme" is of "Traffic Signal". The term protection or restoration "scheme" is
used instead of protection or restoration "architecture". used instead of protection or restoration "architecture".
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restored. restored.
C. Null traffic: C. Null traffic:
Traffic carried over the recovery LSP/span if it is not used to Traffic carried over the recovery LSP/span if it is not used to
carry normal or extra traffic. Null traffic can be any kind of carry normal or extra traffic. Null traffic can be any kind of
traffic that conforms to the signal structure of the specific layer, traffic that conforms to the signal structure of the specific layer,
and it is ignored (not selected) at the egress of the recovery and it is ignored (not selected) at the egress of the recovery
LSP/span. LSP/span.
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4.3 LSP/Span Protection and Restoration 4.3 LSP/Span Protection and Restoration
E.Mannie, D.Papadimitriou et al.- Internet Draft - November 2003 4
The following subtle distinction is generally made between the terms The following subtle distinction is generally made between the terms
"protection" and "restoration", even though these terms are often "protection" and "restoration", even though these terms are often
used interchangeably [TEWG]. used interchangeably [TEWG].
The distinction between protection and restoration is made based on The distinction between protection and restoration is made based on
the resource allocation done during the recovery LSP/span the resource allocation done during the recovery LSP/span
establishment. The distinction between different types of establishment. The distinction between different types of
restoration is made based on the level of route computation, restoration is made based on the level of route computation,
signaling and resource allocation done during the restoration signaling and resource allocation done during the restoration
LSP/span establishment. LSP/span establishment.
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establishment of the restoration LSP/span occurs only after a establishment of the restoration LSP/span occurs only after a
failure of the working LSP/span, and requires some additional failure of the working LSP/span, and requires some additional
signaling. signaling.
Both protection and restoration require signaling. Signaling to Both protection and restoration require signaling. Signaling to
establish the recovery resources and signaling associated with the establish the recovery resources and signaling associated with the
use of the recovery LSP(s)/span(s) are needed. use of the recovery LSP(s)/span(s) are needed.
4.4 Recovery Scope 4.4 Recovery Scope
Recovery can be applied at various levels throughout the network. Recovery can be applied at various levels throughout the network. An
LSP may be subject to local (span), segment, and/or end-to-end
recovery.
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Local (span) recovery refers to the recovery of an LSP over a link Local (span) recovery refers to the recovery of an LSP over a link
between two nodes. Segment recovery refers to the recovery of an LSP between two nodes.
segment (i.e. an SNC in the ITU-T terminology) between two nodes,
i.e. the boundary nodes of the segment. End-to-end recovery refers
E.Mannie, D.Papadimitriou et al.- Internet Draft - November 2003 5 End-to-end recovery refers to the recovery of an entire LSP from its
to the recovery of an entire LSP from its source to its destination. source (ingress node end-point) to its destination (egress node end-
An LSP may be subject to local (span), segment, and/or end-to-end point).
recovery.
Segment recovery refers to the recovery over a portion of the
network of a segment LSP (i.e. an SNC in the ITU-T terminology) of
an end-to-end LSP. Such recovery protects against span and/or node
failure over a particular portion of the network traversed by an
end-to-end LSP.
4.5 Recovery Domain 4.5 Recovery Domain
A recovery domain is defined as a set of nodes and spans over which A recovery domain is defined as a set of nodes and spans over which
one or more recovery schemes are provided. A recovery domain served one or more recovery schemes are provided. A recovery domain served
by one single recovery scheme is referred to as a "single recovery by one single recovery scheme is referred to as a "single recovery
domain", while a recovery domain served by multiple recovery schemes domain", while a recovery domain served by multiple recovery schemes
is referred to as a "multi recovery domain". is referred to as a "multi recovery domain".
The recovery operation is contained within the recovery domain. A The recovery operation is contained within the recovery domain. A
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restoration. restoration.
B. 0:1 type: unprotected B. 0:1 type: unprotected
No specific recovery LSP/span protects the working LSP/span. No specific recovery LSP/span protects the working LSP/span.
