Skip to main content

BGP Signaling of MASQUE Tunnel Encapsulation
draft-rosomakho-idr-bgp-masque-tunnel-00

Document Type Active Internet-Draft (individual)
Authors Yaroslav Rosomakho , Alvaro Retana
Last updated 2026-06-29
RFC stream (None)
Intended RFC status (None)
Formats
Stream Stream state (No stream defined)
Consensus boilerplate Unknown
RFC Editor Note (None)
IESG IESG state I-D Exists
Telechat date (None)
Responsible AD (None)
Send notices to (None)
draft-rosomakho-idr-bgp-masque-tunnel-00
IDR Working Group                                           Y. Rosomakho
Internet-Draft                                                   Zscaler
Intended status: Standards Track                               A. Retana
Expires: 31 December 2026                   Futurewei Technologies, Inc.
                                                            29 June 2026

              BGP Signaling of MASQUE Tunnel Encapsulation
                draft-rosomakho-idr-bgp-masque-tunnel-00

Abstract

   This document defines BGP Tunnel Encapsulation Attribute tunnel types
   for MASQUE CONNECT-TCP, CONNECT-UDP, CONNECT-IP, and CONNECT-
   ETHERNET.  It also defines URI Template and ALPN Sub-TLVs for
   advertising the MASQUE proxy endpoint, the HTTP request target
   template, and the application-layer protocol constraints used to
   establish the corresponding MASQUE tunnel.

About This Document

   This note is to be removed before publishing as an RFC.

   The latest revision of this draft can be found at
   https://yaroslavros.github.io/bgp-masque-tunnel/draft-rosomakho-idr-
   bgp-masque-tunnel.html.  Status information for this document may be
   found at https://datatracker.ietf.org/doc/draft-rosomakho-idr-bgp-
   masque-tunnel/.

   Discussion of this document takes place on the IDR Working Group
   mailing list (mailto:idr@ietf.org), which is archived at
   https://mailarchive.ietf.org/arch/browse/idr/.  Subscribe at
   https://www.ietf.org/mailman/listinfo/idr/.

   Source for this draft and an issue tracker can be found at
   https://github.com/yaroslavros/bgp-masque-tunnel.

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 https://datatracker.ietf.org/drafts/current/.

Rosomakho & Retana      Expires 31 December 2026                [Page 1]
Internet-Draft       BGP MASQUE Tunnel Encapsulation           June 2026

   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 31 December 2026.

Copyright Notice

   Copyright (c) 2026 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 (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Conventions and Definitions . . . . . . . . . . . . . . . . .   4
   3.  MASQUE Tunnel Encapsulation . . . . . . . . . . . . . . . . .   4
     3.1.  CONNECT-TCP Tunnel Type . . . . . . . . . . . . . . . . .   5
     3.2.  CONNECT-UDP Tunnel Type . . . . . . . . . . . . . . . . .   6
     3.3.  CONNECT-IP Tunnel Type  . . . . . . . . . . . . . . . . .   6
     3.4.  CONNECT-ETHERNET Tunnel Type  . . . . . . . . . . . . . .   6
   4.  URI Template Sub-TLV  . . . . . . . . . . . . . . . . . . . .   6
   5.  ALPN Sub-TLV  . . . . . . . . . . . . . . . . . . . . . . . .   7
   6.  Use with BGP NLRI . . . . . . . . . . . . . . . . . . . . . .   8
   7.  Operational Considerations  . . . . . . . . . . . . . . . . .   9
     7.1.  URI Template Length . . . . . . . . . . . . . . . . . . .  10
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
     8.1.  BGP Tunnel Encapsulation Attribute Tunnel Types . . . . .  12
     8.2.  BGP Tunnel Encapsulation Attribute Sub-TLVs . . . . . . .  12
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  12
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  12
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  14
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  14
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

Rosomakho & Retana      Expires 31 December 2026                [Page 2]
Internet-Draft       BGP MASQUE Tunnel Encapsulation           June 2026

1.  Introduction

   The BGP Tunnel Encapsulation Attribute [BGP-TUNNEL-ENCAP-ATTR] allows
   BGP speakers to advertise the tunnel encapsulation information
   associated with reachability information carried in BGP UPDATE
   messages.  It is used to indicate that traffic associated with a
   route can be carried using a particular tunnel encapsulation and to
   provide the parameters needed to establish or use that tunnel.

