OSPF Working Group X. Xu, Ed.
Internet-Draft Huawei
Intended status: Standards Track B. Decraene, Ed.
Expires: January 4, 2018 Orange
R. Raszuk
Bloomberg LP
L. Contreras
Telefonica I+D
L. Jalil
Verizon
July 3, 2017
Advertising Tunneling Capability in OSPF
draft-ietf-ospf-encapsulation-cap-05
Abstract
Networks use tunnels for a variety of reasons. A large variety of
tunnel types are defined and the ingress needs to select a type of
tunnel which is supported by the egress and itself. This document
defines how to advertise egress tunnel capabilities in OSPF Router
Information Link State Advertisement (LSAs).
Requirements Language
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].
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/.
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."
This Internet-Draft will expire on January 4, 2018.
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Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Advertising Encapsulation Capability . . . . . . . . . . . . 3
4. Tunnel Encapsulation Type . . . . . . . . . . . . . . . . . . 4
5. Tunnel Encapsulation Attribute . . . . . . . . . . . . . . . 4
6. Tunnel Encapsulation Attribute Sub-TLVs . . . . . . . . . . . 5
6.1. Encapsulation Sub-TLV . . . . . . . . . . . . . . . . . . 5
6.2. Protocol Type Sub-TLV . . . . . . . . . . . . . . . . . . 5
6.3. Endpoint Sub-TLV . . . . . . . . . . . . . . . . . . . . 5
6.4. Color Sub-TLV . . . . . . . . . . . . . . . . . . . . . . 5
6.5. IP QoS Field . . . . . . . . . . . . . . . . . . . . . . 6
6.6. UDP Destination Port . . . . . . . . . . . . . . . . . . 6
6.7. future sub-TLV allocations . . . . . . . . . . . . . . . 6
7. Usage of the Tunnel Encapsulation attribute . . . . . . . . . 6
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
8.1. OSPF Router Information . . . . . . . . . . . . . . . . . 7
8.2. IGP Tunnel Encapsulation Attribute Sub-TLVs Registry . . 7
9. Security Considerations . . . . . . . . . . . . . . . . . . . 7
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 8
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
12.1. Normative References . . . . . . . . . . . . . . . . . . 8
12.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
Networks use tunnels for a variety of reasons, such as:
o Partial deployment of MPLS-SPRING as described in
[I-D.xu-mpls-unified-source-routing-instruction], where IP tunnels
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are used between MPLS-SPRING-enabled routers to traverse non-MPLS
routers.
o Partial deployment of MPLS-BIER as described in
[I-D.ietf-bier-architecture], where IP tunnels are used between
MPLS-BIER-capable routers to traverse non MPLS-BIER
[I-D.ietf-bier-mpls-encapsulation] routers.
o Partial deployment of IPv6 in IPv4 networks or IPv4 in IPv6
networks as described in [RFC5565], where IPvx tunnels are used
between IPvx-enabled routers so as to traverse non-IPvx routers.
o Remote Loop-Free Alternate (RLFA) repair tunnels as described in
[RFC7490], where tunnels are used between the Point of Local
Repair and the selected PQ node.
The ingress needs to select a type of tunnel which is supported by
the egress and itself. This document describes how to use OSPF
Router Information Link State Advertisements (LSAs) to advertise the
egress tunneling capabilities of OSPF routers. In this document,
OSPF refers to both OSPFv2 [RFC2328] and OSPFv3 [RFC5340].
2. Terminology
This memo makes use of the terms defined in [RFC7770].
3. Advertising Encapsulation Capability
Routers advertise their supported encapsulation type(s) by
advertising a new TLV of the OSPF Router Information (RI) Opaque LSA
[RFC7770], referred to as the Encapsulation Capability TLV. This TLV
is applicable to both OSPFv2 and OSPFv3. The Encapsulation
Capability TLV SHOULD NOT appear more than once within a given OSPF
Router Information (RI) Opaque LSA. If the Encapsulation Capability
TLV appears more than once in an OSPF Router Information LSA, only
the first occurrence MUST be processed and others MUST be ignored.
The scope of the advertisement depends on the application but it is
recommended that it SHOULD be domain- wide. The Type code of the
Encapsulation Capability TLV is TBD1, the Length value is variable,
and the Value field contains one or more Tunnel Encapsulation Type
Sub-TLVs. Each Encapsulation Type Sub-TLVs indicates a particular
encapsulation format that the advertising router supports along with
the parameters to be used for the tunnel.
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4. Tunnel Encapsulation Type
The Tunnel Encapsulation Type Sub-TLV is structured 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tunnel Type (2 Octets) | Length (2 Octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Sub-TLVs |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Tunnel Type (2 octets): Identifies the type of tunneling
technology being signaled. Tunnel types are shared with the BGP
extension [RFC5512] and hence are defined in the IANA registry
"BGP Tunnel Encapsulation Attribute Tunnel Types". Unknown types
are to be ignored and skipped upon receipt.