However, the working LSP/span can potentially be restored through However, the working LSP/span can potentially be restored through
any alternate available route/span, with or without any pre-computed any alternate available route/span, with or without any pre-computed
restoration route. Note that there are no resources pre-established restoration route. Note that there are no resources pre-established
for this recovery type. for this recovery type.
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This type is applicable to LSP/span restoration, but not to LSP/span This type is applicable to LSP/span restoration, but not to LSP/span
protection. Span restoration can be for instance achieved by moving protection. Span restoration can be for instance achieved by moving
all the LSPs transported over of a failed span to a dynamically all the LSPs transported over of a failed span to a dynamically
selected span. selected span.
C. 1:1 type: dedicated recovery with extra traffic C. 1:1 type: dedicated recovery with extra traffic
One specific recovery LSP/span protects exactly one specific working One specific recovery LSP/span protects exactly one specific working
LSP/span but the normal traffic is transmitted only over one LSP LSP/span but the normal traffic is transmitted only over one LSP
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(working or recovery) at a time. Extra traffic can be transported (working or recovery) at a time. Extra traffic can be transported
using the recovery LSP/span resources. using the recovery LSP/span resources.
This type is applicable to LSP/span protection and LSP restoration, This type is applicable to LSP/span protection and LSP restoration,
but not to span restoration. but not to span restoration.
D. 1:N (N > 1) type: shared recovery with extra traffic D. 1:N (N > 1) type: shared recovery with extra traffic
A specific recovery LSP/span is dedicated to the protection of up to A specific recovery LSP/span is dedicated to the protection of up to
N working LSPs/spans. The set of working LSPs/spans is explicitly N working LSPs/spans. The set of working LSPs/spans is explicitly
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A set of M specific recovery LSPs/spans protects a set of up to N A set of M specific recovery LSPs/spans protects a set of up to N
specific working LSPs/spans. The two sets are explicitly identified. specific working LSPs/spans. The two sets are explicitly identified.
Extra traffic can be transported over the M recovery LSPs/spans when Extra traffic can be transported over the M recovery LSPs/spans when
available. All the LSPs/spans must start and end at the same nodes. available. All the LSPs/spans must start and end at the same nodes.
Sometimes, the working LSPs/spans are assumed to be resource Sometimes, the working LSPs/spans are assumed to be resource
disjoint in the network so that they do not share any failure disjoint in the network so that they do not share any failure
probability, but this is not mandatory. Obviously, if several probability, but this is not mandatory. Obviously, if several
working LSPs/spans in the set of N are concurrently affected by some working LSPs/spans in the set of N are concurrently affected by some
failure(s), the traffic on only M of these failed LSPs/spans may be failure(s), the traffic on only M of these failed LSPs/spans may be
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recovered. Note that N can be arbitrarily large (i.e. infinite). The recovered. Note that N can be arbitrarily large (i.e. infinite). The
choice of N and M is a policy decision. choice of N and M is a policy decision.
This type is applicable to LSP/span protection and LSP restoration, This type is applicable to LSP/span protection and LSP restoration,
but not to span restoration. but not to span restoration.
4.7 Bridge Types 4.7 Bridge Types
A bridge is the function that connects the normal traffic and extra A bridge is the function that connects the normal traffic and extra
traffic to the working and recovery LSP/span. traffic to the working and recovery LSP/span.
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A. Permanent bridge A. Permanent bridge
Under a 1+1 type, the bridge connects the normal traffic to both the Under a 1+1 type, the bridge connects the normal traffic to both the
working and protection LSPs/spans. This type of bridge is not working and protection LSPs/spans. This type of bridge is not
applicable to restoration types. There is of course no extra traffic applicable to restoration types. There is of course no extra traffic
connected to the recovery LSP/span. connected to the recovery LSP/span.
B. Broadcast bridge B. Broadcast bridge
For 1:N and M:N types, the bridge permanently connects the normal For 1:N and M:N types, the bridge permanently connects the normal
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Is a selector that extracts the normal traffic from either the Is a selector that extracts the normal traffic from either the
working LSP/span output or the recovery LSP/span output. working LSP/span output or the recovery LSP/span output.
B. Merging selector B. Merging selector
For 1:N and M:N protection types, the selector permanently extracts For 1:N and M:N protection types, the selector permanently extracts
the normal traffic from both the working and recovery LSP/span the normal traffic from both the working and recovery LSP/span
outputs. This alternative works only in combination with a selector outputs. This alternative works only in combination with a selector
bridge. bridge.
