1. Softwires Hub & Spoke using L2TPv3
Bill Storer

2. L2TPv3 (RFC 3931) Improvements
Supports multiple encapsulations
UDP
IP (Protocol 115)
Supports multiple payload types
PPP IP
Supports enhanced security
Message digest on every control message
Lightweight cookie on data messages
L2TPv3 supports VCCV
Enhanced diagnostic and fault detection

3. Which improvements should we use?
UDP vs IP encapsulation
UDP MUST be supported
NAT
IP (Protocol 115) MUST be supported
Stated in RFC
PPP vs IP payload
PPP MUST be supported
Easiest to integrate with existing L2TPv2 support
IP SHOULD be supported
Enhanced security
Use of enhanced security is optional
MUST support message digest if requested
MUST support cookie if requested
VCCV
MAY be supported as needed

4. Use of the IP Pseudowire
Authentication may be provided using tunnel authentication
Host Name AVP is the user name
A shared secret is associated with the SI’s host name on the SC
Host Name and shared secret may be provided to the SI just as the PPP user name and password are provided
Only one user per tunnel, which is standard for H&S
PANA is also an option for Authentication
draft-ietf-pana-pana-12

5. Use of the IP Pseudowire (cont)
IP address assignment
DHCP for IPv4
Stateless auto config and/or DHCPv6 for IPv6
No new AVPs necessary

6. Use of the PPP Pseudowire
PPP authentication may be used (same as L2TPv2)
Tunnel authentication as in the IP Pseudowire
IPv4 address assignment
IPCP MUST be used for initial address assignment
DHCP MUST be used for prefix delegation
IPv6 address assignment
IPv6CP MUST be used to determine the Interface ID portion of the address
DHCPv6 or stateless autoconfig may be used for the prefix portion of the address
DHCPv6 MUST be used for prefix delegation

7. L2TPv3 Message Details

8. SCCRQ Message MUST AVPs MAY AVPs Host Name Router ID
May be used to authenticate end user
May be “Softwires” if no authentication
Router ID
MUST NOT be sent for Softwires
Marked as MUST, but only for LAC-LAC applications.
Pseudowire Capabilities List
IP, PPP, or both
Others
As specified in the draft
MAY AVPs
Control Connection Tie Breaker
Should never be a tie
Others as needed

9. SCCRP Message MUST AVPs MAY AVPs Host Name Router ID
May be used to authenticate end user
May be “Softwires” if no authentication
Router ID
MUST NOT be sent for Softwires
Marked as MUST, but only for LAC-LAC applications.
Pseudowire Capabilities List
IP, PPP, or both
Others
As specified in the draft
MAY AVPs
As needed

10. SCCCN and StopCCN Messages
MUST AVPs
As specified in the draft
MAY AVPs
As needed

11. HELLO Message We need the HELLO message MUST AVPs MAY AVPs
Don’t have any other keep alive message for IP Pseudowire
Prefer to use the HELLO instead of the LCP echo for PPP Pseudowire
MUST AVPs
As specified in the draft
MAY AVPs

12. ICRQ Message MUST AVPs Pseudowire Type Remote End ID Circuit Status
IP or PPP
Remote End ID
MUST NOT be sent for Softwires
Marked as MUST, but only for LAC-LAC applications.
Circuit Status
New and Active bits set
Others
As specified in the draft

13. ICRQ Message (cont) MAY AVPs Session Tie Breaker Data Sequencing
Should be no ties
Data Sequencing
Shouldn’t be necessary
Others
As specified in the draft

14. ICRP Message MUST AVPs MAY AVPs Circuit Status Others Data Sequencing
New and Active bits set
Others
As specified in the draft
MAY AVPs
Data Sequencing
Shouldn’t be necessary

15. ICCN Message MUST AVPs MAY AVPs As specified in the draft
Data Sequencing
Shouldn’t be necessary
Others

16. CDN Message
MUST AVPs
As specified in the draft
MAY AVPs
As needed

17. SLI and WEN Messages SLI is not relevant to softwires
Change in circuit status disconnects call
No special information needs to be sent after the call is established
WEN is not relevant to softwires
Softwires uses voluntary tunneling

18. Explicit Ack Message Necessary if using authentication MAY AVPs
As specified in the draft

19. PPP Payload Specifics draft-ietf-l2tpext-l2tp-ppp-xx.txt
Discusses transport of PPP over L2TPv3
Forwarding PPP frames
Very similar to L2TPv2
Address and Control fields are NOT transmitted over the tunnel
Only one of the PPP specific AVPs discussed there has relevance to softwires
Offset Size
Use is optional

20. IP Payload Specifics draft-ietf-l2tpext-pwe3-ip-xx.txt
Discusses transport of IP over L2TPv3
Not very relevant to Softwires
Needed to define the IP payload type