CCAMP Working Group Dimitri Papadimitriou Internet Draft (Alcatel) Category: Standard Expiration Date: August 2006 March 2006 Link State Routing Protocols Extensions for ASON Routing draft-dimitri-ccamp-gmpls-ason-routing-sol-01.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Copyright Notice Copyright (C) The Internet Society (2006). All Rights Reserved. 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 IETF Link State Routing Protocols to meet the routing requirements for an Automatically Switched Optical Network (ASON) as defined by ITU-T. D.Papadimitriou et al. - Expires August 2006 1 draft-dimitri-ccamp-gmpls-ason-routing-sol-01.txt February 2006 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). ASON (Routing) terminology sections are provided in Appendix 1 and 2. 3. Reachability 3.1 OSPFv2 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 OSPF 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 3.1.1 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: D.Papadimitriou et al. - Expires August 2006 2 draft-dimitri-ccamp-gmpls-ason-routing-sol-01.txt February 2006 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 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. 3.1.2 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 | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . . . . . . D.Papadimitriou et al. - Expires August 2006 3 draft-dimitri-ccamp-gmpls-ason-routing-sol-01.txt February 2006 . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 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. 3.2 IS-IS A similar mechanism does not exist for IS-IS as the Extended IP Reachability TLV [RFC3784] focuses on IP reachable end-points (terminating points), as its name indicates. For this purpose, a new Extended TE Reachability TLV (Type TBD) is defined as follows 7 octets of system Id and pseudonode number 1 octet of length of sub-TLVs 0-246 octets of sub-TLVs, where each sub-TLV consists of a sequence of 1 octet of sub-type 1 octet of length of the value field of the sub-TLV 0-244 octets of value Each sub-TLV (Type TBD) is either an IPv4 TE Reachability sub-TLV or an IPv6 TE Reachability sub-TLV. 3.2.1 IPv4 TE Reachability sub-TLV The "IPv4 TE Reachability" sub-TLV describes TE reachability through the specification of a routing prefix, a bit to indicate if the prefix is being advertised down from a higher level, and optionally the existence of sub-TLVs to allow for later extension. The following illustrates encoding of the Value field of this sub-TLV D.Papadimitriou et al. - Expires August 2006 4 draft-dimitri-ccamp-gmpls-ason-routing-sol-01.txt February 2006 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |U| Reserved | Prefix Len| Prefix | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Prefix | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The 6 bits of prefix length can have the values 0-32 and indicate the number of significant bits in the prefix. The prefix is encoded in the minimal number of octets for the given number of significant bits. The remaining bits of prefix are transmitted as zero and ignored upon receipt. The U bit is described in Section 6.2. 3.2.2 IPv6 TE Reachability sub-TLV The "IPv6 TE Reachability" sub-TLV describes TE reachability through the specification of a routing prefix, a bit to indicate if the prefix is being advertised down from a higher level, and optionally the existence of sub-TLVs to allow for later extension. The following illustrates encoding of the Value field of this sub-TLV 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |U| Reserved | Prefix Len | Prefix | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ Prefix ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Prefix ... | +-+-+-+-+-+-+-+-+ The 8 bits of prefix length can have the values 0-128 and indicate the number of significant bits in the prefix. Only the required number of octets of prefix are present. This number can be computed from the prefix length octet as follows: prefix octets = integer of ((prefix length + 7) / 8) The U bit is described in Section 6.2. 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. D.Papadimitriou et al. - Expires August 2006 5 draft-dimitri-ccamp-gmpls-ason-routing-sol-01.txt February 2006 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. 4.1.2 OSPFv2 In OSPFv2, the Interface Switching Capability Descriptor is a sub- TLV (of type TBA) of the 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. 4.1.2 IS-IS In IS-IS, the Interface Adaptation Capability Descriptor is a sub- TLV (of type TBA) of the Extended IS Reachability TLV (of type 22) [RFC4205]. The adaptation and termination capabilities are advertised using two separate ISCD sub-TLVs within the same Extended IS Reachability 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 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]. D.Papadimitriou et al. - Expires August 2006 6 draft-dimitri-ccamp-gmpls-ason-routing-sol-01.txt February 2006 The purpose is purely informative: there is no mandatory processing or topology/traffic-engineering significance associated to this information. 4.2.1 OSPFv2 In OSPF, the Interface Switching Capability Descriptor is a sub-TLV (of type 15) of the Link TLV (of type 2). 