Unedited Version of SIP-Mobile Minutes:

SIP mobility informal meeting was called upon by Paul Francis of Tahoe Networks in the SIP mobility mailing list, which was later on seconded by Henning Schulzrinne and Faramak Vakil. Paul Francis and Ashutosh Dutta managed to get it arranged in IETF. This meeting lasted for about one and half hour, and several issues were discussed related to SIP based mobility. Henning Schulzrinne led the meeting, and outlined the key factors that need to be discussed after getting the feedback from the members who were present in the room. Because of lack of time and scheduling conflict with other BOFs not all the issues could be discussed in full length.

• Soft Handoff

• L3 ‘virtual’ soft handoff issue – fast handoff, smooth handoff and hiding the location detail

• "Expand mobility management for SIP to every application" has a point?
• S-ftp cool for retry and other functions with help of SDP
• Size of SDP - MMUSIC group discusses this issue, SDP-NG
• SIP API

• Make application SIP URI capable
• Socket / daemon will have a capability to solve SIP URI
• Socket is usually for a single stream application
• SCTP socket may be helpful since it has a group thing.
• If multi session case is considered then…?

• anonymous "authentication" in SIP?
• How to go through the NAT
• comparison SIP based mobility with IP based mobility (i.e. Mobile IP)

• in the case of both ends are moving.
• SIP also can have fallback way to the simultaneous moving by using home registrar.
• SIP server supporting mobility proxy being worked by Columbia Univ.

• Register

• Visiting network may use Firewall and/or NAT. And SIP register isn’t useful because IP address included may not be global reachable.
• 3GPP model explained by Marks Isoki

• How those issues relate to mobility and that supported by SIP?

Need for SIP API - Abstraction for location service

Service mobility:

Soft-handoff - Performance issues - Ability to have same service while changing between networks.

Multicasting using SIP proxy

Link layer characteristics, location update with SIP proxy

Midcom Box, (Proxy and Midcom box can be co-located)

Soft-handoff and virtual soft-handoff both are achievable.

Local buffering to take care of caching like functions

Mobile route optimization:

Both - Split TCP application, and UDP application.

3GPP - register Issue, Subscribe/Notify, use of SDP for messaging for Register options were described.

Mobility services for SIP: 3GPP Networks, Global mobility services

Mobility services: Cross service provider

Pre-call mobility by SIP. Moving from one device to another is not supported by Mobile IP, but is achievable by SIP. External Session (ftp), can this kind of application be started by SIP UA.

FTP session - how to start it as part of SIP UA.

TCP based chat session

Messaging concept - advertise on SDP about the message

S-FTP - TCP connection, start from mid ftp session like

Netscape SMART update

Treat TCP session as short-lived, then it can be done as part of HTTP.

Application needs to be aware of IP address changes

Most of the SIP application are media-in-built, so the application does not need to get restarted.

Can any variety of Mobile IP approach be used to take care of IP address hiding. Question by (Radhika)

Build SIP API.

SIP API which sits in between the signaling and media.

Subset of SIP model.

SIP-SCTP: Can SCTP solve it? How would it work?

Hiding the application from IP address change.

Name based socket instead of IP based socket

If TCP is still the transport mechanism, then there may still be a problem.

SCTP - dynamically change of IP address

Authentication Issues still need to be addressed.

S-MIME - (PKI)

Security for SIP vs. Mobile IP based security services.

Anonymous Authentication comes from the same host

Host Identity Protocol (HIP) : How does that fit in here?

Playback issue:

Difference between SIP mobility and other types of mobility.

When both the hosts move simultaneously, what is the advantage using SIP based mobility?

Use of Contact address:

HOTSIP does similar things with respect to registration and personal mobility.

Registration stuff for 3GPP was described in details

Firewall in the path

3GPP presentation - how SIP can be used in this context?

Router has to know

Proxy

Problems

1. Contact

2. Why does one need to visit home

Load balancing trying to find the proper SIP registrar

Add the Record Route on the SIP server

Proxy CSC contact address:

Security Issues: SIP type security within Visited, IPSec between Visited and Home domains.