draft-ietf-ccamp-gmpls-ason-routing-eval-02.txt   draft-ietf-ccamp-gmpls-ason-routing-eval-03.txt 
CCAMP Working Group Chris Hopps (Cisco) CCAMP Working Group Chris Hopps (Cisco)
Internet Draft Lyndon Ong (Ciena) Internet Draft Lyndon Ong (Ciena)
Category: Informational Dimitri Papadimitriou (Alcatel) Category: Informational Dimitri Papadimitriou (Alcatel)
Jonathan Sadler (Tellabs) Jonathan Sadler (Tellabs)
Expiration Date: April 2006 Stephen Shew (Nortel) Expiration Date: December 2006 Stephen Shew (Nortel)
Dave Ward (Cisco) Dave Ward (Cisco)
October 2005 May 2006
Evaluation of existing Routing Protocols Evaluation of existing Routing Protocols
against ASON routing requirements against ASON routing requirements
draft-ietf-ccamp-gmpls-ason-routing-eval-02.txt draft-ietf-ccamp-gmpls-ason-routing-eval-03.txt
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Copyright Notice
Copyright (C) The Internet Society (2005). All Rights Reserved.
Abstract Abstract
The Generalized MPLS (GMPLS) suite of protocols has been defined to The Generalized MPLS (GMPLS) suite of protocols has been defined to
control different switching technologies as well as different control different switching technologies as well as different
applications. These include support for requesting TDM connections applications. These include support for requesting TDM connections
including SONET/SDH and Optical Transport Networks (OTNs). including SONET/SDH and Optical Transport Networks (OTNs).
This document provides an evaluation of the IETF Routing Protocols This document provides an evaluation of the IETF Routing Protocols
against the routing requirements for an Automatically Switched against the routing requirements for an Automatically Switched
Optical Network (ASON) as defined by ITU-T. Optical Network (ASON) as defined by ITU-T.
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1. Contributors 1. Contributors
This document is the result of the CCAMP Working Group ASON Routing This document is the result of the CCAMP Working Group ASON Routing
Solution design team joint effort. Solution design team joint effort.
Dimitri Papadimitriou (Alcatel, Team Leader and Editor) Dimitri Papadimitriou (Alcatel, Team Leader and Editor)
EMail: dimitri.papadimitriou@alcatel.be EMail: dimitri.papadimitriou@alcatel.be
Chris Hopps (Cisco) Chris Hopps (Cisco)
EMail: chopps@rawdofmt.org EMail: chopps@rawdofmt.org
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Dave Ward (Cisco) Dave Ward (Cisco)
EMail: dward@cisco.com EMail: dward@cisco.com
2. Conventions used in this document 2. Conventions used in this document
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 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
The reader is expected to be familiar with the terminology introduced The reader is expected to be familiar with the terminology introduced
in [ASON-RR]. in [RFC4258].
3. Introduction 3. Introduction
There are certain capabilities that are needed to support the ITU-T There are certain capabilities that are needed to support the ITU-T
Automatically Switched Optical Network (ASON) control plane Automatically Switched Optical Network (ASON) control plane
architecture as defined in [G.8080]. architecture as defined in [G.8080].
[ASON-RR] details the routing requirements for the GMPLS routing [RFC4258] details the routing requirements for the GMPLS routing
suite of protocols to support the capabilities and functionality of suite of protocols to support the capabilities and functionality of
ASON control planes identified in [G.7715] and in [G.7715.1]. The ASON control planes identified in [G.7715] and in [G.7715.1]. The
ASON routing architecture provides for a conceptual reference ASON routing architecture provides for a conceptual reference
architecture, with definition of functional components and common architecture, with definition of functional components and common
information elements to enable end-to-end routing in the case of information elements to enable end-to-end routing in the case of
protocol heterogeneity and facilitate management of ASON networks. protocol heterogeneity and facilitate management of ASON networks.
This description is only conceptual: no physical partitioning of This description is only conceptual: no physical partitioning of
these functions is implied. these functions is implied.
However, [ASON-RR] does not address GMPLS routing protocol However, [RFC4258] does not address GMPLS routing protocol
applicability or capabilities. This document evaluates the IETF applicability or capabilities. This document evaluates the IETF
Routing Protocols against the requirements identified in [ASON-RR]. Routing Protocols against the requirements identified in [RFC4258].
The result of this evaluation is detailed in Section 5. Close The result of this evaluation is detailed in Section 5. Close
examination of applicability scenarios and the result of the examination of applicability scenarios and the result of the
evaluation of these scenarios are provided in Section 6. evaluation of these scenarios are provided in Section 6.
ASON (Routing) terminology sections are provided in Appendix 1 and 2. ASON (Routing) terminology sections are provided in Appendix 1 and 2.
4. Requirements - Overview
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4. Requirements - Overview
The following functionality is expected from GMPLS routing protocols The following functionality is expected from GMPLS routing protocols
to instantiate the ASON hierarchical routing architecture realization to instantiate the ASON hierarchical routing architecture realization
(see [G.7715] and [G.7715.1]): (see [G.7715] and [G.7715.1]):
- Routing Areas (RAs) shall be uniquely identifiable within a - Routing Areas (RAs) shall be uniquely identifiable within a
carrier's network, each having a unique RA Identifier (RA ID) carrier's network, each having a unique RA Identifier (RA ID)
within the carrier's network. within the carrier's network.
