UDP Encapsulation of 6rd

1
UDP Encapsulation of 6rd

• IETF 76, Hiroshima
• 8 NOV 2009
• Yiu Lee

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UDP Encapsulation of 6rd

• 6rd is a modification to 6to4 which enables a
  Service Provider to offer IPv6 connectivity to
  its customers over an IPv4 network.
• Classic 6rd implementations contain two
  components the 6rd relay and the 6rd CPE, linked
  by the 6rd tunnel.
• 6rd relay is the relay device within the network.
• 6rd CPE is the client device located at the
  customers home.

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UDP Encapsulation of 6rd

• 6rd is difficult to deploy in an environment
  where the SP doesnt control the CPE, or not all
  the CPEs can be upgraded to support the new 6rd
  CPE image.
• We propose an extension to encapsulate 6rd in UDP
  so that 6rd packets can traverse a typical home
  gateway.
• The 6rd relay defined in this specification
  supports both classic 6rd and UDP encap, so SP
  can deploy the UDP encap first and migrate to
  classic 6rd when the customers upgrade their home
  gateway.

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UDP Encapsulation of 6rd

• Comparisons to Softwire Hub-and-Spoke and Teredo
• Softwire and Teredo both offer IPv6 connectivity
  to hosts behind an ordinary home gateway.
• Softwire Hub-and-Spoke
• Softwire Hub-and-Spoke runs on PPP over L2TP. For
  a SP that doesnt use PPP, this technology is
  less attractive.
• Teredo
• Teredo requires an open-relay which enables no
  controls for the inbound relay. It is challenging
  for a SP who wants to provide a reliable relay
  service.

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UDP Encapsulation of 6rd

• The idea is simple when a 6rd host sends a v6
  packet, it will encapsulate the packet with a UDP
  header for delivery over the v4 network.
• The typical home gateway will see the 6rd packet
  as a normal UDP packet and create a binding to
  allow the 6rd packet to pass through.
• Two Models
• Host model where the O/S implements the UDP
  encap.
• Server model where a server implements the UDP
  encap and connects to the home router LAN and
  serves the hosts in the same LAN.

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UDP Encapsulation of 6rd

• Host Model
• IPv6
• Global
  Internet
• -----
• 6rd
  Border Router
• -----
• ----------------------
  
• 
  
• ISP IPv4 Network
  
• 
  
• 
  
• ----------------------
  
• 
  Subscriber IPv4
• -----
• 
  Unmodified HGW
• -----
• Internal
  IPv4
• _________

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UDP Encapsulation of 6rd

• Server Model
• IPv6
• Global
  Internet
• -----
• 6rd
  Border Router
• -----
• ----------------------
  
• 
  
• ISP IPv4 Network
  
• 
  
• 
  
• ----------------------
  
• -----
• 
  Unmodified HGW
• -----
• ___________________________
  _________

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UDP Encapsulation of 6rd

• UDP Encapsulation Format
• 0 1 2
  3
• 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0
  1 2 3 4 5 6 7 8 9 0 1
• ----------------------
  ----------
• Source Port
  Destination Port
• ----------------------
  ----------
• Length
  Checksum
• ----------------------
  ----------
• 6rd Datagram
  
• 
  
• 
  
• ----------------------
  ----------

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UDP Encapsulation of 6rd

• Limitations
• Externally initiated sessions cant reach hosts
  behind home gateway.
• Static Port-forwarding on the home gateway for
  the well-known 6rd UDP port may resolve this
  issue.
• Each host must be served by a particular 6rd
  relay. The 6rd relay must create the binding
  table to remember the UDP session. This binding
  is stateful.

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UDP Encapsulation of 6rd

• Should we adopt this as a WG item?