Re: [Detnet] IPv6 encapsulation in dataplane doc

["Jouni" <[e-mail]>]

Hi Pascal,

 

Thanks for reading the draft and elaborating the option handling further. In
the current draft Section 6.4.1 elaborates handling/processing of options
further than in the introductory part of the options and packet formats. The
alternative a) below is already described in the draft to some extent - thus
I fully agree. The alternative b) would also fit but there is no explicit
description for it yet - again I fully agree. The figure 11 is heading
exactly where your alternatives point at.

 

Thnaks,

                jouni

 

From: detnet [mailto:[e-mail]] On Behalf Of Pascal Thubert
(pthubert)
Sent: Wednesday, February 7, 2018 15:27 PM
To: [e-mail]
Subject: [Detnet] IPv6 encapsulation in dataplane doc

 

Dear all

 

This is about the IPv6 encapsulation and more precisely

 

                        Therefore, if a DetNet-aware end system only
   inserted the DetNet Destination Option into the IPv6 but e.g., a
   DetNet Edge node is configured to enforce an explicit route for the
   IPv6 packet using a source routing header, then it has no other
   possibility than add an outer tunneling IPv6 header with required
   extension headers in it.  The processing of IPv6 packets in a DetNet
   Edge node is discussed further in Section 6.4.1
<https://tools.ietf.org/html/draft-ietf-detnet-dp-sol-01#section-6.4.1> .

 

 

With the current spec, a source sends a DetNet packet as

 

                    +---------------------------------+

                    |                                 |

                    |           DetNet Flow           |

                    |             Payload             |

                    |                                 |

                    /---------------------------------\

                    H   Optional DetNet DstOpt Hdr    H

                    \---------------------------------/

                    |          IPv6 header            |

                    |     (with set Flow label)       |

                    +---------------------------------+

 

And then the ingress node needs to re-encapsulate as

 
                    +---------------------------------+
                    |                                 |
                    |           DetNet Flow           |
                    |             Payload             |
                    |                                 |
                    /---------------------------------\
                    H        DetNet DstOpt Hdr        H

                    \---------------------------------/

                    |          IPv6 header            |

                    |     (with set Flow label)       |

                    +=================================+

                    |          Routing header         |
                    /---------------------------------\
                    H        DetNet DstOpt Hdr        H
                    \---------------------------------/
                    |          IPv6 header            |
                    |     (with set Flow label)       |
                    +---------------------------------+

 

This creates a duplication of the DetNet Destination Option.

 

There are alternatives 

 

a)  whereby the packet is tunneled from the source to the detnet ingress,
and based on its state the DetNet ingress accepts the packet, processes it
and then resends it. The tunneled version of this could be:

 

 

                    +---------------------------------+

                    |                                 |

                    |           DetNet Flow           |

                    |             Payload             |

                    |                                 |

                    +---------------------------------+

                    |          IPv6 header            |

                    |   (dest = final destination)    |

                    /=================================\

                    H   Optional DetNet DstOpt Hdr    H

                    \---------------------------------/

                    |          IPv6 header            |

                    |   (dest = DetNet ingress edge)  |

                    |     (with set Flow label)       |

                    +---------------------------------+

 

Which allows the ingress to tunnel to the egress as follows:

 

                    +---------------------------------+

                    |                                 |

                    |           DetNet Flow           |

                    |             Payload             |

                    |                                 |

                    +---------------------------------+

                    |          IPv6 header            |

                    |      (to final destination)     |

                    +=================================+

                    |          Routing header         |
                    /---------------------------------\

                    H   Optional DetNet DstOpt Hdr    H

                    \---------------------------------/

                    |          IPv6 header            |

                    |   (dest = DetNet egress edge)   |

                    |     (with set Flow label)       |

                    +---------------------------------+

 

 

b)  whereby the PREF is done by the end nodes and the tunnel is transport
only, meaning that there are 2 tunnels A and B and that the source sends
twice a packet like this:

 

                    +---------------------------------+

                    |                                 |

                    |           DetNet Flow           |

                    |             Payload             |

                    |                                 |

                    /---------------------------------\

                    H   Optional DetNet DstOpt Hdr    H

                    \---------------------------------/

                    |          IPv6 header            |

                    |   (dest = DetNet ingress edge X)|

                    |     (with set Flow label)       |

                    +---------------------------------+

 

And then the ingress node needs to re-encapsulate as

 
                    +---------------------------------+
                    |                                 |
                    |           DetNet Flow           |
                    |             Payload             |
                    |                                 |
                    /---------------------------------\
                    H        DetNet DstOpt Hdr        H

                    \---------------------------------/

                    |          IPv6 header            |

                    |   (dest = final destination)    |

                    |     (with set Flow label)       |

                    +=================================+

                    |          Routing header         |
                    +---------------------------------+
                    |          IPv6 header            |
                    |   (dest = DetNet egress edge X) |
                    |     (with set Flow label)       |
                    +---------------------------------+

 

Cheers,

 

Pascal