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draft-ietf-ccamp-gmpls-ason-routing-ospf
CCAMP Working Group Dimitri Papadimitriou
Internet Draft (Alcatel)
Category: Standard
Expiration Date: December 2006 June 2006
OSPFv2 Routing Protocols Extensions for ASON Routing
draft-dimitri-ccamp-gmpls-ason-routing-ospf-00.txt
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Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
The Generalized MPLS (GMPLS) suite of protocols has been defined to
control different switching technologies as well as different
applications. These include support for requesting TDM connections
including SONET/SDH and Optical Transport Networks (OTNs).
This document provides the extensions of the OSPFv2 Link State
Routing Protocol to meet the routing requirements for an
Automatically Switched Optical Network (ASON) as defined by ITU-T.
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1. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
The reader is assumed to be familiar with the terminology and
requirements developed in [ASON-RR] and the evaluation outcomes
detailed in [ASON-EVAL].
2. Introduction
There are certain capabilities that are needed to support the ITU-T
Automatically Switched Optical Network (ASON) control plane
architecture as defined in [G.8080]. [ASON-RR] details the routing
requirements for the GMPLS suite of routing protocols to support the
capabilities and functionality of ASON control planes identified in
[G.7715] and in [G.7715.1].
[ASON-EVAL] evaluates the IETF Link State Routing Protocols against
the requirements identified in [ASON-RR]. Candidate routing protocols
are IGP (OSPFv2 and IS-IS). This document details the OSPFv2
specifics for ASON routing.
ASON (Routing) terminology sections are provided in Appendix 1 and 2.
3. Reachability
In order to advertise blocks of reachable address prefixes a
summarization mechanism is introduced that complements the
techniques described in [OSPF-NODE].
This extension takes the form of a network mask (a 32-bit number
indicating the range of IP addresses residing on a single IP
network/subnet). The set of local addresses are carried in an OSPFv2
TE LSA node attribute TLV (a specific sub-TLV is defined per address
family, e.g., IPv4 and IPv6).
The proposed solution is to advertise the local address prefixes of
a router as new sub-TLVs of the (OSPFv2 TE LSA) Node Attribute top
level TLV (of Type TBD). This document defines the following sub-
TLVs:
- Node IPv4 Local Prefix sub-TLV: Type 3 - Length: variable
- Node IPv6 Local Prefix sub-TLV: Type 4 - Length: variable
3.1 Node IPv4 local prefix sub-TLV
The node IPv4 local prefix sub-TLV has a type of 3 and contains one
or more local IPv4 prefixes. It has the following format:
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 3 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Network Mask 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Address 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . .
. . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Network Mask n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Address n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The length is set to 8 * n where n is the number of local prefixes
included in the sub-TLV.
Network mask: A 32-bit number indicating the IPv4 address mask
for the advertised destination prefix.
Each <Network mask, IPv4 Address> pair listed as part of this sub-
TLV represents a reachable destination prefix hosted by the
advertising Router ID.
The local addresses that can be learned from TE LSAs i.e. router
address and TE interface addresses SHOULD not be advertised in the
node IPv4 local prefix sub-TLV.
3.2 Node IPv6 local prefix sub-TLV
The node IPv6 local prefix sub-TLV has a type of 4 and contains one
or more local IPv6 prefixes. IPv6 Prefix Representation uses RFC
2740 Section A.4.1. It has the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 4 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PrefixLength | PrefixOptions | (0) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| IPv6 Address Prefix 1 |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . .
. . .
. . .
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PrefixLength | PrefixOptions | (0) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| IPv6 Address Prefix n |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
PrefixLength: length in bits of the prefix.
PrefixOptions: 8-bit field describing various capabilities
associated with the prefix (see [RFC2740] Section A.4.2).
Address Prefix: encoding of the prefix itself as an even multiple of
32-bit words, padding with zero bits as necessary.
The Length is set to Sum[n][4 + #32-bit words/4] where n is the
number of local prefixes included in the sub-TLV.
The local addresses that can be learned from TE LSAs i.e. router
address and TE interface addresses SHOULD not be advertised in the
node IPv6 local prefix sub-TLV.