- Within a RA (one level), the routing protocol shall support - Within a RA (one level), the routing protocol shall support
dissemination of hierarchical routing information (including dissemination of hierarchical routing information (including
summarized routing information for other levels) in support of an summarized routing information for other levels) in support of an
architecture of multiple hierarchical levels of RAs; the number of architecture of multiple hierarchical levels of RAs; the number of
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Reachability information may be advertised either as a set of UNI Reachability information may be advertised either as a set of UNI
Transport Resource address prefixes, or a set of associated Transport Resource address prefixes, or a set of associated
Subnetwork Point Pool (SNPP) link IDs/SNPP link ID prefixes, assigned Subnetwork Point Pool (SNPP) link IDs/SNPP link ID prefixes, assigned
and selected consistently in their applicability scope. The formats and selected consistently in their applicability scope. The formats
of the control plane identifiers in a protocol realization are of the control plane identifiers in a protocol realization are
implementation specific. Use of a routing protocol within a RA should implementation specific. Use of a routing protocol within a RA should
not restrict the choice of routing protocols for use in other RAs not restrict the choice of routing protocols for use in other RAs
(child or parent). (child or parent).
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As ASON does not restrict the control plane architecture choice, As ASON does not restrict the control plane architecture choice,
either a co-located architecture or a physically separated either a co-located architecture or a physically separated
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architecture may be used. A collection of links and nodes such as a architecture may be used. A collection of links and nodes such as a
sub-network or RA must be able to represent itself to the wider sub-network or RA must be able to represent itself to the wider
network as a single logical entity with only its external links network as a single logical entity with only its external links
visible to the topology database. visible to the topology database.
5. Evaluation 5. Evaluation
This section evaluates support of existing IETF routing protocols This section evaluates support of existing IETF routing protocols
with respect to the requirements summarized from [ASON-RR] in Section with respect to the requirements summarized from [RFC4258] in Section
4. Candidate routing protocols are IGP (OSPF and IS-IS) and BGP. The 4. Candidate routing protocols are IGP (OSPF and IS-IS) and BGP. The
latter in not addressed in the current version of this document. BGP latter is not addressed in the current version of this document. BGP
is not considered a candidate protocol mainly because of is not considered a candidate protocol mainly because of
- non-support of TE information exchange: each BGP router advertises - non-support of TE information exchange: each BGP router advertises
only its path to each destination in its vector for loop avoidance, only its path to each destination in its vector for loop avoidance,
with no costs or hop counts; each BGP router knows little about with no costs or hop counts; each BGP router knows little about
network topology network topology
- BGP can only advertise routes that are eligible for use (local RIB) - BGP can only advertise routes that are eligible for use (local RIB)
or routing loops can occur; there is one best route per prefix, and or routing loops can occur; there is one best route per prefix, and
that is the route that is advertised. that is the route that is advertised.
- BGP is not widely deployed in optical equipment and networks - BGP is not widely deployed in optical equipment and networks
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- Pi is a physical (bearer/data/transport plane) node - Pi is a physical (bearer/data/transport plane) node
- Li is a logical control plane entity that is associated to a - Li is a logical control plane entity that is associated to a
single data plane (abstract) node. The Li is identified by the single data plane (abstract) node. The Li is identified by the
TE Router_ID. The latter is a control plane identifier defined as TE Router_ID. The latter is a control plane identifier defined as
follows: follows:
. [RFC 3630]: Router_Address (top level) TLV of the Type 1 TE LSA . [RFC 3630]: Router_Address (top level) TLV of the Type 1 TE LSA
. [RFC 3784]: Traffic Engineering Router ID TLV (Type 134) . [RFC 3784]: Traffic Engineering Router ID TLV (Type 134)
Note: this document does not define what the TE Router ID is. This Note: this document does not define what the TE Router ID is. This
document simply states that the use of the TE Router ID to document simply states the use of the TE Router ID to
identify Li. [RFC 3630] and [RFC3784] provide the definitions. identify Li. [RFC 3630] and [RFC3784] provide the definitions.
- Ri is a logical control plane entity that is associated to a - Ri is a logical control plane entity that is associated to a
control plane "router". The latter is the source for topology control plane "router". The latter is the source for topology
information that it generates and shares with other control plane information that it generates and shares with other control plane
"routers". The Ri is identified by the (advertising) Router_ID "routers". The Ri is identified by the (advertising) Router_ID
. [RFC 2328]: Router ID (32-bit) . [RFC 2328]: Router ID (32-bit)
. [RFC 1195]: IS-IS System ID (48-bit) . [RFC 1195]: IS-IS System ID (48-bit)
The Router_ID, represented by Ri and that corresponds to the RC_ID The Router_ID, represented by Ri and that corresponds to the RC_ID
[ASON-RR], does not enter into the identification of the logical [RFC4258], does not enter into the identification of the logical
entities representing the data plane resources such as links. The entities representing the data plane resources such as links. The
Routing DataBase (RDB) is associated to the Ri. Note that, in the Routing DataBase (RDB) is associated to the Ri. Note that, in the
ASON context, arrangement considering multiple Ri's announcing ASON context, an arrangement consisting of multiple Ri's
routing information related to a single Li is under evaluation. announcing routing information related to a single Li is under
evaluation.
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Aside from the Li/Pi mappings, these identifiers are not assumed to Aside from the Li/Pi mappings, these identifiers are not assumed to
be in a particular entity relationship except that the Ri may have be in a particular entity relationship except that the Ri may have
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multiple Li in its scope. The relationship between Ri and Li is multiple Li in its scope. The relationship between Ri and Li is
simple at any moment in time: an Li may be advertised by only one Ri simple at any moment in time: an Li may be advertised by only one Ri
at any time. However, an Ri may advertise a set of one or more Li's. at any time. However, an Ri may advertise a set of one or more Li's.
Thus, the routing protocol MUST be able to advertise multiple TE Thus, the routing protocol MUST be able to advertise multiple TE
Router IDs (see Section 5.7). Router IDs (see Section 5.7).
