Code change:
MUST be zero. The application can specify its preferred policy regarding the use of <del> BUNDLE, the multiplexing mechanism defined in RFC8843.  Regardless of policy, the application will always try to negotiate bundle onto a single transport and will offer a single bundle group across all "m=" sections; use of this single transport is contingent upon the answerer accepting bundle.  However, by specifying a policy from the list below, the application can control exactly how aggressively it will try to bundle media streams together, which affects how it will interoperate with a non-bundle-aware endpoint.  When negotiating with a non-bundle-aware endpoint, only the streams not marked as bundle- only streams will be established. </del> <ins> BUNDLE, the multiplexing mechanism defined in I-D.ietf-mmusic- rfc8843-bis.  Regardless of policy, the application will always try to negotiate bundle onto a single transport and will offer a single bundle group across all "m=" sections; use of this single transport is contingent upon the answerer accepting bundle.  However, by specifying a policy from the list below, the application can control exactly how aggressively it will try to bundle media streams together, which affects how it will interoperate with a non-bundle- aware endpoint.  When negotiating with a non-bundle-aware endpoint, only the streams not marked as bundle-only streams will be established. </ins> The set of available policies is as follows:

Related discussion:
text: In the rewritten offer the 3PCC controller will set the port value to zero (and include an SDP 'bundle-only' attribute) for each "m=" section within the BUNDLE group, excluding the offerer-tagged "m=" section. __ From: Roman Shpount Sent: Tuesday, November 2, 2021 6:33 PM To: Christer Holmberg Cc: Justin Uberti ; Justin Uberti ; RTCWeb IETF Subject: Re: [rtcweb] Working Group Last Call for draft-uberti-rtcweb-rfc8829bis-URL How about we replace the SIP Considerations with: 3PCC Considerations In some 3PCC scenarios, an offer generated during an ongoing session, i.e., a subsequent offer, will be used by a 3PCC controller to establish a new session and forwarded as an initial offer to another endpoint that is currently not part of a session. For example, the Session Initiation Protocol (SIP) [RFC3261] allows a User Agent Client (UAC) to send a re-INVITE request without an SDP body (sometimes referred to as an empty re-INVITE). In such cases, the User Agent Server (UAS) will include an SDP offer in the associated 200 OK response. If UAS is a part of an ongoing session, it will include a subsequent offer in the 200 OK response. The offer will be received by a 3PCC controller (UAC) and then forwarded to another User Agent (UA) as an initial offer. When the BUNDLE mechanism is used, an initial BUNDLE offer is constructed using different rules than subsequent BUNDLE offers. It cannot be assumed that a subsequent offer is a valid initial offer and that the endpoint that expects an initial offer will properly process such a subsequent offer. Therefore, the 3PCC controller SHOULD rewrite the subsequent offer into a valid initial offer before it is used to establish a new session. To make the subsequent offer a valid initial offer, 3PCC will need to modify all the non-tagged m= lines to include the bundle-only attribute and set the m= line port to zero.