Mobile Ad hoc Networking (MANET) C. Dearlove Internet-Draft BAE Systems ATC Intended status: Standards Track July 8, 2013 Expires: January 9, 2014 Routing MPR and Other Extensions for the Optimized Link State Routing Protocol version 2 (OLSRv2) draft-dearlove-manet-olsrv2-extensions-00 Abstract This specification describes an extension to the Optimized Link State Routing Protocol version 2 (OLSRv2) to improve the selection of routing MPRs. Other considerations for extending OLSRv2 and the MANET Neighborhood Discovery Protocol (NHDP) are also given. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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Dearlove Expires January 9, 2014 [Page 1] Internet-Draft OLSRv2 Extensions July 2013 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Applicability Statement . . . . . . . . . . . . . . . . . . . 3 4. Routing MPR Selection . . . . . . . . . . . . . . . . . . . . 4 5. Unknown TLV Values . . . . . . . . . . . . . . . . . . . . . . 5 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 6.1. Address Block TLVs . . . . . . . . . . . . . . . . . . . . 6 7. Security Considerations . . . . . . . . . . . . . . . . . . . 9 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9 9.1. Normative References . . . . . . . . . . . . . . . . . . . 9 9.2. Informative References . . . . . . . . . . . . . . . . . . 10 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10 Dearlove Expires January 9, 2014 [Page 2] Internet-Draft OLSRv2 Extensions July 2013 1. Introduction The Optimized Link State Routing Protocol, version 2 [OLSRv2] is a proactive link state routing protocol designed for use in mobile ad hoc networks (MANETs) [RFC2501]. This document discusses two areas in which that specification, and in the second case also the MANET Neighborhood Discovery Protocol (NHDP) [RFC6130], can be improved. These may at some future time be divided into two separate documents. One improvement included in OLSRv2, compared to its predecessor described in [RFC3626] is the use of link metrics, rather than minimum hop routing. A rationale for how link metrics were included in OLSRv2 has been presented in [RFC6966-to-be] However, one aspect of the use of link metrics described in [RFC6966-to-be], the removal of some unnecessarily selected routing MPRs, was not included in [OLSRv2]. This specification modifies OLSRv2 to correct this oversight. Note that an implementation using this removal is not strictly compliant with [OLSRv2], but is fully compatible with implementations not using this removal. This specification defines an implementation using this removal as being compliant with the protocol OLSRv2, extending [OLSRv2]. This specification also reduces the latitude of implementations of [OLSRv2] and [RFC6130] to consider some messages, which will not be created by implementations simply following those specifications, as a reason to consider the message as ill-formed, and thus as a reason to reject the message. This gives greater latitude to the creation of extensions of these protocols, in particular extensions that will interoperate with unextended implementations of those protocols. Specifically it indicates how TLVs (Type-Length-Value elements) [RFC5444] with unexpected value fields should be handled. 2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. Additionally, this document uses the terminology of [RFC5444], [RFC6130] and [OLSRv2]. 3. Applicability Statement The two extensions described in this document are intended to modify the specification of the two protocols [OLSRv2] and (for the second Dearlove Expires January 9, 2014 [Page 3] Internet-Draft OLSRv2 Extensions July 2013 extension only) [RFC6130]. As such they are applicable to all implementations of these protocols, however the first extension is simply permissive, it allows an additional optimization, there is no necessity for any implementation to include it (although this is advised, it can, in some cases, create smaller and fewer messages and more efficient flooding, without ever having the opposite effect). [OLSRv2] defines the properties for the selection of routing MPRs (mulipoint relays) from among a router's symmetric 1-hop neighbors as properties that correspond first to that the selected MPRs consist of a set of symmetric 1-hop neighbors that cover all the symmetric 2-hop neighbors, and second that they do so retaining a minimum distance route (1-hop, if present, or 2-hop) to each symmetric 2-hop neighbor. The discussion in