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4.9 Recovery GMPLS Nodes 4.9 Recovery GMPLS Nodes
This section defines the GMPLS nodes involved during recovery. This section defines the GMPLS nodes involved during recovery.
A. Ingress GMPLS node of an end-to-end LSP/segment LSP/span A. Ingress GMPLS node of an end-to-end LSP/segment LSP/span
The ingress node of an end-to-end LSP/segment LSP/span is where the The ingress node of an end-to-end LSP/segment LSP/span is where the
normal traffic may be bridged to the recovery end-to-end LSP/segment normal traffic may be bridged to the recovery end-to-end LSP/segment
LSP/span. Also known as source node in the ITU-T terminology. LSP/span. Also known as source node in the ITU-T terminology.
B. Egress GMPLS node of an end-to-end LSP/segment LSP/span B. Egress GMPLS node of an end-to-end LSP/segment LSP/span
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The egress node of an end-to-end LSP/segment LSP/span is where the The egress node of an end-to-end LSP/segment LSP/span is where the
normal traffic may be selected from either the working or the normal traffic may be selected from either the working or the
recovery end-to-end LSP/segment LSP/span. Also known as sink node in recovery end-to-end LSP/segment LSP/span. Also known as sink node in
the ITU-T terminology. the ITU-T terminology.
C. Intermediate GMPLS node of an end-to-end LSP/segment LSP C. Intermediate GMPLS node of an end-to-end LSP/segment LSP
A node along either the working or recovery end-to-end LSP/segment A node along either the working or recovery end-to-end LSP/segment
LSP route between the corresponding ingress and egress nodes. Also LSP route between the corresponding ingress and egress nodes. Also
known as intermediate node in the ITU-T terminology. known as intermediate node in the ITU-T terminology.
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A revertive recovery operation refers to a recovery switching A revertive recovery operation refers to a recovery switching
operation, where the traffic returns to (or remains on) the working operation, where the traffic returns to (or remains on) the working
LSP/span if the switch requests are terminated; i.e. when the LSP/span if the switch requests are terminated; i.e. when the
working LSP/span has recovered from the failure. working LSP/span has recovered from the failure.
Therefore a non-revertive recovery switching operation is when the Therefore a non-revertive recovery switching operation is when the
traffic does not return to the working LSP/span if the switch traffic does not return to the working LSP/span if the switch
requests are terminated. requests are terminated.
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4.12 Failure Reporting 4.12 Failure Reporting
This section gives (for information) several signal types commonly This section gives (for information) several signal types commonly
used in transport planes to report a failure condition. Note that used in transport planes to report a failure condition. Note that
fault reporting may require additional signaling mechanisms. fault reporting may require additional signaling mechanisms.
A. Signal Degrade (SD): a signal indicating that the associated data A. Signal Degrade (SD): a signal indicating that the associated data
has degraded. has degraded.
B. Signal Fail (SF): a signal indicating that the associated data B. Signal Fail (SF): a signal indicating that the associated data
has failed. has failed.
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C. Signal Degrade Group (SDG): a signal indicating that the C. Signal Degrade Group (SDG): a signal indicating that the
associated group data has degraded. associated group data has degraded.
D. Signal Fail Group (SFG): a signal indicating that the associated D. Signal Fail Group (SFG): a signal indicating that the associated
group has failed. group has failed.
Note: SDG and SFG definitions are under discussion at the ITU-T. Note: SDG and SFG definitions are under discussion at the ITU-T.
4.13 External commands 4.13 External commands
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action to be taken, and as such freezes the current state. action to be taken, and as such freezes the current state.
D. Forced switch for normal traffic: D. Forced switch for normal traffic:
A switch action initiated externally that switches normal traffic to A switch action initiated externally that switches normal traffic to
the recovery LSP/span, unless an equal or higher priority switch the recovery LSP/span, unless an equal or higher priority switch
command is in effect. command is in effect.