4.2.2 IS-IS In IS-IS, the Interface Switching Capability Descriptor is a sub-TLV (of type 21) of the Extended IS Reachability TLV (of type 22). 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. 5.1.1 OSPFv2 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. 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 D.Papadimitriou et al. - Expires August 2006 7 draft-dimitri-ccamp-gmpls-ason-routing-sol-01.txt February 2006 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 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. 5.1.2 IS-IS For this purpose, a new sub-TLV of the Extended IS Reachability TLV (Type 22, RFC 3784) is introduced that defines the local and the remote TE_Router_ID. The type of this sub-TLV is TBD, 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 the value field 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Local TE Router Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Remote TE Router Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ This sub-TLV is optional and SHOULD only be included as part of the Extended IS Reachability TLV if the RC is advertising on behalf of more than one TE_Router_ID. In any other case, this sub-TLV SHOULD be omitted. 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. 5.2.1 OSPFv2 D.Papadimitriou et al. - Expires August 2006 8 draft-dimitri-ccamp-gmpls-ason-routing-sol-01.txt February 2006 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 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. 5.2.2 IS-IS For this purpose, a new sub-TLV of the newly defined Extended TE Reachability TLV is introduced that defines the local TE_Router_ID. The type of this sub-TLV is TBD, and length is four octets. The value field of this sub-TLV contains four octets of Local TE Router Identifier [RFC3784]. The format of the value field 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Local TE Router Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ This sub-TLV is optional and SHOULD only be included as part of the Extended TE Reachability TLV if the RC 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 6.1 OSPFv2 RC disseminates downward/upward the hierarchy by re-originating this routing information as Opaque TE LSA (Opaque Type 1) of LS Type 10. D.Papadimitriou et al. - Expires August 2006 9 draft-dimitri-ccamp-gmpls-ason-routing-sol-01.txt February 2006 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 than 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 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 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 than one RC are bound to adjacent levels and both 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 3.1) and upon strict policy control link topology information. 6.1.1 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-TE-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 supporting RCs, the RC with the highest Router ID SHOULD be selected. More precisely, 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. It is expected that other RCs will 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 MaxAge. Note that alternatively if this information cannot be discovered automatically, it MUST be manually configured. The same mechanism is used for selecting the RC taking in charge dissemination of routing information downward the hierarchy with the restriction that the RC selection process needs to take into account that an upper level may be adjacent to one or more lower levels. For D.Papadimitriou et al. - Expires August 2006 10 draft-dimitri-ccamp-gmpls-ason-routing-sol-01.txt February 2006 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-TE-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 SHOULD be selected. More precisely, the RC with the highest Router ID among the RCs having set the D bit SHOULD be selected as the RC for downward dissemination of routing information. It is expected that other RCs for the same Associated Area ID will 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. Note that alternatively if this information cannot be discovered automatically, it MUST be manually configured. 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. 6.1.2 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 D.Papadimitriou et al. - Expires August 2006 11 draft-dimitri-ccamp-gmpls-ason-routing-sol-01.txt February 2006 looping/re-introduction of routing information back to the upper level. In all other cases, the procedure described in this section is optional. 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. Thus we need some way of filtering the downward/onward re-originated Opaque TE LSA. For opaque LSAs including the Router Address TLV, if the Router address has been already installed into the TEDB, the LSA should not be re-originated since this address belongs to a router part of the target area. For opaque LSAs including the Link TLV, if the Link ID has been already installed into the TEDB, the LSA should not be re-originated since the corresponding router ID belongs to a router part of the target area. For opaque LSAs including the Node Attribute TLV, if one of the included prefixes has been already installed into the TEDB, the LSA should not be re-originated with that prefix since the corresponding reachable end-points belonging to a router part of the target area. If no prefix remains, the LSA SHOULD not be re-originated. 