Note: Si is a control plane signaling function associated with one Note: Si is a control plane signaling function associated with one
or more Li. This document does not assume any specific constraint on or more Li. This document does not assume any specific constraint on
the relationship between Si and Li. This document does not discuss the relationship between Si and Li. This document does not discuss
issues of control plane accessibility for signaling function, and issues of control plane accessibility for the signaling function,
makes no assumptions about how control plane accessibility to the Si and makes no assumptions about how control plane accessibility to
is achieved. the Si is achieved.
5.2 RA Identification 5.2 RA Identification
G.7715.1 notes some necessary characteristics for RA identifiers, G.7715.1 notes some necessary characteristics for RA identifiers,
e.g., that they may provide scope for the Ri, and that they must be e.g., that they may provide scope for the Ri, and that they must be
provisioned to be unique within an administrative domain. The RA ID provisioned to be unique within an administrative domain. The RA ID
format itself is allowed to be derived from any global address space. format itself is allowed to be derived from any global address space.
Provisioning of RA IDs for uniqueness is outside the scope of this Provisioning of RA IDs for uniqueness is outside the scope of this
document. document.
Under these conditions, GMPLS link state routing protocols provide Under these conditions, GMPLS link state routing protocols provide
the capability for RA Identification without further modification. the capability for RA Identification without further modification.
5.3 Routing Information Exchange 5.3 Routing Information Exchange
We focus on routing information exchange between Ri entities In this section, the focus is on routing information exchange Ri
(through routing adjacencies) within a single hierarchical level. entities (through routing adjacencies) within a single hierarchical
Routing information mapping between levels require specific level. Routing information mapping between levels require specific
processing (see Section 5.5). processing (see Section 5.5).
The control plane does not transport Pi identifiers as these are The control plane does not transport Pi identifiers as these are
data plane addresses for which the Li/Pi mapping is kept (link) data plane addresses for which the Li/Pi mapping is kept (link)
local - see for instance the transport LMP document [LMP-T] where local - see for instance the transport LMP document [RFC4394] where
such exchange is described. Example: the transport plane identifier such an exchange is described. Example: the transport plane
is the Pi (the identifier assigned to the physical element) that identifier is the Pi (the identifier assigned to the physical
could be for instance "666B.F999.AF10.222C", whereas the control element) that could be for instance "666B.F999.AF10.222C", whereas
plane identifier is the Li (the identifier assigned by the control the control plane identifier is the Li (the identifier assigned by
plane), which could be for instance "192.0.2.1". the control plane), which could be for instance "192.0.2.1".
The control plane exchanges the control plane identifier information The control plane exchanges the control plane identifier information
but not the transport plane identifier information (i.e. not but not the transport plane identifier information (i.e. not
"666B.F999.AF10.222C" but only "192.0.2.1"). The mapping Li/Pi is "666B.F999.AF10.222C" but only "192.0.2.1"). The mapping Li/Pi is
kept local. So, when the Si receives a control plane message kept local. So, when the Si receives a control plane message
requesting the use of "192.0.2.1", Si knows locally that this requesting the use of "192.0.2.1", Si knows locally that this
information refers to the data plane entity identified by the information refers to the data plane entity identified by the
transport plane identifier "666B.F999.AF10.222C". transport plane identifier "666B.F999.AF10.222C".
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Note also that the Li and Pi addressing spaces may be identical. Note also that the Li and Pi addressing spaces may be identical.
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The control plane carries: The control plane carries:
1) its view of the data plane link end-points and other link 1) its view of the data plane link end-points and other link
connection end-points connection end-points
2) the identifiers scoped by the Li's i.e. referred to as an 2) the identifiers scoped by the Li's i.e. referred to as an
associated IPv4/IPv6 addressing space; note that these identifiers associated IPv4/IPv6 addressing space; note that these identifiers
may either be bundled TE link addresses or component link addresses may either be bundled TE link addresses or component link addresses
3) when using OSPF or ISIS as the IGP in support of traffic 3) when using OSPF or ISIS as the IGP in support of traffic
engineering, [RFC 3477] RECOMMENDS that the Li value (referred to engineering, [RFC 3477] RECOMMENDS that the Li value (referred to
the "LSR Router ID") to be set to the TE Router ID value. the "LSR Router ID") to be set to the TE Router ID value.
OSPF and IS-IS therefore carry sufficient node identification Therefore, OSPF and IS-IS carry sufficient node identification
information without further modification. information without further modification.
5.3.1 Link Attributes 5.3.1 Link Attributes
[ASON-RR] provides a list of link attributes and characteristics [RFC4258] provides a list of link attributes and characteristics
that need to be advertised by a routing protocol. All TE link that need to be advertised by a routing protocol. All TE link
attributes and characteristics are currently handled by OSPF and IS- attributes and characteristics are currently handled by OSPF and IS-
IS (see Table 1) with the exception of Local Adaptation support. IS (see Table 1) with the exception of Local Adaptation support.
Indeed, GMPLS routing does not currently consider the use of Indeed, GMPLS routing does not currently consider the use of
dedicated TE link attribute(s) to describe the cross/inter-layer dedicated TE link attribute(s) to describe the cross/inter-layer
relationships. relationships.
In addition, the representation of bandwidth requires further In addition, the representation of bandwidth requires further
consideration. Indeed, GMPLS Routing defines an Interface Switching consideration. GMPLS Routing defines an Interface Switching
Capability Descriptor (ISCD) that delivers information about the Capability Descriptor (ISCD) that delivers information about the
(maximum/ minimum) bandwidth per priority of which an LSP can make (maximum/ minimum) bandwidth per priority of which an LSP can make
use. This information is usually used in combination with the use. This information is usually used in combination with the
Unreserved Bandwidth sub-TLV that provides the amount of bandwidth Unreserved Bandwidth sub-TLV that provides the amount of bandwidth
not yet reserved on a TE link. not yet reserved on a TE link.