the latter part of Section 6.2 of [RFC6966-to-be] indicates that this requirement is over-prescriptive for routing MPR selection. This update to [OLSRv2] permits a router to use the described optimization, while still being considered compliant. (Note that, whether considered compliant or not, a router that so behaves will operate successfully, including in a network with a mixture of routers that do and do not use this optimisation.) Both [RFC6130] and [OLSRv2] define a number of TLVs that have only some values used. The second extension removes the latitude of an implementation to consider the use of such values as errors, permitting their use in extensions. Some specific usage of these cases is defined, both cases that are defined as having no function (but which can make the creation of multivalue TLVs more efficient) and the interpretation of two TLV values (MPR and NBR_ADDR_TYPE) as bit fields, which may have a minor impact on some implementations' interpretation of such fields in received messages. 4. Routing MPR Selection A set of routing MPRs created as specified in [OLSRv2] MAY be optimized in the following manner. Note that this uses the notation of Section 18.3 of [OLSRv2]: 1. If there is a sequence x_0, ..., x_n of elements of N1 such that: * x_0 is a routing MPR, * x_1, ... , x_n have corresponding elements y_1, ..., y_n of N2, and * d1(x_0) + d2(x_0,y_1) + ... + d2(x_m-1,y_m) < d1(x_m) for m = 1, ... , n, Dearlove Expires January 9, 2014 [Page 4] Internet-Draft OLSRv2 Extensions July 2013 then x_1 to x_n may be removed from the set of routing MPRs, if selected. Note that "corresponding elements" in N1 and N2 means that these elements represent the same router. All of this information is available from information gathered by NHDP ([RFC6130]). It is RECOMMENDED that all OLSRv2 routers use this optimization. 5. Unknown TLV Values NHDP [RFC6130] and OLSRv2 [OLSRv2] define a number of TLVs within the framework of [RFC5444]. A number of these TLVs specify the meaning of only some possible values that may occur in the value field of a TLV. For example the LINK_METRIC TLV defined in [RFC6130] specified a meaning only for the values 0 (LOST), 1 (symmetric) AND 2 (HEARD). These protocols also specify that, in addition to well-defined reasons, an implementation of these protoocls MAY reject a message as ill-formed for other reasons. The primary reason for that is to enable the implementation of extensions such as [NHDP-OLSRv2-sec]. It could however be interpreted as allowing rejection of a message because a TLV value is unknown. This specification removes that latitude, and states that an implementation MUST NOT reject a message because it contains such a TLV. Instead any unknown value MUST be treated, by an unextended implementation of NHSP or OLSRv2 as if the TLV were not present. (That may, in some cases, be a reason to reject the message, and that remains permitted.) Such unknown TLV values may be defined in a later specification, and thus, where appropriate, fixed specifications of values in [RFC6130] and [OLSRv2] have been re-defined in this specification as defined by extensible registries, see Section 6. An extra entry has been added to relevant registries, to represent a value that is to permanently indicate no information. The utility of this lies in considering multi-value TLVs, as defined in [RFC5444]. [RFC5444] defines a multi-value TLV that may be used to assign information, such as link status, to more than one address in an Address Block. Multi-value TLVs often represent an efficient (in terms of message size) way to convey the indicated information. However only consecutively recorded addresses may be covered by a multivalue TLV. If conveying only one or two pieces of information, it is possible to order address so as to efficiently use multivalue TLVs, but if conveying more, then this is no longer possible. In that case more than one TLV may be needed for a single type of information. With the definition of a TLV value to mean "no Dearlove Expires January 9, 2014 [Page 5] Internet-Draft OLSRv2 Extensions July 2013 information", greater use of multivalue TLs is possible, allowing both more efficient messages and simpler implementations. (An implementation must still be able to recognise whatever pattern of TLVs the sender chooses to use.) It should be stressed that this is not a change to [RFC6130] or [OLSRv2], except with regard to not allowing this to be a reason for rejection of a message. These protocols