OSPF WG S. Venkata Internet-Draft Google Inc. Intended status: Standards Track S. Harwani Expires: July 29, 2008 C. Pignataro Cisco Systems D. McPherson Arbor Networks, Inc. January 26, 2008 Dynamic Hostname Exchange Mechanism for OSPF draft-venkata-ospf-dynamic-hostname-02 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. This Internet-Draft will expire on July 29, 2008. Copyright Notice Copyright (C) The IETF Trust (2008). Abstract Currently, there does not exist a simple and dynamic mechanism for routers running OSPF to learn about symbolic hostnames just like for routers running IS-IS. This document defines a new OSPF Router Information (RI) TLV which allows the OSPF routers to flood their Venkata, et al. Expires July 29, 2008 [Page 1] Internet-Draft Dynamic Hostnames for OSPF January 2008 hostname-to-Router ID mapping information across the OSPF network. This mechanism is applicable to both OSPFv2 and OSPFv3. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Specification of Requirements . . . . . . . . . . . . . . . 3 2. Possible solutions . . . . . . . . . . . . . . . . . . . . . . 3 3. Implementation . . . . . . . . . . . . . . . . . . . . . . . . 4 3.1. Dynamic Hostname TLV . . . . . . . . . . . . . . . . . . . 4 4. IPv6 Considerations . . . . . . . . . . . . . . . . . . . . . . 5 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 6 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 8.1. Normative References . . . . . . . . . . . . . . . . . . . 6 8.2. Informative References . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 Intellectual Property and Copyright Statements . . . . . . . . . . 8 Venkata, et al. Expires July 29, 2008 [Page 2] Internet-Draft Dynamic Hostnames for OSPF January 2008 1. Introduction OSPF uses a 32-bit Router ID to uniquely represent and identify a node in the network. For management and operational reasons, network operators need to check the status of OSPF adjacencies, entries in the routing table and the content of the OSPF link state database. It is obvious that, when looking at diagnostic information, numerical representations of Router IDs (e.g., dotted-decimal or hexadecimal representations) are less clear to humans than symbolic names. One way to overcome this problem is to define a hostname-to-Router ID mapping table on a router. This mapping can be used bidirectionally (e.g., to find symbolic names for Router IDs, and to find Router IDs for symbolic names) or unidirectionally (e.g., to find symbolic hostnames for Router IDs). Thus every router has to maintain a table with mappings between router names and Router IDs. These tables need to contain all names and Router IDs of all routers in the network. If these mapping tables are built by static definitions, it can become a manual and tedious process in operational networks currently; modifying these static mapping entries when additions, deletions or changes occur becomes a non- scalable process very prone to error. This document analyzes possible solutions to this problem (see Section 2) and provides a way to populate tables by defining a new OSPF Router Information TLV for OSPF, the Dynamic Hostname TLV (see Section 3). This mechanism is applicable to both OSPFv2 and OSPFv3. 1.1. Specification of Requirements 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 [RFC2119]. 2. Possible solutions There are various approaches to providing a name-to-Router ID mapping service. One way to build this table of mappings is by static definitions. The problem with static definitions is that the network administrator needs to keep updating the mapping entries manually as the network changes; this approach does not scale as the network grows, since there needs to be an entry in the mapping table for each and every router in the network, on every router in the network. Thus, this approach greatly suffers from maintainability and scalability Venkata, et al. Expires July 29, 2008 [Page 3] Internet-Draft Dynamic Hostnames for OSPF January 2008 considerations. Another approach is having a centralized location where the name-to- Router ID mapping can be kept. DNS can be used for the same. A disadvantage with this centralized solution is that its a single point of failure; and although enhanced availability of the central mapping service can be designed, it may not be able to resolve the hostname in the event of reachability or network problems. Also, the response time can be an issue with the centralized solution, which can be particularly problematic in times of problem resolution. If DNS is used as the centralized mapping table, a network operator may desire a different name mapping than the existing in the DNS, or new routers may not yet be in DNS. Additionally for OSPFv3, in native IPv6 deployments, the 32-bit Router ID value will not map to IPv4-addressed entities in the network, nor will it be DNS resolvable (see Section 4). The third solution that we have defined in this document is to make use of the protocol itself to carry the name-to-Router ID mapping in a TLV. Routers that understand this TLV can use it to create the symbolic name-to-Router ID mapping and Routers who don't understand can simply ignore it. This specification provides these semantics and mapping mechanisms for OSPFv2 and OSPFv3, leveraging the OSPF Router Information (RI) LSA ([RFC4970]). 3. Implementation This extension makes use of the Router Information (RI) Opaque LSA defined in [RFC4970] for both OSPFv2 and OSPFv3, by defining a new OSPF Router Information (RI) TLV: The Dynamic Hostname TLV. The Dynamic Hostname TLV (see Section 3.1) is OPTIONAL. Upon receipt of the TLV a router may decide to ignore this TLV, or to install the symbolic name and Router ID in its hostname mapping table. 