In the ASON context, other bandwidth accounting representations are In the ASON context, other bandwidth accounting representations are
possible, e.g., in terms of a set of tuples <signal_type; number of possible, e.g., in terms of a set of tuples <signal_type; number of
unallocated timeslots>. The latter representation may also require unallocated timeslots>. The latter representation may also require
definition of additional signal types (from those defined in definition of additional signal types (from those defined in
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However, the method proposed in [RFC4202] is the most However, the method proposed in [RFC4202] is the most
straightforward without requiring any bandwidth accounting change straightforward without requiring any bandwidth accounting change
from an LSR perspective (in particular, when the ISCD sub-TLV from an LSR perspective (in particular, when the ISCD sub-TLV
information is combined with the information provided by the information is combined with the information provided by the
Unreserved Bandwidth sub-TLV). Unreserved Bandwidth sub-TLV).
Link Characteristics GMPLS OSPF Link Characteristics GMPLS OSPF
----------------------- ---------- ----------------------- ----------
Local SNPP link ID Link local part of the TE link identifier Local SNPP link ID Link local part of the TE link identifier
sub-TLV [RFC4203] sub-TLV [RFC4203]
Remote SNPP link ID Link remote part of the TE link identifier
sub-TLV [RFC4203]
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Remote SNPP link ID Link remote part of the TE link identifier
sub-TLV [RFC4203]
Signal Type Technology specific part of the Interface Signal Type Technology specific part of the Interface
Switching Capability Descriptor sub-TLV Switching Capability Descriptor sub-TLV
[RFC4203] [RFC4203]
Link Weight TE metric sub-TLV [RFC3630] Link Weight TE metric sub-TLV [RFC3630]
Resource Class Administrative Group sub-TLV [RFC3630] Resource Class Administrative Group sub-TLV [RFC3630]
Local Connection Types Switching Capability field part of the Local Connection Types Switching Capability field part of the
Interface Switching Capability Descriptor Interface Switching Capability Descriptor
sub-TLV [RFC4203] sub-TLV [RFC4203]
Link Capacity Unreserved bandwidth sub-TLV [RFC3630] Link Capacity Unreserved bandwidth sub-TLV [RFC3630]
Max LSP Bandwidth part of the Interface Max LSP Bandwidth part of the Interface
Switching Capability Descriptor sub-TLV Switching Capability Descriptor sub-TLV
[RFC4203] [RFC4203]
Link Availability Link Protection sub-TLV [RFC4203] Link Availability Link Protection sub-TLV [RFC4203]
Diversity Support SRLG sub-TLV [RFC4203] Diversity Support SRLG sub-TLV [RFC4203]
Local Adaptation support see above Local Adaptation support see above
Table 1. TE link Attributes in GMPLS OSPF-TE
Link Characteristics GMPLS IS-IS Link Characteristics GMPLS IS-IS
----------------------- ----------- ----------------------- -----------
Local SNPP link ID Link local part of the TE link identifier Local SNPP link ID Link local part of the TE link identifier
sub-TLV [RFC4205] sub-TLV [RFC4205]
Remote SNPP link ID Link remote part of the TE link identifier Remote SNPP link ID Link remote part of the TE link identifier
sub-TLV [RFC4205] sub-TLV [RFC4205]
Signal Type Technology specific part of the Interface Signal Type Technology specific part of the Interface
Switching Capability Descriptor sub-TLV Switching Capability Descriptor sub-TLV
[RFC4205] [RFC4205]
Link Weight TE Default metric [RFC3784] Link Weight TE Default metric [RFC3784]
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Interface Switching Capability Descriptor Interface Switching Capability Descriptor
sub-TLV [RFC4205] sub-TLV [RFC4205]
Link Capacity Unreserved bandwidth sub-TLV [RFC3784] Link Capacity Unreserved bandwidth sub-TLV [RFC3784]
Max LSP Bandwidth part of the Interface Max LSP Bandwidth part of the Interface
Switching Capability Descriptor sub-TLV Switching Capability Descriptor sub-TLV
[GMPLS-ISIS] [GMPLS-ISIS]
Link Availability Link Protection sub-TLV [RFC4205] Link Availability Link Protection sub-TLV [RFC4205]
Diversity Support SRLG sub-TLV [RFC4205] Diversity Support SRLG sub-TLV [RFC4205]
Local Adaptation support see above Local Adaptation support see above
Table 1. TE link Attribute in GMPLS OSPF-TE and GMPLS IS-IS-TE, Table 2. TE link Attributes in GMPLS IS-IS-TE
respectively
Note: Link Attributes represent layer resource capabilities and Note: Link Attributes represent layer resource capabilities and
their utilization i.e. the IGP should be able to advertise these their utilization i.e. the IGP should be able to advertise these
attributes on a per-layer basis. attributes on a per-layer basis.
5.3.2 Node Attributes 5.3.2 Node Attributes
Nodes attributes are the "Logical Node ID" (as detailed in Section Node attributes are the "Logical Node ID" (described in Section 5.1)
5.1) and the reachability information as described in Section 5.3.3. and the reachability information described in Section 5.3.3.