4. Link Attribute
4.1 Local Adaptation
The Local Adaptation is defined as TE link attribute (i.e. sub-TLV)
that describes the cross/inter-layer relationships.
The Interface Switching Capability Descriptor (ISCD) TE Attribute
[RFC4202] identifies the ability of the TE link to support cross-
connection to another link within the same layer and the ability to
use a locally terminated connection that belongs to one layer as a
data link for another layer (adaptation capability). However, the
information associated to the ability to terminate connections
within that layer (referred to as the termination capability) is
embedded with the adaptation capability.
For instance, a link between two optical cross-connects will contain
at least one ISCD attribute describing LSC switching capability.
Whereas a link between an optical cross-connect and an IP/MPLS LSR
will contain at least two ISCD attributes: one for the description
of the LSC termination capability and one for the PSC adaptation
capability.
Note that per [RFC4202], an interface may have more than one ISCD
sub-TLV. Hence, the corresponding advertisements should not result
in any compatibility issue.
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In OSPFv2, the Interface Switching Capability Descriptor is a sub-
TLV (of type 15) of the top-level Link TLV (of type 2) [RFC4203].
The adaptation and termination capabilities are advertised using two
separate ISCD sub-TLVs within the same top-level link TLV.
4.2 Technology Specific Bandwidth Accounting
GMPLS Routing defines an Interface Switching Capability Descriptor
(ISCD) that delivers among others the information about the
(maximum/minimum) bandwidth per priority an LSP can make use of.
In the ASON context, accounting on per timeslot basis using 32-bit
tuples of the form <signal_type (8 bits); number of unallocated
timeslots (24 bits)> may optionally be incorporated in the
technology specific field of the ISCD TE link attribute when the
switching capability field is set to TDM value. When included,
format and encoding MUST follow the rules defined in [RFC4202].
The purpose is purely informative: there is no mandatory processing
or topology/traffic-engineering significance associated to this
information.
In OSPF, the Interface Switching Capability Descriptor is a sub-TLV
(of type 15) of the Link TLV (of type 2).
5. Routing Information Scope
The Ri is a logical control plane entity that is associated to a
control plane "router". The latter is the source for topology
information that it generates and shares with other control plane
"routers". The Ri is identified by the (advertising) Router_ID. The
routing protocol MUST support a single Ri advertising on behalf of
more than one Li. Each Li is identified by a unique TE Router ID.
5.1 Link Advertisement (Local and Remote TE Router ID sub-TLV)
A Router_ID (Ri) advertising on behalf multiple TE Router_ID (Li's)
creates a 1:N relationship between the Router_ID and the TE
Router_ID. As the link local and link remote (unnumbered) ID
association is not unique per node (per Li unicity), the
advertisement needs to indicate the remote Lj value and rely on the
initial discovery process to retrieve the [Li;Lj] relationship. In
brief, as unnumbered links have their ID defined on per Li bases,
the remote Lj needs to be identified to scope the link remote ID to
the 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.
For this purpose, a new sub-TLV of the (OSPFv2 TE LSA) top level
Link TLV is introduced that defines the local and the remote
TE_Router_ID.
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The type of this sub-TLV is 17, and length is eight octets. The
value field of this sub-TLV contains four octets of Local TE Router
Identifier followed by four octets of Remote TE Router Identifier.
The value of the Remote TE Router Identifier SHOULD NOT be set to 0.
The format of this sub-TLV is the following:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 17 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local TE Router Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote TE Router Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This sub-TLV is optional and SHOULD only be included as part of the
top level Link TLV if the Router_ID is advertising on behalf of more
than one TE_Router_ID. In any other case, this sub-TLV SHOULD be
omitted.
Note: The Link ID sub-TLV that identifies the other end of the link
(i.e. Router ID of the neighbor for point-to-point links) MUST
appear exactly once per Link TLV.
5.2 Reachability Advertisement (Local TE Router ID sub-TLV)
When the Router_ID advertises on behalf of multiple TE Router_IDs,
the routing protocol MUST be able to associate the advertised
reachability information with the correct TE Router ID.