   MASQUE defines mechanisms for proxying traffic using HTTP.  These
   mechanisms include proxying UDP payloads using CONNECT-UDP
   [CONNECT-UDP], proxying IP packets using CONNECT-IP [CONNECT-IP],
   proxying TCP connections using CONNECT-TCP [CONNECT-TCP], and
   proxying Ethernet frames using CONNECT-ETHERNET [CONNECT-ETHERNET].
   These mechanisms allow traffic to be carried over HTTP/1.1
   [HTTP/1.1], HTTP/2 [HTTP/2], or HTTP/3 [HTTP/3] connections to a
   MASQUE proxy and are applicable to environments such as SD-WAN, data
   center interconnect, VPN services, and other overlay connectivity
   deployments.

   In some deployments, BGP is already used as the control plane for
   advertising reachability and associated tunnel encapsulation
   information.  Allowing BGP to advertise MASQUE tunnel encapsulation
   parameters enables a BGP speaker to signal that traffic associated
   with a route is reachable through a MASQUE proxy using one of the
   template-driven CONNECT mechanisms.  This document defines BGP Tunnel
   Encapsulation Attribute tunnel types for CONNECT-TCP, CONNECT-UDP,
   CONNECT-IP, and CONNECT-ETHERNET.

   This document also defines a URI Template Sub-TLV for the BGP Tunnel
   Encapsulation Attribute.  The URI Template identifies the MASQUE
   proxy endpoint and provides the template used to construct the HTTP
   request target for the corresponding CONNECT request.  In addition,
   because MASQUE tunnels can be established over different HTTP
   versions, this document defines an ALPN Sub-TLV that can be used to
   indicate the application-layer protocols supported or preferred for
   use with the advertised tunnel.

   This document does not define new BGP NLRI, does not define a new
   MASQUE protocol mechanism, and does not define a new proxy
   authentication or authorization mechanism.  The NLRI to which the
   Tunnel Encapsulation Attribute is attached identifies the traffic,
   service, or reachability information to which the MASQUE tunnel
   applies.  Authentication and authorization of the MASQUE proxy remain
   the responsibility of the endpoints and the applicable HTTP and TLS
   mechanisms.

Rosomakho & Retana      Expires 31 December 2026                [Page 3]
Internet-Draft       BGP MASQUE Tunnel Encapsulation           June 2026

2.  Conventions and Definitions

   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
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   This document uses terminology from [BGP-TUNNEL-ENCAP-ATTR],
   [CONNECT-UDP], [CONNECT-IP], [CONNECT-TCP], and [CONNECT-ETHERNET].

   MASQUE proxy:  An HTTP proxy that supports one or more of the MASQUE
      CONNECT mechanisms identified by the tunnel types defined in this
      document.

   MASQUE tunnel:  A tunnel established using one of the CONNECT
      mechanisms identified by the tunnel types defined in this
      document.

   URI Template:  A URI Template as defined by [URI-TEMPLATE].  In this
      document, a URI Template is carried in the URI Template Sub-TLV
      and is used to construct the HTTP request target for a MASQUE
      tunnel.

   ALPN:  Application-Layer Protocol Negotiation, as defined by [ALPN].

3.  MASQUE Tunnel Encapsulation

   A Tunnel Encapsulation TLV using one of the tunnel types defined in
   this document identifies a MASQUE proxy and the corresponding HTTP
   request target using the URI Template Sub-TLV defined in Section 4.
   The URI Template determines the MASQUE proxy endpoint and is used to
   construct the HTTP request for the corresponding CONNECT mechanism.

   An ALPN Sub-TLV, defined in Section 5, MAY be included to indicate
   the application-layer protocols supported or preferred for use when
   connecting to the MASQUE proxy.

   The tunnel types defined in this section identify the MASQUE
   mechanism used to carry the traffic associated with the BGP route.
   The NLRI to which the Tunnel Encapsulation Attribute is attached
   determines the traffic, service, or reachability information to which
   the MASQUE tunnel applies.