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5.3.3 Reachability Information 5.3.3 Reachability Information
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Advertisement of reachability can be achieved using the techniques Advertisement of reachability can be achieved using the techniques
described in [OSPF-NODE] where the set of local addresses are described in [OSPF-NODE] where the set of local addresses are
carried in an OSPF TE LSA node attribute TLV (a specific sub-TLV is carried in an OSPF TE LSA node attribute TLV (a specific sub-TLV is
defined per address family, e.g., IPv4 and IPv6). However, [OSPF- defined per address family, e.g., IPv4 and IPv6). However, [OSPF-
NODE] is restricted to advertisement of Host addresses and not NODE] is restricted to advertisement of Host addresses and not
prefixes, and therefore requires enhancement (see below). Hence, in prefixes, and therefore requires enhancement (see below). Hence, in
order to advertise blocks of reachable address prefixes a order to advertise blocks of reachable address prefixes a
summarization mechanism is additionally required. This mechanism may summarization mechanism is additionally required. This mechanism may
take the form of a prefix length (that indicates the number of take the form of a prefix length (that indicates the number of
significant bits in the prefix) or a network mask. significant bits in the prefix) or a network mask.
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A similar mechanism does not exist for IS-IS. Moreover, the Extended A similar mechanism does not exist for IS-IS. Moreover, the Extended
IP Reachability TLV [RFC3784] focuses on IP reachable end-points IP Reachability TLV [RFC3784] focuses on IP reachable end-points
(terminating points), as its name indicates. (terminating points), as its name indicates.
5.4 Routing Information Abstraction 5.4 Routing Information Abstraction
G.7715.1 describes both static and dynamic methods for abstraction of G.7715.1 describes both static and dynamic methods for abstraction of
routing information for advertisement at a different level of the routing information for advertisement at a different level of the
routing hierarchy. However, the information that is advertised routing hierarchy. However, the information that is advertised
continues to be in the form of link and node advertisements continues to be in the form of link and node advertisements
consistent with the link state routing protocol used at that level, consistent with the link state routing protocol used at that level.
hence no specific capabilities need to be added to the routing Hence, no specific capabilities need to be added to the routing
protocol beyond the ability to locally identify when routing protocol beyond the ability to locally identify when routing
information originates outside of a particular RA. information originates outside of a particular RA.
The methods used for abstraction of routing information are outside The methods used for abstraction of routing information are outside
the scope of GMPLS routing protocols. the scope of GMPLS routing protocols.
5.5 Dissemination of routing information in support of multiple 5.5 Dissemination of routing information in support of multiple
hierarchical levels of RAs hierarchical levels of RAs
G.7715.1 does not define specific mechanisms to support multiple G.7715.1 does not define specific mechanisms to support multiple
hierarchical levels of RAs, beyond the ability to support abstraction hierarchical levels of RAs, beyond the ability to support abstraction
as discussed above. However, if RCs bound to adjacent levels of the as discussed above. However, if RCs bound to adjacent levels of the
RA hierarchy were allowed to redistribute routing information in RA hierarchy are allowed to redistribute routing information in both
both directions between adjacent levels of the hierarchy without any directions between adjacent levels of the hierarchy without any
additional mechanisms, they would not be able to determine looping additional mechanisms, they would not be able to determine looping
of routing information. of routing information.
To prevent this looping of routing information between levels, IS-IS To prevent this looping of routing information between levels, IS-IS
[RFC1195] allows only advertising routing information upward in the [RFC1195] allows only advertising routing information upward in the
level hierarchy, and disallows the advertising of routing level hierarchy, and disallows the advertising of routing
information downward in the hierarchy. [RFC2966] defines the up/down information downward in the hierarchy. [RFC2966] defines the up/down
bit to allow advertising downward in the hierarchy the "IP Internal bit to allow advertising downward in the hierarchy the "IP Internal
Reachability Information" TLV (Type 128) and "IP External Reachability Information" TLV (Type 128) and "IP External
Reachability Information" TLV (Type 130). [RFC3784] extends its Reachability Information" TLV (Type 130). [RFC3784] extends its
applicability for the "Extended IP Reachability" TLV (Type 135). applicability for the "Extended IP Reachability" TLV (Type 135).
Using this mechanism, the up/down bit is set to 0 when routing Using this mechanism, the up/down bit is set to 0 when routing
C.Hopps et al. - Expires January 2006 8
information is first injected into IS-IS. If routing information is information is first injected into IS-IS. If routing information is
advertised from a higher level to a lower level, the up/down bit is advertised from a higher level to a lower level, the up/down bit is
set to 1, indicating that it has traveled down the hierarchy. set to 1, indicating that it has traveled down the hierarchy.
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Routing information that has the up/down bit set to 1 may only be Routing information that has the up/down bit set to 1 may only be
advertised down the hierarchy, i.e. to lower levels. This mechanism advertised down the hierarchy, i.e. to lower levels. This mechanism
applies independently of the number of levels. However, this applies independently of the number of levels. However, this
mechanism does not apply to the "Extended IS Reachability" TLV (Type mechanism does not apply to the "Extended IS Reachability" TLV (Type
22) used to propagate the summarized topology (see Section 5.3), 22) used to propagate the summarized topology (see Section 5.3),
traffic engineering information as listed in Table 1, as well as traffic engineering information as listed in Table 1, as well as
reachability information (see Section 5.3.3). reachability information (see Section 5.3.3).
OSPFv2 [RFC2328] prevents inter-area routes (which are learned from OSPFv2 [RFC2328] prevents inter-area routes (which are learned from
area 0) from being passed back to area 0. However, GMPLS makes use of area 0) from being passed back to area 0. However, GMPLS makes use of
skipping to change at line 463 skipping to change at line 462
minimum of routing information exchange. minimum of routing information exchange.
Therefore, existing routing protocol convergence involves mechanisms Therefore, existing routing protocol convergence involves mechanisms
are sufficient for ASON applications. are sufficient for ASON applications.