E. Manual switch for normal traffic: E. Manual switch for normal traffic:
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A switch action initiated externally that switches normal traffic to A switch action initiated externally that switches normal traffic to
the recovery LSP/span, unless a fault condition exists on other the recovery LSP/span, unless a fault condition exists on other
LSPs/spans (including the recovery LSP/span) or an equal or higher LSPs/spans (including the recovery LSP/span) or an equal or higher
priority switch command is in effect. priority switch command is in effect.
F. Manual switch for recovery LSP/span: F. Manual switch for recovery LSP/span:
A switch action initiated externally that switches normal traffic to A switch action initiated externally that switches normal traffic to
the working LSP/span, unless a fault condition exists on the working the working LSP/span, unless a fault condition exists on the working
LSP/span or an equal or higher priority switch command is in effect. LSP/span or an equal or higher priority switch command is in effect.
G. Clear: G. Clear:
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An action initiated externally that clears the active external An action initiated externally that clears the active external
command. command.
4.14 Unidirectional versus Bi-Directional Recovery Switching 4.14 Unidirectional versus Bi-Directional Recovery Switching
A. Unidirectional recovery switching: A. Unidirectional recovery switching:
A recovery switching mode in which, for a unidirectional fault (i.e. A recovery switching mode in which, for a unidirectional fault (i.e.
a fault affecting only one direction of transmission), only the a fault affecting only one direction of transmission), only the
normal traffic transported in the affected direction (of the LSP or normal traffic transported in the affected direction (of the LSP or
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A. Full Span Recovery A. Full Span Recovery
All the S LSP carried over a given span are recovered under span All the S LSP carried over a given span are recovered under span
failure condition. Full span recovery is also referred to as "bulk failure condition. Full span recovery is also referred to as "bulk
recovery". recovery".
B. Partial Span Recovery B. Partial Span Recovery
Only a subset s of the S LSP carried over a given span are recovered Only a subset s of the S LSP carried over a given span are recovered
under span failure condition. Both selection criteria of the under span failure condition. Both selection criteria of the
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entities belonging to this subset and the decision concerning the entities belonging to this subset and the decision concerning the
recovery of the remaining (S - s) LSP are based on local policy. recovery of the remaining (S - s) LSP are based on local policy.
4.16 Recovery Schemes Related Time and Durations 4.16 Recovery Schemes Related Time and Durations
This section gives several typical timing definitions that are of This section gives several typical timing definitions that are of
importance for recovery schemes. importance for recovery schemes.
A. Detection time: A. Detection time:
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The time between the occurrence of the fault or degradation and its The time between the occurrence of the fault or degradation and its
detection. Note that this is a rather theoretical time since in detection. Note that this is a rather theoretical time since in
practice this is difficult to measure. practice this is difficult to measure.
B. Correlation time: B. Correlation time:
The time between detection of the fault or degradation and the The time between detection of the fault or degradation and the
reporting of the signal fail or degrade. This time is typically used reporting of the signal fail or degrade. This time is typically used
in correlating related failures or degradations. in correlating related failures or degradations.
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4.17 Impairment 4.17 Impairment
A defect or performance degradation, which may lead to SF or SD A defect or performance degradation, which may lead to SF or SD
trigger. trigger.
4.18 Recovery Ratio 4.18 Recovery Ratio
The quotient of the actually recovery bandwidth divided by the The quotient of the actually recovery bandwidth divided by the
traffic bandwidth which is intended to be protected. traffic bandwidth which is intended to be protected.
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4.19 Hitless Protection Switch 4.19 Hitless Protection Switch
Protection switch, which does not cause data loss, data duplication, Protection switch, which does not cause data loss, data duplication,
data disorder, or bit errors upon recovery switching action. data disorder, or bit errors upon recovery switching action.
4.20 Network Survivability 4.20 Network Survivability
The set of capabilities that allow a network to restore affected The set of capabilities that allow a network to restore affected
traffic in the event of a failure. The degree of survivability is traffic in the event of a failure. The degree of survivability is
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determined by the network∆s capability to survive single and determined by the network∆s capability to survive single and
multiple failures. multiple failures.
4.21 Survivable Network 4.21 Survivable Network
A network that is capable of restoring traffic in the event of a A network that is capable of restoring traffic in the event of a
failure. failure.