For this purpose, a new sub-TLV of the (OSPFv2 TE LSA) top level
Node Attribute TLV is introduced. This TLV associates the local
prefixes (sub-TLV 3 and 4, see above) to a given TE Router_ID.
The type of this sub-TLV is 5, and length is four octets. The value
field of this sub-TLV contains four octets of Local TE Router
Identifier [RFC3630].
The format of this sub-TLV is the following:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 5 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local TE Router Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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This sub-TLV is optional and SHOULD only be included as part of the
Node Attribute TLV if the Router_ID is advertising on behalf of more
than one TE_Router_ID. In any other case, this sub-TLV SHOULD be
omitted.
6. Routing Information Dissemination
RC disseminates downward/upward the hierarchy by re-originating this
routing information as Opaque TE LSA (Opaque Type 1) of LS Type 10.
The information that MAY be exchanged between adjacent levels
includes the Router_Address, Link and Node_Attribute top level TLV.
The Opaque TE LSA re-origination is governed as follows:
- If the target interface is associated to the same area as the
one associated with the receiving interface, the Opaque LSA MUST
NOT be re-originated out that interface.
- If a match is found between the Advertising Router ID in the
header of the received Opaque TE LSA and one of the Router ID
belonging to the area of the target interface, the Opaque LSA MUST
NOT be re-originated out that interface.
- If these two conditions are not met the Opaque TE LSA MAY be re-
originated.
The re-originated content MAY be transformed e.g. filtered, as long
as the resulting routing information is consistent. In particular,
when more than one RC are bound to adjacent levels and both are
allowed to redistribute routing information it is expected that
these transformation are performed in consistent manner. Definition
of these policy mechanisms is outside the scope of this document.
In practice, and in order to avoid scalability and processing
overhead, routing information re-distributed downward/upward the
hierarchy is expected to include reachability information (see
Section 3) and upon strict policy control link topology information.
6.1 Discovery and Selection
In order to discover RCs that are capable to disseminate routing
information upward the routing hierarchy, the following Capability
Descriptor bit [OSPF-CAP] are defined:
- U bit: when set, this flag indicates that the RC is capable to
disseminate routing information upward the adjacent level.
In case of multiple RC are advertized with their U bit set, the RC
with the highest Router ID, among the RCs having set the U bit,
SHOULD be selected as the RC for upward dissemination of routing
information. The other RCs MUST NOT participate in the upward
dissemination of routing information as long as the opaque LSA
information corresponding to the highest Router ID RC does not reach
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MaxAge. This mechanism prevents from having more than one RC
advertizing routing information upward the routing hierarchy.
Note that alternatively if this information cannot be discovered
automatically, it MUST be manually configured.
The same discovery - not election - mechanism is used for selecting
the RC taking in charge dissemination of routing information
downward the hierarchy. However, an additional restriction MUST be
applied such that the RC selection process takes into account that
an upper level may be adjacent to one or more lower levels. For this
purpose a specific TLV indexing the (lower) area ID to which the
RC's are capable to disseminate routing information is needed.
OSPF Associated Area ID TLV format carried in the OSPF router
information LSA [OSPF-CAP] is defined. This TLV has the following
format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Associated Area ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type (16 bits): identifies the TLV type
Length (16 bits): length of the value field in octets
Value (32 bits): Associated Area ID whose value space is the Area ID
as defined in [RFC2328].
Note that this information MUST be present when the D bit is set. To
discover RCs that are capable to disseminate routing information
downward the routing hierarchy, the following Capability Descriptor
bit [OSPF-CAP] is defined, that MUST be advertised together with the
OSPF Area ID TLV:
- D bit: when set, this flag indicates that the RC is capable to
disseminate routing information downward the adjacent level.
In case of multiple supporting RCs for the same Associated Area ID,
the RC with the highest Router ID, among the RCs having set the D
bit, MUST be selected as the RC for downward dissemination of
routing information. The other RCs for the same Associated Area ID
MUST not participate in the downward dissemination of routing
information as long as the opaque LSA information corresponding to
the highest Router ID RC does not reach MaxAge. This mechanism
prevents from having more than one RC advertizing routing
information downward the routing hierarchy.
Note that alternatively if this information cannot be discovered
automatically, it MUST be manually configured.