Rosomakho & Retana      Expires 31 December 2026                [Page 4]
Internet-Draft       BGP MASQUE Tunnel Encapsulation           June 2026

   A Tunnel Encapsulation TLV whose tunnel type is one of the MASQUE
   tunnel types defined in this document is referred to as a MASQUE
   Tunnel Encapsulation TLV.  A MASQUE Tunnel Encapsulation TLV MUST
   contain exactly one URI Template Sub-TLV and MAY contain at most one
   ALPN Sub-TLV.

   Only the following Sub-TLVs are applicable to MASQUE Tunnel
   Encapsulation TLVs:

                          +==============+======+
                          | Sub-TLV      | Code |
                          +==============+======+
                          | Color        | 4    |
                          +--------------+------+
                          | DS Field     | 7    |
                          +--------------+------+
                          | URI Template | TBD5 |
                          +--------------+------+
                          | ALPN         | TBD6 |
                          +--------------+------+

                             Table 1: Sub-TLVs
                            allowed for use with
                               MASQUE Tunnel
                             Encapsulation TLVs

   All other Sub-TLVs not explicitly listed above are not defined for
   use with MASQUE Tunnel Encapsulation TLVs.  Receivers MUST ignore
   these Sub-TLVs when validating MASQUE-specific semantics.  Future
   specifications MAY define additional Sub-TLVs for use with MASQUE
   Tunnel Encapsulation TLVs.

   If a MASQUE Tunnel Encapsulation TLV contains no URI Template Sub-
   TLV, or contains more than one URI Template Sub-TLV, it MUST be
   ignored.

3.1.  CONNECT-TCP Tunnel Type

   The CONNECT-TCP Tunnel Type indicates that traffic associated with
   the route is to be carried using CONNECT-TCP [CONNECT-TCP].  This
   tunnel type is applicable to routes or service-specific information
   that identify TCP connectivity or TCP flow steering.

      Name: MASQUE CONNECT-TCP Tunnel Type: TBD1 Length: 0

Rosomakho & Retana      Expires 31 December 2026                [Page 5]
Internet-Draft       BGP MASQUE Tunnel Encapsulation           June 2026

3.2.  CONNECT-UDP Tunnel Type

   The CONNECT-UDP Tunnel Type indicates that traffic associated with
   the route is to be carried using CONNECT-UDP [CONNECT-UDP].  This
   tunnel type is applicable to routes or service-specific information
   that identify UDP connectivity or UDP flow steering.

      Name: MASQUE CONNECT-UDP Tunnel Type: TBD2 Length: 0

3.3.  CONNECT-IP Tunnel Type

   The CONNECT-IP Tunnel Type indicates that traffic associated with the
   route is to be carried using CONNECT-IP [CONNECT-IP].  This tunnel
   type is applicable to routes that identify IP reachability, such as
   IP prefixes, VPN-IP routes, or other service-specific IP reachability
   information.

      Name: MASQUE CONNECT-IP Tunnel Type: TBD3 Length: 0

3.4.  CONNECT-ETHERNET Tunnel Type

   The CONNECT-ETHERNET Tunnel Type indicates that traffic associated
   with the route is to be carried using CONNECT-ETHERNET
   [CONNECT-ETHERNET].  This tunnel type is applicable to routes that
   identify Ethernet or Layer 2 service reachability, such as EVPN or
   other service-specific Layer 2 reachability information.

      Name: MASQUE CONNECT-ETHERNET Tunnel Type: TBD4 Length: 0

4.  URI Template Sub-TLV

   The URI Template Sub-TLV identifies the MASQUE proxy endpoint and
   provides the template used to construct the HTTP request target for
   the MASQUE tunnel.  The URI Template Sub-TLV is carried in a MASQUE
   Tunnel Encapsulation TLV.

   The URI Template Sub-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=TBD5   |           Length              |               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+               |
    ~                     URI Template Value                        ~
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                       Figure 1: URI Template Sub-TLV

Rosomakho & Retana      Expires 31 December 2026                [Page 6]
Internet-Draft       BGP MASQUE Tunnel Encapsulation           June 2026

   Type:  TBD5

   Length:  The length, in octets, of the URI Template Value field.

   URI Template Value:  A UTF-8 encoded URI Template [URI-TEMPLATE].