3.1. Dynamic Hostname TLV The format of Dynamic Hostname TLV is 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Hostname ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Venkata, et al. Expires July 29, 2008 [Page 4] Internet-Draft Dynamic Hostnames for OSPF January 2008 Type Dynamic Hostname TLV Type (TBD, see Section 6) Length Total length of the hostname (value field) in octets, not including the optional padding. Value Hostname, a string of 1 to 255 octets, padded to 4-octet alignment. Routers that do not recognize the Dynamic Hostname TLV Type, ignore the TLV (see [RFC4970]). The value field identifies the symbolic hostname of the router originating the LSA. The string is not null-terminated. The Router ID of this router is derived from the LSA header, in the Advertising Router field of the Router Information (RI) Opaque LSA. The Dynamic Hostname TLV is applicable to both OSPFv2 and OSPFv3. The Dynamic Hostname TLV MAY be advertised within an area-local or AS scope Router Information LSA. The flooding scope is controlled by the Opaque LSA type in OSPFv2 and by the S1 and S2 bits in OSPFv3. For area scope, the Dynamic Hostname TLV MUST be carried within an OSPFv2 Type 10 RI LSA or an OSPFv3 RI LSA with the S1 bit set and S2 bit clear. If the flooding scope is the entire routing domain (AS scope), the Dynamic Hostname TLV MUST be carried within an OSPFv2 Type 11 RI LSA or OSPFv3 RI LSA with the S1 bit clear and the S2 bit set. An AS boundary router (ASBR) may choose to send an AS scope Dynamic Hostname TLV, whereas area boundary router (ABRs) and internal routers may choose to send an area scope Dynamic Hostname TLV. If a router originates Dynamic Hostname TLVs with an IGP domain (AS) flooding scope, it MAY omit sending area-scoped Dynamic Hostname TLVs. 4. IPv6 Considerations Both OSPFv2 and OSPFv3 employ Router IDs with a common size of 32- bits. In IPv4 the Router ID values were typically derived automatically from an IPv4 address configured on a loopback or physical interface defined on the local system, or explicitly defined within the OSPF process configuration. With broader deployment of IPv6, it's quite likely that OSPF networks will exist that have no native IPv4 addressed interfaces. As a result, a 32-bit OSPF Router ID will either need to be explicitly specified, or derived in some automatic manner that avoids collisions with other OSPF routers within the local routing domain. Because this 32-bit value will not map to IPv4-addressed entities in Venkata, et al. Expires July 29, 2008 [Page 5] Internet-Draft Dynamic Hostnames for OSPF January 2008 the network, nor will it be DNS resolvable, it is considered extremely desirable from an operational perspective that some mechanism exist to map OSPF Router IDs to more easily interpreted values, ideally, human-readable strings. This specification enables a mapping functionality which eases operational burdens that may otherwise be introduced with native deployment of IPv6. 5. Security Considerations This document raises no new security issues for OSPF. Security considerations for the base OSPF protocol are covered in [RFC2328] and [RFC2740]. The use of authentication for the OSPF routing protocols is encouraged. 6. IANA Considerations IANA maintains the "OSPF Router Information (RI) TLVs" registry reachable at [IANA-RI]. An additional OSPF Router Information TLV Type is defined in Section 3. It is required to be assigned by IANA from the Standards Action allocation range [RFC4970]. Registry Name: OSPF Router Information (RI) TLVs Type Value Capabilities Reference ----------- -------------------------------------- --------- TBD OSPF Dynamic Hostname This document 7. Acknowledgments The authors of this document do not make any claims on the originality of the ideas described. This document adapts format and text from similar work done in IS-IS [RFC2763]; we would like to thank Naiming Shen and and Henk Smit, authors of that document. The authors would also like to thank Acee Lindam and Abhay Roy for their valuable comments. 8. References 8.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. Venkata, et al. Expires July 29, 2008 [Page 6] Internet-Draft Dynamic Hostnames for OSPF January 2008 [RFC4970] Lindem, A., Shen, N., Vasseur, JP., Aggarwal, R., and S. Shaffer, "Extensions to OSPF for Advertising Optional Router Capabilities", RFC 4970, July 2007. 8.2. Informative References [IANA-RI] Internet Assigned Numbers Authority, "OSPFv2 Parameters", January 2008, . [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998. [RFC2740] Coltun, R., Ferguson, D., and J. Moy, "OSPF for IPv6", RFC 2740, December 1999. [RFC2763] Shen, N. and H. Smit, "Dynamic Hostname Exchange Mechanism for IS-IS", RFC 2763, February 2000. Authors' Addresses Subbaiah Venkata Google Inc. Email: svenkata@google.com URI: http://www.google.com Sanjay Harwani Cisco Systems Email: sharwani@cisco.com URI: http://www.cisco.com Carlos Pignataro Cisco Systems Email: cpignata@cisco.com URI: http://www.cisco.com Danny McPherson Arbor Networks, Inc. Email: danny@arbor.net Venkata, et al. Expires July 29, 2008 [Page 7] Internet-Draft Dynamic Hostnames for OSPF January 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). 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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Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Venkata, et al. Expires July 29, 2008 [Page 8]