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The OSPF Router information opaque LSA (opaque type of 4, opaque ID
of 0) and its content in particular, the Router Informational
Capabilities TLV [OSPF-CAP] and TE Node Capability Descriptor TLV
[OSPF-TE-CAP] MUST NOT be re-originated.
6.2 Loop prevention
When more than one RC are bound to adjacent levels of the hierarchy,
configured and selected to redistribute upward and downward the
routing information, a specific mechanism is required to avoid
looping/re-introduction of routing information back to the upper
level. This specific case occurs when the RC advertizing routing
information downward the hierarchy is not the one advertizing
routing upward the hierarchy (or vice-versa).
In all other cases, the procedure described in this section SHOULD
NOT be applied.
When these conditions are met, it is necessary to have a mean by
which an RC receiving an Opaque TE LSA re-originated downward by an
RC associated to the same area omits to re-originate back the
content of this LSA upward into the (same) upper level.
6.2.1 Associated Area ID
Thus we need some way of filtering the downward/onward re-originated
Opaque TE LSA. Per [RFC2370], the information contained in Opaque
LSAs may be used directly by OSPF. Henceforth, by adding the Area ID
associated to the incoming routing information the loop prevention
problem can be solved. This additional information carried in opaque
LSAs including the Router Address TLV, opaque LSAs including the
Link TLV, and opaque LSAs including the Node Attribute TLV is
referred to as the Associated Area ID.
The format of the Associated Area ID TLV is defined as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Associated Area ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type (16 bits): identifies the TLV type
Length (16 bits): length of the value field in octets
Value (32 bits): Associated Area ID whose value space is the Area ID
as defined in [RFC2328].
6.2.2 Processing
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When fulfilling the rules detailed in Section 6.0 a given Opaque LSA
is re-originated downward or upward the routing hierarchy, the
Associated Area ID TLV is added to the received opaque LSA list of
TLVs such as to identify the area from where this routing
information has been received.
When the RC adjacent to the lower or upper level routing level
receives this opaque LSA, the following rule is applied (in addition
the rule governing the re-origination of opaque LSAs as detailed in
Section 6.0).
- If a match is found between the Associated Area ID of the received
Opaque TE LSA and the Area ID belonging to the area of the target
interface, the Opaque LSA MUST NOT be re-originated out that
interface.
- Otherwise, this opaque LSA MAY be originated downward or upward
the routing hierarchy.
This mechanism ensures that no race condition occurs in the
following conditions for instance:
RC_5 ---------- RC_6
| | Area Y
| |
========== RC_1 ========== RC_2 ==========
| |
| | Area X
RC_3 --- .. --- RC_4
Assume that RC_1 is configured for exchanging routing information
upward toward Area Y (upward the routing hierarchy) and that RC_2 is
configured for exchanging routing information toward Area X
(downward the routing hierarchy).
Assumes that RC_3 advertized routing information would reach faster
to RC_4 across Area Y.
If RC_2 is not able to prevent from re-originating that information,
RC_4 may receive that information before the same advertisement
would propagate to RC_4.
7. OSPFv2 Extensions
7.1 Compatibility
Extensions specified in this document are associated to the
Opaque TE LSA:
o) Router Address top level TLV (Type 1):
- Associated Area ID sub-TLV: optional sub-TLV for loop avoidance
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(see Section 6.2)
o) Link top level TLV (Type 2):
- Local and Remote TE Router ID sub-TLV: optional sub-TLV for
scoping link attributes per TE_Router ID
- Associated Area ID sub-TLV: optional sub-TLV for loop avoidance
(see Section 6.2)
o) Node Attribute top level TLV (Type TBD):
- Node IPv4 Local Prefix sub-TLVs: optional sub-TLV for IPv4
reachability advertisement
- Node IPv6 Local Prefix sub-TLVs: optional sub-TLV for IPv6
reachability advertisement
- Local TE Router ID sub-TLV: optional sub-TLV for scoping
reachability per TE_Router ID
- Associated Area ID sub-TLV: optional sub-TLV for loop avoidance
(see Section 6.2)
Opaque RI LSA:
o) Routing information dissemination
- U and D bit in Capability Descriptor TLV [OSPF-CAP]
- Associated Area ID TLV in the OSPF Routing Information LSA
[OSPF-CAP]
7.2 Scalability
o) Routing information exchange upward/downward the hierarchy
between adjacent areas SHOULD by default be limited to reachability.