6.2. IS-IS 6.2.1 Discovery and Selection In order to discover RCs that are capable to disseminate routing information upward the routing hierarchy, the following Capability Descriptor bit [ISIS-TE-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 supporting RCs, the RC with the highest Router ID [ISIS-CAP] SHOULD be selected. More precisely, 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. It is expected that other RCs will not participate in the upward dissemination of routing information as long as the routing information corresponding to the highest Router ID RC is not withdrawn. Note that alternatively if this information cannot be discovered automatically, it MUST be manually configured. D.Papadimitriou et al. - Expires August 2006 12 draft-dimitri-ccamp-gmpls-ason-routing-sol-01.txt February 2006 The same mechanism is used for selecting the RC taking in charge dissemination of routing information downward the hierarchy with the restriction that the RC selection process needs to take into account that an upper level may be adjacent to one or more lower levels. For this purpose a specific TLV indexing the (lower) ISIS area ID to which the RC's are capable to disseminate routing information is needed. To discover RCs that are capable to disseminate routing information downward the routing hierarchy, the following Capability Descriptor bit [ISIS-TE-CAP] is defined: - 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 ISIS Area ID, the RC with the highest Router ID SHOULD be selected. More precisely, the RC with the highest Router ID among the RCs having set the D bit SHOULD be selected as the RC for downward dissemination of routing information. It is expected that other RCs for the same Area ID will not participate in the downward dissemination of routing information as long as the routing information corresponding to the highest Router ID RC is not withdrawn. Note that alternatively if this information cannot be discovered automatically, it MUST be manually configured. The ISIS Router Capability TLV [ISIS-CAP] and its content in particular MUST NOT be redistributed between adjacent levels. 6.2.2 Loop prevention As described in [RFC3784], to prevent this looping of TE reachable prefixes between levels, an up/down bit (U bit) is defined in the newly defined extended TE reachability TLV. The up/down bit MUST be set to 0 when a prefix is first injected into IS-IS. If a prefix is advertised from a higher level to a lower level (e.g. level 2 to level 1), the bit MUST be set to 1, indicating that the prefix has traveled down the hierarchy. Prefixes that have the up/down bit set to 1 may only be advertised down the hierarchy, i.e. to lower levels. For the extended IS reachability TLV, the same re-origination rules as described in Section 6.1.2 applies. 7. OSPFv2 Extensions 7.1 Compatibility Extensions specified in this document are associated to the D.Papadimitriou et al. - Expires August 2006 13 draft-dimitri-ccamp-gmpls-ason-routing-sol-01.txt February 2006 OSPFv2 TE LSA: o) Router Address top level TLV (Type 1): - no additional sub-TLV 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 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 OSPFv2 RI LSA: o) Routing information dissemination - U and D bit in Capability Descriptor TLV [OSPF-TE-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. IS-IS Extensions and Compatibility TBD 9. Acknowledgements The authors would like to thank Alan Davey and Adrian Farrel for their useful comments and suggestions. 10. References 11.1 Normative References D.Papadimitriou et al. - Expires August 2006 14 draft-dimitri-ccamp-gmpls-ason-routing-sol-01.txt February 2006 [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. [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. [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. [RFC3784] H.Smit and T.Li, "Intermediate System to Intermediate System (IS-IS) Extensions for Traffic Engineering (TE)," RFC 3784, June 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. 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-02.txt, October 2005. [ASON-RR] D.Brungard et al. "Requirements for Generalized MPLS (GMPLS) Routing for Automatically Switched Optical Network (ASON)," RFC 4258, November 2005. For information on the availability of ITU Documents, please see D.Papadimitriou et al. - Expires August 2006 15 draft-dimitri-ccamp-gmpls-ason-routing-sol-01.txt February 2006 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 D.Papadimitriou et al. - Expires August 2006 16 draft-dimitri-ccamp-gmpls-ason-routing-sol-01.txt February 2006 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 D.Papadimitriou et al. - Expires August 2006 17 draft-dimitri-ccamp-gmpls-ason-routing-sol-01.txt February 2006 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. D.Papadimitriou et al. - Expires August 2006 18 draft-dimitri-ccamp-gmpls-ason-routing-sol-01.txt February 2006 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. D.Papadimitriou et al. - Expires August 2006 19 draft-dimitri-ccamp-gmpls-ason-routing-sol-01.txt February 2006 Full Copyright Statement Copyright (C) The Internet Society (2005). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. 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