Abstract: Reword last sentence of Abstract from:

The statelessness of SRv6 and its ability to control both
service layer path and underlying transport can be beneficial to the
mobile user-plane, providing flexibility, end-to-end network slicing,
and SLA control for various applications.

to:

The statelessness of SRv6, and its ability to control both
service layer path and underlying transport, can be beneficial to the
mobile user-plane through providing flexibility, end-to-end network slicing,
and SLA control for various applications.

Introduction: In the Introduction change this:

   Segment Routing [RFC8402] is a source routing architecture: a node
   steers a packet through an ordered list of instructions called
   "segments". 

to:

   Segment Routing [RFC8402] is a source routing architecture where a node
   steers a packet through an ordered list of instructions called
   "segments". 

2.1 DN is used to define Uplink/Downlink but DN isn't defined until later in document:

Uplink: from the UE towards the DN
Downlink: from the DN towards the UE

Add a definition for DN.

2.2 Conventions. Need to define gNB before first use:

   *  gNB::1 is an IPv6 address (SID) assigned to the gNB.

5.3.3.  Extensions to the interworking mechanisms

Change "presented" below to "present" or "have presented":
   In this section we presented two mechanisms for interworking with
   gNBs and UPFs that do not support SRv6. 

9.  Control Plane Considerations

Change this:
   This document focuses on user-plane behavior and its independence
   from the control plane.  While the SRv6 mobile user-plane behaviors
   may be utilized in emerging architectures, such as
   [I-D.gundavelli-dmm-mfa], [I-D.mhkk-dmm-srv6mup-architecture] for
   example, require control plane support for the user-plane, this
   document does not impose any change to the existent mobility control
   plane.

To something more understandable such as:

   This document focuses on user-plane behavior and its independence
   from the control plane.  While the SRv6 mobile user-plane behaviors
   may be utilized in emerging architectures, such as
   [I-D.gundavelli-dmm-mfa] and [I-D.mhkk-dmm-srv6mup-architecture] 
   which require control plane support for the user-plane, this
   document does not impose any change to the existent mobility control
   plane.

10.  Security Considerations

Change this:
   The security considerations for Segment Routing are discussed in
   [RFC8402].  More specifically for SRv6 the security considerations
   and the mechanisms for securing an SR domain are discussed in
   [RFC8754].

to this:
   The security considerations for Segment Routing are discussed in
   [RFC8402].  The security considerations for SRv6, and the mechanisms 
   for securing an SR domain, are discussed in [RFC8754].