Length (2 octets): Unsigned 16-bit integer indicating the total
number of octets of the value field.
Value (variable): Zero or more Tunnel Encapsulation Attribute Sub-
TLVs as defined in Section 5.
5. Tunnel Encapsulation Attribute
The Tunnel Encapsulation Attribute Sub-TLV is structured as follows:
+-----------------------------------+
| Sub-TLV Type (1 Octet) |
+-----------------------------------+
| Sub-TLV Length (1 Octet) |
+-----------------------------------+
| Sub-TLV Value (Variable) |
| |
+-----------------------------------+
Sub-TLV Type (1 octet): Each Sub-TLV type defines a certain
property of the tunnel TLV that contains this Sub-TLV. This
document defines such types Section 6 )
Sub-TLV Length (1 octet): Unsigned 8-bit integer indicating the
total number of octets of the Sub-TLV value field.
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Sub-TLV Value (variable): Encodings of the value field depend on
the Sub-TLV type as enumerated above. The following sub-sections
define the encoding in detail.
Any unknown Sub-TLVs MUST be ignored and skipped upon receipt.
However, if the TLV is understood, the entire TLV MUST NOT be ignored
just because it contains an unknown Sub-TLV.
If a Sub-TLV is invalid, this specific Tunnel Encapsulation MUST be
ignored and skipped. However, other Tunnel Encapsulations MUST be
considered.
6. Tunnel Encapsulation Attribute Sub-TLVs
6.1. Encapsulation Sub-TLV
This Sub-TLV is defined in section 3.2 "Encapsulation Sub-TLVs for
Particular Tunnel Types" of [I-D.ietf-idr-tunnel-encaps] from both a
syntax and semantic standpoint. Usage is defined in Section 7.
6.2. Protocol Type Sub-TLV
This Sub-TLV is defined in section 3.4.1 "Protocol Type sub-TLV" of
[I-D.ietf-idr-tunnel-encaps] from a syntactic, semantic, and usage
standpoint.
6.3. Endpoint Sub-TLV
The value field carries the Network Address to be used as tunnel
destination address.
If length is 4, the tunnel endpoint is an IPv4 address.
If length is 16, the tunnel endpoint is an IPv6 address.
6.4. Color Sub-TLV
The valued field is a 4-octet opaque unsigned integer.
The color value is user-defined and configured locally on the
advertising routers. It may be used by service providers to define
policies on the ingress routers, for example, to control the
selection of the tunnel to use.
This color value can be referenced by BGP routes carrying Color
Extended Community [I-D.ietf-idr-tunnel-encaps]. If the tunnel is
used to reach the BGP Next-Hop of BGP routes, then attaching a Color
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Extended Community attached to those routes express the willingness
of the BGP speaker to use a tunnel of the same color.
6.5. IP QoS Field
This Sub-TLV is defined in section 3.3.1 "IPv4 DS Field" of
[I-D.ietf-idr-tunnel-encaps] from a syntactic, semantic and usage
standpoint.
6.6. UDP Destination Port
This Sub-TLV is defined in section 3.3.2 "UDP Destination Port" of
[I-D.ietf-idr-tunnel-encaps] from a syntactic, semantic and usage
standpoint.
6.7. future sub-TLV allocations
[I-D.ietf-idr-tunnel-encaps] similarly defines Tunnel Encapsulation
Attribute Sub-TLVs. IGP and BGP have separate IANA registries
allowing for separate sub-TLV definitions. If the same information
is to be advertised for both IGP and BGP tunnel encapsulation, it is
RECOMMENDED to use the same code point, semantic and syntax.
However, it is to be noted that the "BGP Tunnel Encapsulation
Attribute Sub-TLVs" registry, allows for sub-TLV with two octets of
length, while the "IGP Tunnel Encapsulation Attribute Sub-TLVs"
registry only allows for one octet of length. Hence two-octets BGP
Tunnel Encapsulation Attribute Sub-TLVs won't be able to be defined
for IGP Tunnels. Eventually, their information may be split over
multiple sub-TLVs.
7. Usage of the Tunnel Encapsulation attribute
The advertisement of an Encapsulation Type Sub-TLVs indicates that
the advertising router support a particular tunnel encapsulation
along with the parameters to be used for the tunnel. The decision to
use that tunnel is driven by the capability of the ingress router to
support the encapsulation type and the policy on the ingress router.
The color sub-TLV may be used as an input to this policy. Note that
some tunnel types may require the execution of an explicit tunnel
setup protocol before they can be used to carry data.
A tunnel MUST NOT be used if there is no route toward the IP address
specified in the Endpoint Sub-TLV or if the route is not advertised
by the router advertising the Tunnel Encapsulation attribute for the
tunnel.
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8. IANA Considerations
8.1. OSPF Router Information
This document requests IANA to allocate a new code point from the
OSPF Router Information (RI) registry.