4.22 Escalation 4.22 Escalation
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about the location (and so the identity) of the transport plane about the location (and so the identity) of the transport plane
entity that causes the LSP(s)/span(s) failure. The deciding entity entity that causes the LSP(s)/span(s) failure. The deciding entity
can then take accurate decision to achieve finer grained recovery can then take accurate decision to achieve finer grained recovery
switching action(s). switching action(s).
- Phase 3: Failure Notification - Phase 3: Failure Notification
Failure notification phase is used 1) to inform intermediate nodes Failure notification phase is used 1) to inform intermediate nodes
that LSP(s)/span(s) failure has occurred and has been detected 2) to that LSP(s)/span(s) failure has occurred and has been detected 2) to
inform the recovery deciding entities (which can correspond to any inform the recovery deciding entities (which can correspond to any
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intermediate or end-point of the failed LSP/span) that the intermediate or end-point of the failed LSP/span) that the
corresponding LSP/span is not available. corresponding LSP/span is not available.
- Phase 4: Recovery (Protection or Restoration) - Phase 4: Recovery (Protection or Restoration)
See above. See above.
- Phase 5: Reversion (Normalization) - Phase 5: Reversion (Normalization)
See above. See above.
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The combination of Failure Detection and Failure Localization and The combination of Failure Detection and Failure Localization and
Notification is referred to as Fault Management. Notification is referred to as Fault Management.
5.1 Entities Involved During Recovery 5.1 Entities Involved During Recovery
The entities involved during the recovery operations can be defined The entities involved during the recovery operations can be defined
as follows; these entities are parts of ingress, egress and as follows; these entities are parts of ingress, egress and
intermediate nodes as defined previously: intermediate nodes as defined previously:
A. Detecting Entity (Failure Detection): A. Detecting Entity (Failure Detection):
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The process of moving failed LSPs from a failed (working) span to a The process of moving failed LSPs from a failed (working) span to a
protection span must be initiated by one of the nodes terminating protection span must be initiated by one of the nodes terminating
the span, e.g. A or B. The deciding (and recovering) entity is the span, e.g. A or B. The deciding (and recovering) entity is
referred to as the "master" while the other node is called the referred to as the "master" while the other node is called the
"slave" and corresponds to a recovering only entity. "slave" and corresponds to a recovering only entity.
Note: The determination of the master and the slave may be based on Note: The determination of the master and the slave may be based on
configured information or protocol specific requirements. configured information or protocol specific requirements.
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6. Protection Schemes 6. Protection Schemes
This section clarifies the multiple possible protection schemes and This section clarifies the multiple possible protection schemes and
the specific terminology for the protection. the specific terminology for the protection.
6.1 1+1 protection 6.1 1+1 protection
1+1 protection has one working LSP/span, one protection LSP/span and 1+1 protection has one working LSP/span, one protection LSP/span and
a permanent bridge. At the ingress node, the normal traffic is a permanent bridge. At the ingress node, the normal traffic is
permanently bridged to both the working and protection LSP/span. At permanently bridged to both the working and protection LSP/span. At
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the egress node, the normal traffic is selected from the better of the egress node, the normal traffic is selected from the better of
the two LSPs/spans. the two LSPs/spans.
Due to the permanent bridging, the 1+1 protection does not allow an Due to the permanent bridging, the 1+1 protection does not allow an
unprotected extra traffic signal to be provided. unprotected extra traffic signal to be provided.
6.2 1:N (N >= 1) Protection 6.2 1:N (N >= 1) Protection
1:N protection has N working LSPs/spans carrying normal traffic and 1:N protection has N working LSPs/spans carrying normal traffic and
1 protecting LSP/span that may carry extra-traffic. 1 protecting LSP/span that may carry extra-traffic.
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its working LSP/span and may be connected to the protection LSP/span its working LSP/span and may be connected to the protection LSP/span
(case of broadcast bridge), or is connected to either its working or (case of broadcast bridge), or is connected to either its working or
the protection LSP/span (case of selector bridge). At the egress the protection LSP/span (case of selector bridge). At the egress
node, the normal traffic is selected from either its working or node, the normal traffic is selected from either its working or
protection LSP/span. protection LSP/span.
