TCP/IP based TML (Transport Mapping Layer) for ForCES Protocol

1. TCP/IP based TML (Transport Mapping Layer) for ForCES Protocol Hormuzd Khosravi Shuchi Chawla Furquan Ansari Jon Maloy 63rd IETF Meeting, Paris

2. Topics • Areas updated • Details on the updates • Opens • Summary

3. Areas Updated • Data Channel Protocol • Addressing • High Availability • TML Messaging • CE-FE Communication Channels • Multicast Model • TML Service Interface • TML Service Interface Usage

4. Data Channel Protocol Protocol related changes • TCP no longer specified as protocol for the data channel • Possible choices: DCCP, rate limited tunneling (for example, GRE) of data traffic • Some experimentation ongoing in this area

5. Addressing Address mapping updates • TML allocates channel descriptors • PL is only aware of CE/FE IDs; unaware of TML channel descriptors • TML maintains mapping between PL layer CE/FE IDs/addresses and the channel descriptors

6. High Availability Clarifications on TML Role • FE TML has no authority to decide which CE to set up communication channels with; outside the scope of TML • TML responsible for keeping the channels up • TML notifies PL if unable to setup the channels

7. TML Messaging Removal of TML Messaging • No TML Layer messaging for control messages • No encapsulation done at the TML layer for control messages • TML transports messages from the PL Layer encapsulated in a TCP/IP header

8. CE-FE Communication Channels Modifications to channel setup • Single TML call by PL to set up channels for control and data messaging • PL unaware of number of channels setup • TML maintains mapping between PL layer addresses (CE/FE IDs) and the channel descriptors it allocates • No TML channel descriptors returned to PL • PL uses the FE/CE IDs for read/write calls and specifies message type (control/data); TML maps to appropriate channel to send the message

9. Multicast Model Multicast configuration changes • CE initiated multicast group setup • TML maintains mapping between PL Layer Multicast IDs and TML assigned channel descriptors • No TML messaging involved in setup of multicast group

10. TML Service Interface • Provides a service interface to an upper layer protocol (PL) • Support for: • Channel setup and shutdown • Multicast group join and leave • Write/send message (unicast or multicast) • Read/receive message • Some of the interfaces modified in terms of functionality or invoking entity

11. TML Service Interface (contd.) • tmlInit: Enable establishment of channels. [CE] • tmlOpen: Set up unicast channels for both control and data messaging. [FE] • tmlClose: Shut down channels for both control and data messaging. [CE or FE] • tmlWrite: Send a control or data message over a channel. [CE or FE] • tmlRead: Read a control or data message over a channel. [CE or FE] • tmlMulticastGroupJoin: Request an FE to join a multicast group. [CE] • tmlMulticastGroupLeave: Request an FE to leave a multicast group. [CE]

12. TML Service Interface Usage: Channel Setup FE PL FE TML CE TML CE PL tmlInit () CE init/ boot up tmlOpen(Cc) Ctrl chan (Cc) setup Setup control channel FeId  [CcDes(ctrl)] Ctrl chan (Cc) rsp CeId  [CcDes(ctrl)] Data chan (Cd) setup Setup data channel FeId  [CcDes(ctrl), CdDes(data)] Data chan (Cd) rsp CeId  [CcDes(ctrl), CdDes(data)] status tmlEvent (chUp) tmlEvent (chUp) Association, capability, topology info STEADY STATE OPERATION tmlWrite (FeId, ctrl) tmlRead(CeId, ctrl)

13. TML Service Interface Usage: Multicast Group Join FE1 PL FE1 TML CE TML CE PL STEADY STATE OPERATION PL level control message MC Grp Join Req (McId) FE TML maintains mapping b/w PL IDs and TML descriptors tmlJoin (McId) McId = {FE1_ChDes} status MC Grp Join Rsp (McId) FE TML maintains mapping b/w PL IDs and TML descriptors tmlJoin (McId) McId = {FE1_ChDes} status tmlWrite (McId) Similarly, FE2 join results in McId = {FE1_ChDes, FE2_ChDes}

14. TML Service Interface Usage: Multicast Group Leave FE1 PL FE1 TML CE TML CE PL STEADY STATE OPERATION PL level control message MC Grp Leave Req (McId) FE TML maintains mapping b/w PL IDs and TML descriptors tmlLeave (McId) McId ={FE2_ChDes} status MC Grp Leave Rsp (McId) tmlLeave (McId) FE TML maintains mapping b/w PL IDs and TML descriptors McId = {FE2_ChDes} status

15. Opens/Under investigation • Protocol for the data messaging between FE and CE • Based on protocol selected, draft would need updates in several areas • Details on security protocol to be used with TML: IPSec and/or TLS

16. Summary • Addressed feedback from the last session on the following: • High Availability • TML Messaging • Multicast Model • TML Service Interface is still currently in this draft; will be moved later to a separate draft • Main area under investigation is the protocol for data messaging

17. Backup

18. Protocol for Data Channel • May need further investigation • Other options: • Datagram Congestion Control Protocol (DCCP) • Provides congestion control but not reliable (which satisfies requirements for data channel) • Experimented with this but no stable implementation available at this point • Generic Routing Encapsulation (GRE) Tunneling • Encapsulate data packets in a GRE header  data channel is a GRE tunnel • Rate limiting may be done by the FE to provide support for congestion control • Consider other tunneling protocols