In addition, several transformation such as prefix aggregation are
recommended when allowing decreasing the amount of information re-
originated by a given RC without impacting consistency.
o) Routing information exchange upward/downward the hierarchy when
involving TE attributes MUST be under strict policy control. Pacing
and min/max thresholds for triggered updates are strongly
recommended.
8. Acknowledgements
The authors would like to thank Pandian Vijay, Alan Davey and Adrian
Farrel for their useful comments and suggestions.
9. References
9.1 Normative References
[OSPF-NODE] R.Aggarwal, and K.Kompella, "Advertising a Router's
Local Addresses in OSPF TE Extensions," Internet Draft,
(work in progress), draft-ietf-ospf-te-node-addr-
02.txt, March 2005.
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[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.
[RFC2370] R.Coltun, "The OSPF Opaque LSA Option", RFC 2370, July
1998.
[RFC2740] R.Coltun et al. "OSPF for IPv6", RFC 2740, December
1999.
[RFC2119] S.Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3477] K.Kompella et al. "Signalling Unnumbered Links in
Resource ReSerVation Protocol - Traffic Engineering
(RSVP-TE)", RFC 3477, January 2003.
[RFC3630] D.Katz et al. "Traffic Engineering (TE) Extensions to
OSPF Version 2", RFC 3630, September 2003.
[RFC3667] S.Bradner, "IETF Rights in Contributions", BCP 78,
RFC 3667, February 2004.
[RFC3668] S.Bradner, Ed., "Intellectual Property Rights in IETF
Technology", BCP 79, RFC 3668, February 2004.
[RFC3946] E.Mannie, and D.Papadimitriou, (Editors) et al.,
"Generalized Multi-Protocol Label Switching Extensions
for SONET and SDH Control," RFC 3946, October 2004.
[RFC4202] Kompella, K. (Editor) et al., "Routing Extensions in
Support of Generalized MPLS," RFC 4202, October 2005.
[RFC4203] Kompella, K. (Editor) et al., "OSPF Extensions in
Support of Generalized Multi-Protocol Label Switching
(GMPLS)," RFC 4203, October 2005.
8.2 Informative References
[ASON-EVAL] C.Hopps et al. "Evaluation of existing Routing Protocols
against ASON Routing Requirements", Work in progress,
draft-ietf-ccamp-gmpls-ason-routing-eval-03.txt, May
2006.
[ASON-RR] D.Brungard et al. "Requirements for Generalized MPLS
(GMPLS) Routing for Automatically Switched Optical
Network (ASON)," RFC 4258, November 2005.
[OSPF-CAP] A.Lindem et al. "Extensions to OSPF for Advertising
Optional Router Capabilities", Work in progress, draft-
ietf-ospf-cap-08.txt, November 2005.
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[OSPF-TE-CAP]J.P. Vasseur et al. , "Routing extensions for discovery
of Traffic Engineering Node Capabilities", Work in
progress, draft-ietf-ccamp-te-node-cap-01.txt, June 2006
For information on the availability of ITU Documents, please see
http://www.itu.int
[G.7715] ITU-T Rec. G.7715/Y.1306, "Architecture and
Requirements for the Automatically Switched Optical
Network (ASON)," June 2002.
[G.7715.1] ITU-T Draft Rec. G.7715.1/Y.1706.1, "ASON Routing
Architecture and Requirements for Link State Protocols,"
November 2003.
[G.8080] ITU-T Rec. G.8080/Y.1304, "Architecture for the
Automatically Switched Optical Network (ASON),"
November 2001 (and Revision, January 2003).
9. Author's Addresses
Dimitri Papadimitriou (Alcatel)
Francis Wellensplein 1,
B-2018 Antwerpen, Belgium
Phone: +32 3 2408491
EMail: dimitri.papadimitriou@alcatel.be
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Appendix 1: ASON Terminology
This document makes use of the following terms:
Administrative domain: (see Recommendation G.805) for the purposes of
[G7715.1] an administrative domain represents the extent of resources
which belong to a single player such as a network operator, a service
provider, or an end-user. Administrative domains of different players
do not overlap amongst themselves.