   The URI Template Value MUST be a syntactically valid URI Template.
   The URI Template MUST be in absolute form and MUST include non-empty
   scheme, authority, and path components.  The URI Template MUST
   satisfy the URI Template requirements of the MASQUE mechanism
   identified by the enclosing MASQUE Tunnel Encapsulation TLV.

   The authority component of the URI Template identifies the MASQUE
   proxy endpoint to which the receiver establishes the HTTP connection.
   The path and query components of the expanded URI identify the
   request target used for the corresponding CONNECT mechanism.

   If the URI Template Value is not a syntactically valid URI Template,
   if it is not in absolute form, if it does not include non-empty
   scheme, authority, and path components, or if it is otherwise not
   usable with the MASQUE mechanism identified by the enclosing MASQUE
   Tunnel Encapsulation TLV, the MASQUE Tunnel Encapsulation TLV MUST be
   ignored.

   The Tunnel Egress Endpoint Sub-TLV defined by [BGP-TUNNEL-ENCAP-ATTR]
   is not used with MASQUE Tunnel Encapsulation TLVs because the
   authority component of the URI Template identifies the MASQUE proxy
   endpoint and provides the information necessary to establish the
   corresponding HTTP connection.

5.  ALPN Sub-TLV

   The ALPN Sub-TLV indicates the application-layer protocol or
   protocols that are supported or preferred for use with the tunnel
   described by the enclosing Tunnel Encapsulation TLV.  When used with
   a MASQUE Tunnel Encapsulation TLV, the ALPN Sub-TLV identifies the
   HTTP version or versions that can be used to establish the
   corresponding MASQUE tunnel.

   The ALPN Sub-TLV has the following format:

Rosomakho & Retana      Expires 31 December 2026                [Page 7]
Internet-Draft       BGP MASQUE Tunnel Encapsulation           June 2026

     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=TBD6   |           Length              |               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+               |
    ~                       ALPN ProtocolNameList                   ~
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                           Figure 2: ALPN Sub-TLV

   Type:  TBD6

   Length:  The length, in octets, of the ALPN ProtocolNameList field.

   ALPN ProtocolNameList:  A sequence of one or more ALPN protocol
      identifiers, encoded as a TLS ALPN ProtocolNameList as defined in
      Section 3.1 of [ALPN].

   The ALPN ProtocolNameList field contains one or more non-empty ALPN
   protocol identifiers.  The order of ALPN protocol identifiers
   indicates preference, with the most preferred protocol listed first.

   When the ALPN Sub-TLV is present in a MASQUE Tunnel Encapsulation
   TLV, the receiver MUST use one of the advertised ALPN protocol
   identifiers when establishing the HTTP connection to the MASQUE
   proxy.  If none of the advertised protocol identifiers is supported
   by the receiver, the MASQUE Tunnel Encapsulation TLV MUST be ignored.

   A MASQUE Tunnel Encapsulation TLV MUST contain at most one ALPN Sub-
   TLV.  If more than one ALPN Sub-TLV is present, the MASQUE Tunnel
   Encapsulation TLV MUST be ignored.

   If the ALPN Sub-TLV is malformed, including if it contains an empty
   ProtocolNameList or an empty protocol identifier, the MASQUE Tunnel
   Encapsulation TLV MUST be ignored.

6.  Use with BGP NLRI

   The tunnel types and Sub-TLVs defined in this document are used with
   the BGP Tunnel Encapsulation Attribute.  This document does not
   define new BGP NLRI or new procedures for associating tunnel
   encapsulation information with routes.

Rosomakho & Retana      Expires 31 December 2026                [Page 8]
Internet-Draft       BGP MASQUE Tunnel Encapsulation           June 2026

   The NLRI to which the Tunnel Encapsulation Attribute is attached
   identifies the traffic, service, or reachability information to which
   the MASQUE tunnel applies.  The tunnel type in the Tunnel
   Encapsulation TLV identifies the MASQUE mechanism used to carry that
   traffic.

   The following examples illustrate possible uses:

   *  A route that identifies IP reachability, such as an IP prefix or
      VPN-IP route, can use the CONNECT-IP, CONNECT-TCP, or CONNECT-UDP
      Tunnel Types to indicate that matching IP, TCP, or UDP traffic
      packets are carried using the correspondind CONNECT mechanism.