Unprotected extra traffic can be transported over the protection Unprotected extra traffic can be transported over the protection
LSP/span whenever the protection LSP/span is not used to carry a LSP/span whenever the protection LSP/span is not used to carry a
normal traffic. normal traffic.
6.3 M:N (N >= M) Protection 6.3 M:N (M, N > 1, M =< N) Protection
M:N protection has N working LSPs/spans carrying normal traffic and M:N protection has N working LSPs/spans carrying normal traffic and
M protecting LSP/span that may carry extra-traffic. M protecting LSP/span that may carry extra-traffic.
At the ingress, a normal traffic is either permanently connected to At the ingress, a normal traffic is either permanently connected to
its working LSP/span and may be connected to one of the protection its working LSP/span and may be connected to one of the protection
LSPs/spans (case of broadcast bridge), or is connected to either its LSPs/spans (case of broadcast bridge), or is connected to either its
working or one of the protection LSPs/spans (case of selector working or one of the protection LSPs/spans (case of selector
bridge). At the egress node, the normal traffic is selected from bridge). At the egress node, the normal traffic is selected from
either its working or one of the protection LSP/span. either its working or one of the protection LSP/span.
Unprotected extra traffic can be transported over the M protection Unprotected extra traffic can be transported over the M protection
LSP/span whenever the protection LSPs/spans is not used to carry a LSP/span whenever the protection LSPs/spans is not used to carry a
normal traffic. normal traffic.
Note1: all protection types are either uni- or bi-directional, Note1: all protection types are either uni- or bi-directional,
obviously, the latter applies only to bi-directional LSP/span and obviously, the latter applies only to bi-directional LSP/span and
requires coordination between the ingress and egress node during requires coordination between the ingress and egress node during
protection switching. protection switching.
E.Mannie, D.Papadimitriou et al.- Internet Draft - June 2004 15
Note2: all protection types except 1+1 unidirectional protection Note2: all protection types except 1+1 unidirectional protection
switching require a communication channel between the ingress and switching require a communication channel between the ingress and
the egress node. the egress node.
Note3: in the GMPLS context, span protection refers to the full or Note3: in the GMPLS context, span protection refers to the full or
partial span recovery of the LSPs carried over that span (see partial span recovery of the LSPs carried over that span (see
Section 4.15). Section 4.15).
7. Restoration Schemes 7. Restoration Schemes
E.Mannie, D.Papadimitriou et al.- Internet Draft - November 2003 15
This section clarifies the multiple possible restoration schemes and This section clarifies the multiple possible restoration schemes and
the specific terminology for the restoration. the specific terminology for the restoration.
7.1 Pre-planned LSP Restoration 7.1 Pre-planned LSP Restoration
Also referred to as pre-planned LSP re-routing. Before failure Also referred to as pre-planned LSP re-routing. Before failure
detection and/or notification, one or more restoration LSPs are detection and/or notification, one or more restoration LSPs are
instantiated between the same ingress-egress node pair than the instantiated between the same ingress-egress node pair than the
working LSP. Note that the restoration resources must be pre- working LSP. Note that the restoration resources must be pre-
computed, must be signaled and may be selected a priori, but not computed, must be signaled and may be selected a priori, but not
cross-connected and thus are able to carry extra-traffic. cross-connected. Thus, the restoration LSP is not able to carry any
extra-traffic.
The complete establishment of the restoration LSP (i.e. activation) The complete establishment of the restoration LSP (i.e. activation)
occurs only after failure detection and/or notification of the occurs only after failure detection and/or notification of the
working LSP and requires some additional restoration signaling. working LSP and requires some additional restoration signaling.
Therefore, this mechanism protects against working LSP failure(s) Therefore, this mechanism protects against working LSP failure(s)
but requires activation of the restoration LSP after failure but requires activation of the restoration LSP after failure
occurrence. After the ingress node has activated the restoration occurrence. After the ingress node has activated the restoration
LSP, the latter can carry the normal traffic. LSP, the latter can carry the normal traffic.
Note: when each working LSP is recoverable by exactly one Note: when each working LSP is recoverable by exactly one
restoration LSP, one refers also to 1:1 re-routing without extra- restoration LSP, one refers also to 1:1 (pre-planned) re-routing
traffic. without extra-traffic.