5.7 Routing Information Scoping 5.7 Routing Information Scoping
The routing protocol MUST support a single Ri advertising on behalf The routing protocol MUST support a single Ri advertising on behalf
of more than one Li. Since each Li is identified by a unique of more than one Li. Since each Li is identified by a unique
TE Router ID, the routing protocol MUST be able to advertise TE Router ID, the routing protocol MUST be able to advertise
multiple TE Router IDs. That is for [RFC3630] multiple Router multiple TE Router IDs. That is, for [RFC3630], multiple Router
Addresses and for [RFC3784] multiple Traffic Engineering Router Ids. Addresses and for [RFC3784] multiple Traffic Engineering Router Ids.
The Link sub-TLV currently part of the top level Link TLV associates The Link sub-TLV currently part of the top level Link TLV associates
the link to the Router_ID. However, having the Ri advertising on the link to the Router_ID. However, having the Ri advertising on
behalf multiple Li's creates the following issue as there is no behalf of multiple Li's creates the following issue, as there is no
longer a 1:1 relationship between the Router_ID and the TE Router_ID longer a 1:1 relationship between the Router_ID and the TE
but a 1:N relationship is possible (see Section 5.1). As the link Router_ID, but a 1:N relationship is possible (see Section 5.1). As
local and link remote (unnumbered) ID association may be not unique the link local and link remote (unnumbered) ID association may be
per abstract node (per Li unicity), the advertisement needs to not unique per abstract node (per Li unicity), the advertisement
indicate the remote Lj value and rely on the initial discovery needs to indicate the remote Lj value and rely on the initial
process to retrieve the {Li;Lj} relationship(s). In brief, as discovery process to retrieve the {Li;Lj} relationship(s). In brief,
unnumbered links have their ID defined on per Li bases, the remote as unnumbered links have their ID defined on per Li bases, the
Lj needs to be identified to scope the link remote ID to the local remote Lj needs to be identified to scope the link remote ID to the
Li. Therefore, the routing protocol MUST be able to disambiguate the
advertised TE links so that they can be associated with the correct
TE Router ID.
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local Li. Therefore, the routing protocol MUST be able to
disambiguate the advertised TE links so that they can be associated
with the correct TE Router ID.
Moreover, when the Ri advertises on behalf multiple Li's, the Moreover, when the Ri advertises on behalf multiple Li's, the
routing protocol MUST be able to disambiguate the advertised routing protocol MUST be able to disambiguate the advertised
reachability information (see Section 5.3.3) so that it can be reachability information (see Section 5.3.3) so that it can be
associated with the correct TE Router ID. associated with the correct TE Router ID.
6. Evaluation Scenarios 6. Evaluation Scenarios
The evaluation scenarios are the following; they are respectively The evaluation scenarios are the following; they are respectively
referred to as case 1, 2, 3, and 4. referred to as case 1, 2, 3, and 4.
skipping to change at line 530 skipping to change at line 530
| | | | | | | |
| L1 | | L2 | | L1 | | L2 |
| : | | : | | : | | : |
| : R1| | : R2| | : R1| | : R2|
Control Plane --+--- --+--- Control Plane --+--- --+---
Elements : : Elements : :
------------------+-----------------------------+------------------ ------------------+-----------------------------+------------------
Data Plane : : Data Plane : :
Elements : : Elements : :
----+-----------------------------+----- ----+-----------------------------+-----
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| : : | | : : |
| --- --- --- | | --- --- --- |
| | |----------| P |----------| | | | | |----------| P |----------| | |
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---+--| | --- | |---+--- ---+--| | --- | |---+---
| | | | | | | | | | | |
| | P1|-------------------------| P2| | | | P1|-------------------------| P2| |
| --- --- | | --- --- |
---------------------------------------- ----------------------------------------
Figure 2. Case 1 with Logical Links Figure 2. Case 1 with Logical Links
Another case (referred to as Case 4) is constituted by the Abstract Another case (referred to as Case 4) is constituted by the Abstract
Node as represented in Figure 3. There is no internal structure Node as represented in Figure 3. There is no internal structure
skipping to change at line 573 skipping to change at line 573
Figure 3. Case 4: Abstract Node Figure 3. Case 4: Abstract Node
Note: the "signaling function" i.e. the control plane entity that Note: the "signaling function" i.e. the control plane entity that
processes the signaling messages (referred to as Si) is not processes the signaling messages (referred to as Si) is not
represented in these Figures. represented in these Figures.
7. Summary of Necessary Additions to OSPF and IS-IS 7. Summary of Necessary Additions to OSPF and IS-IS
The following sections summarize the additions to be provided to The following sections summarize the additions to be provided to
OSPF and IS-IS in support of ASON routing OSPF and IS-IS in support of ASON routing.
7.1 OSPFv2 7.1 OSPFv2
Reachability Extend Node Attribute sub-TLVs to support Reachability Extend Node Attribute sub-TLVs to support
address prefixes (see Section 5.3.3) address prefixes (see Section 5.3.3)
Link Attributes Representation of cross/inter-layer Link Attributes Representation of cross/inter-layer
relationships in link top-level link TLV (see relationships in link top-level link TLV (see
Section 5.3.1) Section 5.3.1)
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Optionally, provide for per signal-type Optionally, provide for per signal-type
bandwidth accounting (see Section 5.3.1). bandwidth accounting (see Section 5.3.1).