   *  A route that identifies Ethernet or Layer 2 service reachability,
      such as an EVPN route, can use the CONNECT-ETHERNET Tunnel Type to
      indicate that matching Ethernet frames are carried using CONNECT-
      ETHERNET.

   Specifications or deployment profiles that use the tunnel types
   defined in this document may define additional rules for their use
   with particular AFI/SAFI combinations or service models.

7.  Operational Considerations

   The tunnel types and Sub-TLVs defined in this document allow BGP to
   advertise MASQUE tunnel encapsulation parameters associated with BGP
   routes.  Operators MUST ensure that these attributes are propagated
   only within routing domains where the advertised MASQUE proxy
   information is intended to be used.

   A URI Template carried in BGP can reveal information about proxy
   names, service structure, or internal topology.  Operators MUST apply
   BGP import and export policy to avoid leaking MASQUE tunnel
   encapsulation information outside the intended administrative scope.

   Multiple MASQUE tunnel candidates can be advertised by including
   multiple Tunnel Encapsulation TLVs, each containing a single URI
   Template Sub-TLV.  This can be used to advertise alternative MASQUE
   proxies.  Selection among available tunnel candidates is left to
   local policy and outside the scope of this specification.

   A BGP Tunnel Encapsulation Attribute MAY contain both MASQUE Tunnel
   Encapsulation TLVs and Tunnel Encapsulation TLVs of other tunnel
   types defined by [BGP-TUNNEL-ENCAP-ATTR] or subsequent
   specifications.  This document does not define any preference between
   MASQUE and non-MASQUE tunnel types.  Selection among available tunnel
   types is determined by local policy and the procedures applicable to
   the associated AFI/SAFI.

Rosomakho & Retana      Expires 31 December 2026                [Page 9]
Internet-Draft       BGP MASQUE Tunnel Encapsulation           June 2026

   Operators should consider the stability of URI Template values when
   attaching MASQUE Tunnel Encapsulation TLVs to routes.  Frequent
   changes to URI Templates, can increase route churn.  Deployments that
   advertise the same MASQUE proxy parameters for many routes should
   consider existing BGP mechanisms and service-specific profiles that
   avoid unnecessary repetition.

7.1.  URI Template Length

   [URI-TEMPLATE] does not define a general maximum length for a URI
   Template.  When a URI Template is carried in the URI Template Sub-
   TLV, the length of the URI Template Value is constrained by the Sub-
   TLV encoding and by the size of the BGP UPDATE message in which the
   Sub-TLV is carried.

   The URI Template Sub-TLV uses a two-octet Length field.  This allows
   the URI Template Value to be longer than 255 octets.  However, long
   URI Template Values can significantly increase the size of the
   enclosing BGP UPDATE message and can affect propagation across BGP
   sessions where BGP Extended Messages [BGP-EXTENDED-MESSAGES] are not
   used.

   URI Template Values SHOULD NOT exceed 1024 octets and should be kept
   as short as practical.

   Deployments that carry URI Template Sub-TLVs SHOULD use BGP Extended
   Messages [BGP-EXTENDED-MESSAGES] on the BGP sessions over which the
   corresponding routes are propagated.  If BGP Extended Messages are
   not available, URI Template Values MUST be kept small enough that the
   complete BGP UPDATE message, including all path attributes, NLRI, and
   protocol overhead, does not exceed 4096 octets.

   If the URI Template Value exceeds the receiver's supported or
   configured limit, the receiver SHOULD ignore the enclosing MASQUE
   Tunnel Encapsulation TLV.

   If the length of the URI Template results in the BGP UPDATE exceeding
   the maximum message size, the result may include a lack of
   reachability, as detailed in [BGP-EXTENDED-MESSAGES].  If BGP
   Extended Messages are partially supported, the BGP Tunnel
   Encapsulation Attribute may be discarded [BGP-EXTENDED-MESSAGES], as
   it is eligible under the "attribute discard" approach of
   [BGP-ERROR-HANDLING], which would result in the information not
   reaching the intended recipients. # Security Considerations

   The security considerations of [BGP-TUNNEL-ENCAP-ATTR],
   [CONNECT-UDP], [CONNECT-IP], [CONNECT-TCP], [CONNECT-ETHERNET],
   [URI-TEMPLATE], and [ALPN] apply.