are specified in terms such as "if an address is associated with a value of LOST by a LINK_STATUS TLV". Association with an unknown value (or a value newly defined to mean no link status information) has no effect on such a specification. Specific cases that are affected are described in Section 6. In three cases (LOCAL_IF, LINK_STATUS, OTHER_NEIGHB) there is no impact on [RFC6130] or [OLSRv2]. In two cases (MPR, NBR_ADDR_TYPE) the value is now to be interpreted as a bit field. As the existing definitions of values 1, 2, and 3 behaved in that manner, it is likely that this will involve no change, but any test of (for example) Value = 1 or Value = 3 MUST be converted to a test of (for example) Value bitand 1 = 1, where "bitand" denaotes a bitwise and operation. Not reported, because unchanged, is the LINK_METRIC TLV. However it should be noted that any (two octet) value with all four most significant bits clear (0) is a case that conveys no information about the network address (and which will, at least as far as this TLV is concerned, be not used by OLSRv2). It is RECOMMENDED that when using such a value deliberately that the remaining twelve bits be either all clear (0) or all set (1). However any received pattern of bits MUST be so interpreted. 6. IANA Considerations Note: Values defined as "Unallocated: Expert Review" mean that these values may be allocated according to the expert review guidelines specified in [RFC6130] and [OLSRv2]. In two cases a constraint on how future allocation is specified. 6.1. Address Block TLVs IANA is requested to create a registry associated with the Address Block TLV with name LOCAL_IF (Type = 2, Type Extension = 0) defined in [RFC6130], specifying the meaning of its single values. This replaces the Description column in Table 6 in [RFC6130] by a reference to this table. Dearlove Expires January 9, 2014 [Page 6] Internet-Draft OLSRv2 Extensions July 2013 +---------+-------------+-------------------------------------------+ | Value | Name | Description | +---------+-------------+-------------------------------------------+ | 0 | THIS_IF | The network address is associated with | | | | this local interface of the sending | | | | router | | 1 | OTHER_IF | The network address is associated with | | | | another local interface of the sending | | | | router | | 2-223 | | Unallocated: Expert Review | | 224-254 | | Experimental Use | | 255 | UNSPECIFIED | No information about this network address | | | | is provided | +---------+-------------+-------------------------------------------+ Table 1: LOCAL_IF TLV Values IANA are reqested to create a registry associated with the Address Block TLV with name LINK_STATUS (Type = 3, Type Extension = 0) defined in [RFC6130], specifying the meaning of its single values. This replaces the Description column in Table 7 in [RFC6130] by a reference to this table. +---------+-------------+-------------------------------------------+ | Value | Name | Description | +---------+-------------+-------------------------------------------+ | 0 | LOST | The link on this interface from the | | | | router with that network address has been | | | | lost | | 1 | SYMMETRIC | The link on this interface from the | | | | router with that network address has the | | | | status of symmetric | | 2 | HEARD | The link on this interface from the | | | | router with that network address has the | | | | status of heard | | 3-223 | | Unallocated: Expert Review | | 224-254 | | Experimental Use | | 255 | UNSPECIFIED | No information about this network address | | | | is provided | +---------+-------------+-------------------------------------------+ Table 2: LINK_STATUS TLV Values IANA are reqested to create a registry associated with the Address Block TLV with name OTHER_NEIGHB (Type = 4, Type Extension = 0) defined in [RFC6130], specifying the meaning of its single values. This replaces the Description column in Table 8 in [RFC6130] by a reference to this table. Dearlove Expires January 9, 2014 [Page 7] Internet-Draft OLSRv2 Extensions July 2013 +---------+-------------+-------------------------------------------+ | Value | Name | Description | +---------+-------------+-------------------------------------------+ | 0 | LOST | The neighbour relationship with the | | | | router with that network address has been | | | | lost | | 1 | SYMMETRIC | The neighbour relationship with the | | | | router with that network address is | | | | symmetric | | 2-223 | | Unallocated: Expert Review | | 224-254 | | Experimental Use | | 255 | UNSPECIFIED | No information about this network address | | | | is provided | +---------+-------------+-------------------------------------------+ Table 3: OTHER_NEIGHB TLV Values IANA are reqested to create a registry associated with the Address Block TLV with name MPR (Type = 8, Type Extension = 0) defined in [OLSRv2], specifying the meaning of its single values in terms of the values of each bit of the value, from bit 0 (most significant) to bit 7 (least significant). If multiple bits are set then each applies. This replaces the Description column in Table 14 in [OLSRv2] by a reference to this table. +-------+-------+----------+----------------------------------------+ | Value | Value | Name | Description | | Bit | | | | +-------+-------+----------+----------------------------------------+ | 7 | 1 | FLOODING | The neighbour with that network | | | | | address has been selected as flooding | | | | | MPR | | 6 | 2 | ROUTING | The neighbour with that network | | | | | address has been selected as flooding | | | | | MPR | | 0-5 | | | Unallocated: Expert Review | +-------+-------+----------+----------------------------------------+ Table 4: MPR TLV Bit Values The combination FLOODING + ROUTING (Value = 3) is given the name FLOOD_ROUTE in [OLSRv2]. All future allocated bits MUST use the unset bit (0) to indicates no information, so that the case Value = 0 will always indicate that no information about this network address is provided. IANA are reqested to create a registry associated with the Address Block TLV with name NBR_ADDR_TYPE (Type = 9, Type Extension = 0) Dearlove Expires January 9, 2014 [Page 8] Internet-Draft OLSRv2 Extensions July 2013 defined in [OLSRv2], specifying the meaning of its single values in terms of the values of each bit of the value, from bit 0 (most significant) to bit 7 (least significant). If multiple bits are set then each applies. This replaces the Description column in Table 15 in [OLSRv2] by a reference to this table. +-------+-------+------------+--------------------------------------+ | Value | Value | Name | Description | | Bit | | | | +-------+-------+------------+--------------------------------------+ | 7 | 1 | ORIGINATOR | The network address is an originator | | | | | address reachable via the | | | | | originating router | | 6 | 2 | ROUTABLE | The network address is a routable | | | | | address reachable via the | | | | | originating router | | 0-5 | | | Unallocated: Expert Review | +-------+-------+------------+--------------------------------------+ Table 5: NBR_ADDR_TYPE TLV Bit Values The combination ORIGINATOR + ROUTABLE (Value = 3) is given the name ROUTABLE_ORIG in [OLSRv2]. All future allocated bits MUST use the unset bit (0) to indicates no information, so that the case Value = 0 will always indicate that no information about this network address is provided. 7. Security Considerations TBD. 8. Acknowledgments TBD. 9. References 9.1. Normative References [OLSRv2] Clausen, T., Dearlove, C., Jacquet, P., and U. Herberg, "The Optimized Link State Routing Protocol version 2", work in progress draft-ietf-manet-olsrv2-19, March 2013. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. Dearlove Expires January 9, 2014 [Page 9] Internet-Draft OLSRv2 Extensions July 2013 [RFC5444] Clausen, T., Dearlove, C., Dean, J., and C. Adjih, "Generalized MANET Packet/Message Format", RFC 5444, February 2009. [RFC6130] Clausen, T., Dean, J., and C. Dearlove, "Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)", RFC 6130, April 2011. 9.2. Informative References [NHDP-OLSRv2-sec] Herberg, U., Dearlove, C., and T. Clausen, "Integrity Protection for Control Messages in NHDP and OLSRv2", work in progress draft-ietf-manet-nhdp-olsrv2-sec-03, July 2013. [RFC2501] Macker, J. and S. Corson, "Mobile Ad hoc Networking (MANET): Routing Protocol Performance Issues and Evaluation Considerations", RFC 2501, January 1999. [RFC3626] Clausen, T. and P. Jacquet, "The Optimized Link State Routing Protocol", RFC 3626, October 2003. [RFC6966-to-be] Clausen, T., Dearlove, C., and P. Jacquet, "Rationale for the Use of Link Metrics in the Optimized Link State Routing Protocol Version 2 (OLSRv2)", RFC 6966, TBD 2013. Author's Address Christopher Dearlove BAE Systems Advanced Technology Centre West Hanningfield Road Great Baddow, Chelmsford United Kingdom Phone: +44 1245 242194 Email: chris.dearlove@baesystems.com URI: http://www.baesystems.com/ Dearlove Expires January 9, 2014 [Page 10]