Control plane: performs the call control and connection control
functions. Through signaling, the control plane sets up and releases
connections, and may restore a connection in case of a failure.
(Control) Domain: represents a collection of (control) entities that
are grouped for a particular purpose. The control plane is subdivided
into domains matching administrative domains. Within an
administrative domain, further subdivisions of the control plane are
recursively applied. A routing control domain is an abstract entity
that hides the details of the RC distribution.
External NNI (E-NNI): interfaces are located between protocol
controllers between control domains.
Internal NNI (I-NNI): interfaces are located between protocol
controllers within control domains.
Link: (see Recommendation G.805) a "topological component" which
describes a fixed relationship between a "subnetwork" or "access
group" and another "subnetwork" or "access group". Links are not
limited to being provided by a single server trail.
Management plane: performs management functions for the Transport
Plane, the control plane and the system as a whole. It also provides
coordination between all the planes. The following management
functional areas are performed in the management plane: performance,
fault, configuration, accounting and security management
Management domain: (see Recommendation G.805) a management domain
defines a collection of managed objects which are grouped to meet
organizational requirements according to geography, technology,
policy or other structure, and for a number of functional areas such
as configuration, security, (FCAPS), for the purpose of providing
control in a consistent manner. Management domains can be disjoint,
contained or overlapping. As such the resources within an
administrative domain can be distributed into several possible
overlapping management domains. The same resource can therefore
belong to several management domains simultaneously, but a management
domain shall not cross the border of an administrative domain.
Subnetwork Point (SNP): The SNP is a control plane abstraction that
represents an actual or potential transport plane resource. SNPs (in
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different subnetwork partitions) may represent the same transport
resource. A one-to-one correspondence should not be assumed.
Subnetwork Point Pool (SNPP): A set of SNPs that are grouped together
for the purposes of routing.
Termination Connection Point (TCP): A TCP represents the output of a
Trail Termination function or the input to a Trail Termination Sink
function.
Transport plane: provides bi-directional or unidirectional transfer
of user information, from one location to another. It can also
provide transfer of some control and network management information.
The Transport Plane is layered; it is equivalent to the Transport
Network defined in G.805 Recommendation.
User Network Interface (UNI): interfaces are located between protocol
controllers between a user and a control domain. Note: there is no
routing function associated with a UNI reference point.
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Appendix 2: ASON Routing Terminology
This document makes use of the following terms:
Routing Area (RA): a RA represents a partition of the data plane and
its identifier is used within the control plane as the representation
of this partition. Per [G.8080] a RA is defined by a set of sub-
networks, the links that interconnect them, and the interfaces
representing the ends of the links exiting that RA. A RA may contain
smaller RAs inter-connected by links. The limit of subdivision
results in a RA that contains two sub-networks interconnected by a
single link.
Routing Database (RDB): repository for the local topology, network
topology, reachability, and other routing information that is updated
as part of the routing information exchange and may additionally
contain information that is configured. The RDB may contain routing
information for more than one Routing Area (RA).
Routing Components: ASON routing architecture functions. These
functions can be classified as protocol independent (Link Resource
Manager or LRM, Routing Controller or RC) and protocol specific
(Protocol Controller or PC).
Routing Controller (RC): handles (abstract) information needed for
routing and the routing information exchange with peering RCs by
operating on the RDB. The RC has access to a view of the RDB. The RC
is protocol independent.
Note: Since the RDB may contain routing information pertaining to
multiple RAs (and possibly to multiple layer networks), the RCs
accessing the RDB may share the routing information.
Link Resource Manager (LRM): supplies all the relevant component and
TE link information to the RC. It informs the RC about any state
changes of the link resources it controls.
Protocol Controller (PC): handles protocol specific message exchanges
according to the reference point over which the information is
exchanged (e.g. E-NNI, I-NNI), and internal exchanges with the RC.
The PC function is protocol dependent.
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