Rosomakho & Retana      Expires 31 December 2026               [Page 10]
Internet-Draft       BGP MASQUE Tunnel Encapsulation           June 2026

   This document defines BGP signaling for MASQUE tunnel encapsulation
   parameters.  It does not define a new authentication or authorization
   mechanism for MASQUE proxies, and it does not change the security
   properties of the MASQUE mechanisms identified by the tunnel types
   defined in this document.

   Authorization to use the MASQUE proxy, including authorization to
   reach the requested target or to carry the traffic associated with
   the route, is enforced by the MASQUE proxy and the applicable
   mechanisms.  Implementations MUST NOT treat possession of a BGP route
   or Tunnel Encapsulation Attribute as sufficient authorization to use
   a MASQUE proxy.

   Misconfiguration, route leaks, or malicious injection of BGP routes
   carrying MASQUE tunnel encapsulation information can cause traffic to
   be directed to an unintended MASQUE proxy.  This can result in
   traffic interception, denial of service, policy bypass, or loss of
   connectivity.  Operators should apply the same route filtering,
   origin validation, session protection, and import/export policy
   controls used for other BGP routes carrying tunnel encapsulation
   information.  For more details, see Section 11 of
   [BGP-TUNNEL-ENCAP-ATTR].

   The URI Template Sub-TLV can reveal information about proxy
   hostnames, service structure, tenant identifiers, or internal
   topology.  Such information can be sensitive.  Operators should
   ensure that routes carrying MASQUE Tunnel Encapsulation TLVs are
   distributed only within the administrative scope where the
   corresponding MASQUE proxy information is intended to be visible.

   The URI Template carried in BGP is used to construct an HTTP request
   target.  Implementations MUST validate the URI Template before use
   and MUST apply the processing rules in this document and in the
   applicable MASQUE specification.  Implementations MUST NOT expand or
   use a URI Template in a way that creates a request target outside the
   scope intended by the received route and local policy.

   The ALPN Sub-TLV can constrain the application-layer protocols used
   to establish a MASQUE tunnel.  If an ALPN Sub-TLV is present,
   receivers MUST use only one of the advertised ALPN protocol
   identifiers for the corresponding tunnel.  Ignoring an ALPN
   constraint could cause a receiver to use an HTTP version or transport
   that the advertising speaker did not intend to support for that
   tunnel.

Rosomakho & Retana      Expires 31 December 2026               [Page 11]
Internet-Draft       BGP MASQUE Tunnel Encapsulation           June 2026

8.  IANA Considerations

   IANA is requested to update the "BGP Tunnel Encapsulation" registry
   group as specified in the following sections.

8.1.  BGP Tunnel Encapsulation Attribute Tunnel Types

   IANA is requested to allocate the following values from the "BGP
   Tunnel Encapsulation Attribute Tunnel Types" registry:

               +=======+==================+===============+
               | Value | Description      | Reference     |
               +=======+==================+===============+
               |  TBD1 | CONNECT-TCP      | this document |
               +-------+------------------+---------------+
               |  TBD2 | CONNECT-UDP      | this document |
               +-------+------------------+---------------+
               |  TBD3 | CONNECT-IP       | this document |
               +-------+------------------+---------------+
               |  TBD4 | CONNECT-ETHERNET | this document |
               +-------+------------------+---------------+

                 Table 2: MASQUE BGP Tunnel Encapsulation
                          Attribute Tunnel Types

8.2.  BGP Tunnel Encapsulation Attribute Sub-TLVs

   IANA is requested to allocate the following values from the 192-252
   range in the "BGP Tunnel Encapsulation Attribute Sub-TLVs" registry:

                 +=======+==============+===============+
                 | Value | Description  | Reference     |
                 +=======+==============+===============+
                 |  TBD5 | URI Template | this document |
                 +-------+--------------+---------------+
                 |  TBD6 | ALPN         | this document |
                 +-------+--------------+---------------+

                        Table 3: MASQUE BGP Tunnel
                     Encapsulation Attribute Sub-TLVs

9.  References

9.1.  Normative References

Rosomakho & Retana      Expires 31 December 2026               [Page 12]
Internet-Draft       BGP MASQUE Tunnel Encapsulation           June 2026

   [ALPN]     Friedl, S., Popov, A., Langley, A., and E. Stephan,
              "Transport Layer Security (TLS) Application-Layer Protocol
              Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301,
              July 2014, <https://www.rfc-editor.org/rfc/rfc7301>.