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Scoping TE link advertisements to allow for retrieving Scoping TE link advertisements to allow for retrieving
their respective local-remote TE Router_ID their respective local-remote TE Router_ID
relationship(s) (see Section 5.7) relationship(s) (see Section 5.7)
Prefixes part of the reachability Prefixes part of the reachability
advertisements (using Node Attribute top level advertisements (using Node Attribute top level
TLV) needs to be associated to their respective TLV) needs to be associated to their respective
local TE Router_ID (see Section 5.7) local TE Router_ID (see Section 5.7)
Hierarchy Provide a mechanism by which Type 10 Opaque LSA Hierarchy Provide a mechanism by which Type 10 Opaque LSA
skipping to change at line 630 skipping to change at line 630
Prefixes part of the reachability advertisements Prefixes part of the reachability advertisements
needs to be associated to their respective local needs to be associated to their respective local
TE Router_ID (see Section 5.7) TE Router_ID (see Section 5.7)
Hierarchy Extend the up/down bit mechanisms to propagate Hierarchy Extend the up/down bit mechanisms to propagate
the summarized topology (see Section 5.3), the summarized topology (see Section 5.3),
traffic engineering information as listed in traffic engineering information as listed in
Table 1, as well as reachability information Table 1, as well as reachability information
(see Section 5.3.3). (see Section 5.3.3).
8. Acknowledgements 8. Security Considerations
The introduction of a dynamic control plane to an ASON network
exposes it to additional security risks that may have been
controlled or limited by the use of management plane solutions. The
routing protocols play a part in the control plane and may be
C.Hopps et al. - Expires January 2006 12
attacked so that they are unstable, or provide incorrect information
for use in path computation or by the signaling protocols.
Nevertheless, there is no reason why the control plane components
cannot be secured, and the security mechanisms developed for the
routing protocol and used within the Internet are equally applicable
within an ASON context.
[RFC4258] describes the requirements for security of routing
protocols for the Automatically Switched Optical Network. Reference
is made to [M.3016] that lays out the overall security objectives of
confidentiality, integrity, and accountability, and these are well
discussed for the Internet routing protocols in [THREATS].
A detailed discussion of routing threats and mechanisms, which are
currently deployed in operational networks to counter these
threats, is found in [OPSECPRACTICES]. A detailed listing of the
device capabilities that can be used to support these practices can
be found in [RFC3871].
9. IANA Considerations
This draft makes no requests for IANA action.
10. Acknowledgements
The authors would like to thank Adrian Farrel for having initiated The authors would like to thank Adrian Farrel for having initiated
the proposal of an ASON Routing Solution Design Team and the ITU-T the proposal of an ASON Routing Solution Design Team and the ITU-T
SG15/Q14 for their careful review and input. SG15/Q14 for their careful review and input.
9. References 11. References
9.1 Normative References
C.Hopps et al. - Expires January 2006 12 11.1 Normative References
[ASON-RR] W.Alanqar et al. "Requirements for Generalized MPLS
(GMPLS) Routing for Automatically Switched Optical
Network (ASON)," Work in progress, draft-ietf-ccamp-
gmpls-ason-routing-reqts-05.txt, October 2004.
[RFC1195] R.Callon, "Use of OSI IS-IS for Routing in TCP/IP and [RFC1195] R.Callon, "Use of OSI IS-IS for Routing in TCP/IP and
Dual Environments", RFC 1195, December 1990. Dual Environments", RFC 1195, December 1990.
[RFC2966] T.Li, T. Przygienda, and H. Smit et al. "Domain-wide [RFC2966] T.Li, T. Przygienda, and H. Smit et al. "Domain-wide
Prefix Distribution with Two-Level IS-IS", RFC 2966, Prefix Distribution with Two-Level IS-IS", RFC 2966,
October 2000. October 2000.
[RFC2026] S.Bradner, "The Internet Standards Process --
Revision 3", BCP 9, RFC 2026, October 1996.
[RFC2328] J.Moy, "OSPF Version 2", RFC 2328, April 1998. [RFC2328] J.Moy, "OSPF Version 2", RFC 2328, April 1998.
[RFC2119] S.Bradner, "Key words for use in RFCs to Indicate [RFC2119] 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.
[RFC3477] K.Kompella et al. "Signalling Unnumbered Links in [RFC3477] K.Kompella et al. "Signalling Unnumbered Links in
Resource ReSerVation Protocol - Traffic Engineering Resource ReSerVation Protocol - Traffic Engineering
(RSVP-TE)", RFC 3477, January 2003. (RSVP-TE)", RFC 3477, January 2003.
[RFC3630] D.Katz et al. "Traffic Engineering (TE) Extensions to [RFC3630] D.Katz et al. "Traffic Engineering (TE) Extensions to
OSPF Version 2", RFC 3630, September 2003. OSPF Version 2", RFC 3630, September 2003.
C.Hopps et al. - Expires January 2006 13
[RFC3784] H.Smit and T.Li, "Intermediate System to Intermediate [RFC3784] H.Smit and T.Li, "Intermediate System to Intermediate
System (IS-IS) Extensions for Traffic Engineering (TE)," System (IS-IS) Extensions for Traffic Engineering (TE),"
RFC 3784, June 2004. RFC 3784, June 2004.
[RFC3871] G.Jones, Ed., "Operational Security Requirements for
Large Internet Service Provider (ISP) IP Network
Infrastructure", RFC 3871, September 2004.
[RFC3946] E.Mannie, and D.Papadimitriou, (Editors) et al., [RFC3946] E.Mannie, and D.Papadimitriou, (Editors) et al.,
"Generalized Multi-Protocol Label Switching Extensions "Generalized Multi-Protocol Label Switching Extensions
for SONET and SDH Control," RFC 3946, October 2004. for SONET and SDH Control," RFC 3946, October 2004.
[RFC4202] Kompella, K. (Editor) et al., "Routing Extensions in [RFC4202] K.Kompella (Editor) et al., "Routing Extensions in
Support of Generalized Multi-Protocol Label Switching Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4202, October 2005. (GMPLS)", RFC 4202, October 2005.