7.1.1 Shared-Mesh Restoration 7.1.1 Shared-Mesh Restoration
"Shared-mesh" restoration is defined as a particular case of pre- "Shared-mesh" restoration is defined as a particular case of pre-
planned LSP re-routing that reduces the restoration resource planned LSP re-routing that reduces the restoration resource
requirements by allowing multiple restoration LSPs (initiated from requirements by allowing multiple restoration LSPs (initiated from
distinct ingress nodes) to share common resources (including links distinct ingress nodes) to share common resources (including links
and nodes.) and nodes.)
7.2 LSP Restoration 7.2 LSP Restoration
Also referred to as LSP re-routing. The ingress node switches the Also referred to as LSP re-routing. The ingress node switches the
normal traffic to an alternate LSP signaled and fully established normal traffic to an alternate LSP signaled and fully established
(i.e. cross-connected) after failure detection and/or notification. (i.e. cross-connected) after failure detection and/or notification.
The alternate LSP path may be pre-computed after failure detection The alternate LSP path may be computed after failure detection
and/or notification. In this case, one refers to "Full LSP Re- and/or notification. In this case, one also refers to "Full LSP Re-
routing." routing."
E.Mannie, D.Papadimitriou et al.- Internet Draft - June 2004 16
The alternate LSP is signaled from the ingress node and may reuse The alternate LSP is signaled from the ingress node and may reuse
intermediate node's resources of the working LSP under failure intermediate node's resources of the working LSP under failure
condition (and may also include additional intermediate nodes.) condition (and may also include additional intermediate nodes.)
7.2.1 Hard LSP Restoration 7.2.1 Hard LSP Restoration
Also referred to as hard LSP re-routing. A re-routing operation Also referred to as hard LSP re-routing. A re-routing operation
where the LSP is released before the full establishment of an where the LSP is released before the full establishment of an
alternate LSP (i.e. break-before-make). alternate LSP (i.e. break-before-make).
E.Mannie, D.Papadimitriou et al.- Internet Draft - November 2003 16
7.2.2 Soft LSP Restoration 7.2.2 Soft LSP Restoration
Also referred to as soft LSP re-routing. A re-routing operation Also referred to as soft LSP re-routing. A re-routing operation
where the LSP is released after the full establishment of an where the LSP is released after the full establishment of an
alternate LSP (i.e. make-before-break). alternate LSP (i.e. make-before-break).
8. Security Considerations 8. Security Considerations
This document does not introduce or imply any specific security This document does not introduce or imply any specific security
consideration. consideration.
skipping to change at line 884 skipping to change at line 894
The IETF invites any interested party to bring to its attention any The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary copyrights, patents or patent applications, or other proprietary
rights, which may cover technology that may be required to practice rights, which may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive this standard. Please address the information to the IETF Executive
Director. Director.
10. References 10. References
10.1 Normative References 10.1 Normative References
E.Mannie, D.Papadimitriou et al.- Internet Draft - June 2004 17
[G.707] ITU-T, "Network Node Interface for the Synchronous [G.707] ITU-T, "Network Node Interface for the Synchronous
Digital Hierarchy (SDH)," Recommendation G.707, October Digital Hierarchy (SDH)," Recommendation G.707, October
2000. 2000.
[G.841] ITU-T, "Types and Characteristics of SDH Network [G.841] ITU-T, "Types and Characteristics of SDH Network
Protection Architectures," Recommendation G.841, Protection Architectures," Recommendation G.841,
October 1998. October 1998.
[G.842] ITU-T, "Interworking of SDH network protection [G.842] ITU-T, "Interworking of SDH network protection
architectures," Recommendation G.842, October 1998. architectures," Recommendation G.842, October 1998.
E.Mannie, D.Papadimitriou et al.- Internet Draft - November 2003 17
[GMPLS-ARCH] E.Mannie (Editor), "Generalized MPLS Architecture,"
Internet Draft, Work in progress, draft-ietf-ccamp-
gmpls-architecture-06.txt, April 2003.