   [BGP-TUNNEL-ENCAP-ATTR]
              Patel, K., Van de Velde, G., Sangli, S., and J. Scudder,
              "The BGP Tunnel Encapsulation Attribute", RFC 9012,
              DOI 10.17487/RFC9012, April 2021,
              <https://www.rfc-editor.org/rfc/rfc9012>.

   [CONNECT-ETHERNET]
              Sedeño, A., "Proxying Ethernet in HTTP", Work in Progress,
              Internet-Draft, draft-ietf-masque-connect-ethernet-09, 12
              April 2026, <https://datatracker.ietf.org/doc/html/draft-
              ietf-masque-connect-ethernet-09>.

   [CONNECT-IP]
              Pauly, T., Ed., Schinazi, D., Chernyakhovsky, A.,
              Kühlewind, M., and M. Westerlund, "Proxying IP in HTTP",
              RFC 9484, DOI 10.17487/RFC9484, October 2023,
              <https://www.rfc-editor.org/rfc/rfc9484>.

   [CONNECT-TCP]
              Schwartz, B. M., "Template-Driven HTTP CONNECT Proxying
              for TCP", Work in Progress, Internet-Draft, draft-ietf-
              httpbis-connect-tcp-11, 20 March 2026,
              <https://datatracker.ietf.org/doc/html/draft-ietf-httpbis-
              connect-tcp-11>.

   [CONNECT-UDP]
              Schinazi, D., "Proxying UDP in HTTP", RFC 9298,
              DOI 10.17487/RFC9298, August 2022,
              <https://www.rfc-editor.org/rfc/rfc9298>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/rfc/rfc2119>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.

Rosomakho & Retana      Expires 31 December 2026               [Page 13]
Internet-Draft       BGP MASQUE Tunnel Encapsulation           June 2026

   [URI-TEMPLATE]
              Gregorio, J., Fielding, R., Hadley, M., Nottingham, M.,
              and D. Orchard, "URI Template", RFC 6570,
              DOI 10.17487/RFC6570, March 2012,
              <https://www.rfc-editor.org/rfc/rfc6570>.

9.2.  Informative References

   [BGP-ERROR-HANDLING]
              Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K.
              Patel, "Revised Error Handling for BGP UPDATE Messages",
              RFC 7606, DOI 10.17487/RFC7606, August 2015,
              <https://www.rfc-editor.org/rfc/rfc7606>.

   [BGP-EXTENDED-MESSAGES]
              Bush, R., Patel, K., and D. Ward, "Extended Message
              Support for BGP", RFC 8654, DOI 10.17487/RFC8654, October
              2019, <https://www.rfc-editor.org/rfc/rfc8654>.

   [HTTP/1.1] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
              Ed., "HTTP/1.1", STD 99, RFC 9112, DOI 10.17487/RFC9112,
              June 2022, <https://www.rfc-editor.org/rfc/rfc9112>.

   [HTTP/2]   Thomson, M., Ed. and C. Benfield, Ed., "HTTP/2", RFC 9113,
              DOI 10.17487/RFC9113, June 2022,
              <https://www.rfc-editor.org/rfc/rfc9113>.

   [HTTP/3]   Bishop, M., Ed., "HTTP/3", RFC 9114, DOI 10.17487/RFC9114,
              June 2022, <https://www.rfc-editor.org/rfc/rfc9114>.

Acknowledgments

   TODO acknowledge.

Authors' Addresses

   Yaroslav Rosomakho
   Zscaler
   Email: yrosomakho@zscaler.com

   Alvaro Retana
   Futurewei Technologies, Inc.
   Email: aretana@futurewei.com

Rosomakho & Retana      Expires 31 December 2026               [Page 14]