Value TLV Name Reference
----- ------------------------------------ -------------
TBD1 Tunnel Capabilities This document
8.2. IGP Tunnel Encapsulation Attribute Sub-TLVs Registry
This document requests IANA to create a new registry "IGP Tunnel
Encapsulation Attribute Sub-TLVs" with the following registration
procedure:
Registry Name: IGP Tunnel Encapsulation Attribute Sub-TLVs
Value Name Reference
------- ------------------------------------ -------------
0 Reserved This document
1 Encapsulation This document
2 Protocol Type This document
3 Endpoint This document
4 Color This document
5 Unassigned
6 IP QoS This document
7 UDP Destination Port This document
8-250 Unassigned
251-254 Experimental This document
255 Reserved This document
Assignments of Encapsulation Attribute Types are via Standards Action
[RFC5226].
9. Security Considerations
Security considerations applicable to softwires can be found in the
mesh framework [RFC5565]. In general, security issues of the tunnel
protocols signaled through this OSPF capability extension are
inherited.
If a third-party is able to modify any of the information that is
used to form encapsulation headers, to choose a tunnel type, or to
choose a particular tunnel for a particular payload type, user data
packets may end up getting misrouted, misdelivered, and/or dropped.
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Security considerations for the base OSPF protocol are covered in
[RFC2328] and [RFC5340].
10. Contributors
Uma Chunduri
Huawei
Email: uma.chunduri@gmail.com
11. Acknowledgements
This document is partially inspired by [RFC5512].
The authors would like to thank Greg Mirsky, John E Drake, Carlos
Pignataro and Karsten Thomann for their valuable comments on this
document. Special thanks should be given to Acee Lindem for his
detailed reviews of this document.
12. References
12.1. Normative References
[I-D.ietf-idr-tunnel-encaps]
Rosen, E., Patel, K., and G. Velde, "The BGP Tunnel
Encapsulation Attribute", draft-ietf-idr-tunnel-encaps-06
(work in progress), June 2017.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>.
[RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and
S. Shaffer, "Extensions to OSPF for Advertising Optional
Router Capabilities", RFC 7770, DOI 10.17487/RFC7770,
February 2016, <http://www.rfc-editor.org/info/rfc7770>.
12.2. Informative References
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[I-D.ietf-bier-architecture]
Wijnands, I., Rosen, E., Dolganow, A., Przygienda, T., and
S. Aldrin, "Multicast using Bit Index Explicit
Replication", draft-ietf-bier-architecture-07 (work in
progress), June 2017.
[I-D.ietf-bier-mpls-encapsulation]
Wijnands, I., Rosen, E., Dolganow, A., Tantsura, J.,
Aldrin, S., and I. Meilik, "Encapsulation for Bit Index
Explicit Replication in MPLS and non-MPLS Networks",
draft-ietf-bier-mpls-encapsulation-07 (work in progress),
June 2017.
[I-D.xu-mpls-unified-source-routing-instruction]
Xu, X., Bryant, S., Raszuk, R., Chunduri, U., Contreras,
L., Jalil, L., Assarpour, H., Velde, G., Tantsura, J., and
S. Ma, "Unified Source Routing Instruction using MPLS
Label Stack", draft-xu-mpls-unified-source-routing-
instruction-02 (work in progress), June 2017.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,
DOI 10.17487/RFC2328, April 1998,
<http://www.rfc-editor.org/info/rfc2328>.
[RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008,
<http://www.rfc-editor.org/info/rfc5340>.
[RFC5512] Mohapatra, P. and E. Rosen, "The BGP Encapsulation
Subsequent Address Family Identifier (SAFI) and the BGP
Tunnel Encapsulation Attribute", RFC 5512,
DOI 10.17487/RFC5512, April 2009,
<http://www.rfc-editor.org/info/rfc5512>.
[RFC5565] Wu, J., Cui, Y., Metz, C., and E. Rosen, "Softwire Mesh
Framework", RFC 5565, DOI 10.17487/RFC5565, June 2009,
<http://www.rfc-editor.org/info/rfc5565>.
[RFC7490] Bryant, S., Filsfils, C., Previdi, S., Shand, M., and N.
So, "Remote Loop-Free Alternate (LFA) Fast Reroute (FRR)",
RFC 7490, DOI 10.17487/RFC7490, April 2015,
<http://www.rfc-editor.org/info/rfc7490>.
Authors' Addresses
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Xiaohu Xu (editor)
Huawei
Email: xuxiaohu@huawei.com
Bruno Decraene (editor)
Orange
Email: bruno.decraene@orange.com
Robert Raszuk
Bloomberg LP
Email: robert@raszuk.net
Luis M. Contreras
Telefonica I+D
Email: luismiguel.contrerasmurillo@telefonica.com
Luay Jalil
Verizon
Email: luay.jalil@verizon.com
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