Internet DRAFT - draft-dimitri-ccamp-gmpls-ason-routing-ospf

draft-dimitri-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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