[RFC-2026] S.Bradner, "The Internet Standards Process -- Revision [RFC-2026] S.Bradner, "The Internet Standards Process -- Revision
3", BCP 9, RFC 2026, October 1996. 3", BCP 9, RFC 2026, October 1996.
[RFC-2119] S.Bradner, "Key words for use in RFCs to Indicate [RFC-2119] S.Bradner, "Key words for use in RFCs to Indicate
Requirement Levels," BCP 14, RFC 2119, March 1997. Requirement Levels," BCP 14, RFC 2119, March 1997.
[T1.105] ANSI, "Synchronous Optical Network (SONET): Basic [T1.105] ANSI, "Synchronous Optical Network (SONET): Basic
Description Including Multiplex Structure, Rates, and Description Including Multiplex Structure, Rates, and
Formats," ANSI T1.105, January 2001. Formats," ANSI T1.105, January 2001.
skipping to change at line 929 skipping to change at line 935
Recommendation G.783, October 2000. Recommendation G.783, October 2000.
[G.806] ITU-T, "Characteristics of Transport Equipment Ż [G.806] ITU-T, "Characteristics of Transport Equipment Ż
Description Methodology and Generic Functionality," Description Methodology and Generic Functionality,"
Recommendation G.806, October 2000. Recommendation G.806, October 2000.
[G.808.1] ITU-T, "Generic Protection Switching Ż Linear trail and [G.808.1] ITU-T, "Generic Protection Switching Ż Linear trail and
subnetwork protection," Draft Recommendation (work in subnetwork protection," Draft Recommendation (work in
progress), Version 0.5, January 2003. progress), Version 0.5, January 2003.
[GMPLS-ARCH] E.Mannie (Editor), "Generalized MPLS Architecture,"
Internet Draft, Work in progress, draft-ietf-ccamp-
gmpls-architecture-06.txt, April 2003.
[SUDHEER] S.Dharanikota et al., "NNI Protection and restoration [SUDHEER] S.Dharanikota et al., "NNI Protection and restoration
requirements," OIF Contribution 507, 2001. requirements," OIF Contribution 507, 2001.
[TEWG] W.S.Lai, et al., "Network Hierarchy and Multilayer [TEWG] W.S.Lai, et al., "Network Hierarchy and Multilayer
Survivability," Internet Draft, Work in progress, Survivability," Internet Draft, Work in progress,
draft-ietf-tewg-restore-hierarchy-01.txt, June 2002. draft-ietf-tewg-restore-hierarchy-01.txt, June 2002.
E.Mannie, D.Papadimitriou et al.- Internet Draft - June 2004 18
11. Acknowledgments 11. Acknowledgments
Valuable comments and input were received from many people. Valuable comments and input were received from many people.
12. Author's Addresses 12. Author's Addresses
Eric Mannie (Consult) Eric Mannie (Consult)
Email: eric_mannie@hotmail.com Email: eric_mannie@hotmail.com
Dimitri Papadimitriou (Alcatel) Dimitri Papadimitriou (Alcatel)
Francis Wellesplein, 1 Francis Wellesplein, 1
B-2018 Antwerpen, Belgium B-2018 Antwerpen, Belgium
E.Mannie, D.Papadimitriou et al.- Internet Draft - November 2003 18
Phone: +32 3 240-8491 Phone: +32 3 240-8491
Email: dimitri.papadimitriou@alcatel.be Email: dimitri.papadimitriou@alcatel.be
E.Mannie, D.Papadimitriou et al.- Internet Draft - November 2003 19 E.Mannie, D.Papadimitriou et al.- Internet Draft - June 2004 19
Full Copyright Statement Full Copyright Statement
"Copyright (C) The Internet Society (date). All Rights Reserved. "Copyright (C) The Internet Society (date). All Rights Reserved.
This document and translations of it may be copied and furnished to This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph kind, provided that the above copyright notice and this paragraph
are included on all such copies and derivative works. However, this are included on all such copies and derivative works. However, this
skipping to change at line 982 skipping to change at line 992
The limited permissions granted above are perpetual and will not be The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns. revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE." MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE."
E.Mannie, D.Papadimitriou et al.- Internet Draft - November 2003 20 E.Mannie, D.Papadimitriou et al.- Internet Draft - June 2004 20
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