[RFC4203] K. Kompella, Y. Rekhter, et al, "OSPF Extensions in [RFC4203] K. Kompella, Y. Rekhter, et al, "OSPF Extensions in
Support of Generalized Multi-Protocol Label Switching Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4203, October 2005. (GMPLS)", RFC 4203, October 2005.
[RFC4205] K. Kompella, Y. Rekhter, et al, "Intermediate System [RFC4205] K. Kompella, Y. Rekhter, et al, "Intermediate System
to Intermediate System (IS-IS) Extensions in Support to Intermediate System (IS-IS) Extensions in Support
of Generalized Multi-Protocol Label Switching (GMPLS)", of Generalized Multi-Protocol Label Switching (GMPLS)",
RFC 4205, October 2005. RFC 4205, October 2005.
9.2 Informative References [RFC4258] D.Brungard et al. "Requirements for Generalized MPLS
(GMPLS) Routing for Automatically Switched Optical
Network (ASON)," RFC 4258, November 2005.
C.Hopps et al. - Expires January 2006 13 11.2 Informative References
[LMP-T] D.Fedyk et al., "A Transport Network View of LMP,"
Internet Draft (work in progress), draft-ietf-ccamp- [RFC4394] D.Fedyk et al., "A Transport Network View of the Link
transport-lmp-02, May 2005. Management Protocol (LMP)," RFC 4394, February 2006.
[OPSECPRACTICES] M.Kaeo, "Operational Security Current Practices",
Internet Draft (Work in progress), draft-ietf-opsec-
current-practices-02.txt, October 2005.
[OSPF-NODE] R.Aggarwal, and K.Kompella, "Advertising a Router's [OSPF-NODE] R.Aggarwal, and K.Kompella, "Advertising a Router's
Local Addresses in OSPF TE Extensions," Internet Draft, Local Addresses in OSPF TE Extensions," Internet Draft,
(work in progress), draft-ietf-ospf-te-node-addr- (work in progress), draft-ietf-ospf-te-node-addr-
02.txt, March 2005. 02.txt, March 2005.
[THREATS] A.Barbir et al., "Generic Threats to Routing
Protocols", Internet Draft (work in progress), draft-
ietf-rpsec-routing-threats-07.txt, October 2004.
For information on the availability of ITU Documents, please see For information on the availability of ITU Documents, please see
http://www.itu.int http://www.itu.int
[G.7715] ITU-T Rec. G.7715/Y.1306, "Architecture and [G.7715] ITU-T Rec. G.7715/Y.1306, "Architecture and
C.Hopps et al. - Expires January 2006 14
Requirements for the Automatically Switched Optical Requirements for the Automatically Switched Optical
Network (ASON)," June 2002. Network (ASON)," June 2002.
[G.7715.1] ITU-T Draft Rec. G.7715.1/Y.1706.1, "ASON Routing [G.7715.1] ITU-T Draft Rec. G.7715.1/Y.1706.1, "ASON Routing
Architecture and Requirements for Link State Protocols," Architecture and Requirements for Link State Protocols,"
November 2003. November 2003.
[G.8080] ITU-T Rec. G.8080/Y.1304, "Architecture for the [G.8080] ITU-T Rec. G.8080/Y.1304, "Architecture for the
Automatically Switched Optical Network (ASON)," Automatically Switched Optical Network (ASON),"
November 2001 (and Revision, January 2003). November 2001 (and Revision, January 2003).
10. Author's Addresses 11. Author's Addresses
Lyndon Ong (Ciena Corporation) Lyndon Ong (Ciena Corporation)
PO Box 308 PO Box 308
Cupertino, CA 95015 , USA Cupertino, CA 95015 , USA
Phone: +1 408 705 2978 Phone: +1 408 705 2978
EMail: lyong@ciena.com EMail: lyong@ciena.com
Dimitri Papadimitriou (Alcatel) Dimitri Papadimitriou (Alcatel)
Francis Wellensplein 1, Francis Wellensplein 1,
B-2018 Antwerpen, Belgium B-2018 Antwerpen, Belgium
skipping to change at line 744 skipping to change at line 784
Stephen Shew (Nortel Networks) Stephen Shew (Nortel Networks)
PO Box 3511 Station C PO Box 3511 Station C
Ottawa, Ontario, CANADA K1Y 4H7 Ottawa, Ontario, CANADA K1Y 4H7
Phone: +1 613 7632462 Phone: +1 613 7632462
EMail: sdshew@nortelnetworks.com EMail: sdshew@nortelnetworks.com
Dave Ward (Cisco Systems) Dave Ward (Cisco Systems)
170 W. Tasman Dr. 170 W. Tasman Dr.
San Jose, CA 95134 USA San Jose, CA 95134 USA
C.Hopps et al. - Expires January 2006 14
Phone: +1-408-526-4000 Phone: +1-408-526-4000
EMail: dward@cisco.com EMail: dward@cisco.com
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Appendix 1: ASON Terminology Appendix 1: ASON Terminology
This document makes use of the following terms: This document makes use of the following terms:
Administrative domain: (see Recommendation G.805) for the purposes of Administrative domain: (see Recommendation G.805) for the purposes of
skipping to change at line 907 skipping to change at line 945
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 AND THE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE
INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement Copyright Statement
Copyright (C) The Internet Society (2005). This document is subject Copyright (C) The Internet Society (2006). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights. except as set forth therein, the authors retain all their rights.
Acknowledgment Acknowledgment
Funding for the RFC Editor function is currently provided by the Funding for the RFC Editor function is currently provided by the
Internet Society. Internet Society.
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