Subject: OMNI interface - MTU

From: "Templin (US), Fred L" <[email-masked]>
Date: Tue, 18 Feb 2020 16:50:02 +0000

Like any IPv6 interface, the OMNI interface must configure a Maximum Transmission Unit (MTU)
that provides the IPv6 layer with a maximum size that the interface can transport as a single unit.
The OMNI spec mandates that the OMNI interface MTU is 9180 bytes (see: RFC2492) but this
means that the interface must be adaptive in its dealings with underlying interfaces that may
have different MTU sizes. For example, if the OMNI interface is configured over three underlying
interfaces with MTUs 1280, 1500 and 9000 the OMNI interface needs to decide what to do when
a large packet (e.g., 4096 byes) arrives. For the 9000 interface, the OMNI interface can just send
the packet out according to the native underlying interface frame format. For the 1280 and 1500
interfaces, however, the OMNI interface has two options: 1) drop and return a Packet Too Big,
or 2) Encapsulate using link-layer encapsulation per RFC2473 and employ IPv6 fragmentation
and reassembly. Both approaches will provide correct behavior, but 1) maybe more prone to
dropping packets and returning PTB, while 2) may provide improved performance at the
expense of including additional code. Please bring any discussion points regarding the OMNI
interface MTU under this thread.

Fred

> -----Original Message-----
> From: ipv6 [mailto:[email-masked]] On Behalf Of Templin (US), Fred L
> Sent: Tuesday, February 18, 2020 8:07 AM
> To: [email-masked]; [email-masked]
> Subject: FW: I-D Action: draft-templin-6man-omni-interface-00.txt
> 
> 6man and atn list members,
> 
> We have received direction to rename the OMNI interface draft to more closely match the
> document title and to indicate the target working group. This submission therefore replaces
> the former draft name thread, and should be used as the basis for further discussion.
> 
> The OMNI interface spec introduces many important constructs that would be very difficult
> to track in a single discussion thread. I will initiate multiple sub-threads to invite discussion
> on specific aspects of the document in subsequent messages.
> 
> Thanks - Fred
> 
> -----Original Message-----
> From: I-D-Announce [mailto:[email-masked]] On Behalf Of [email-masked]
> Sent: Tuesday, February 18, 2020 7:35 AM
> To: [email-masked]
> Subject: I-D Action: draft-templin-6man-omni-interface-00.txt
> 
> 
> A New Internet-Draft is available from the on-line Internet-Drafts directories.
> 
> 
>         Title           : Transmission of IPv6 Packets over Overlay Multilink Network (OMNI) Interfaces
>         Authors         : Fred L. Templin
>                           Tony Whyman
> 	Filename        : draft-templin-6man-omni-interface-00.txt
> 	Pages           : 36
> 	Date            : 2020-02-18
> 
> Abstract:
>    Mobile nodes (e.g., aircraft of various configurations, terrestrial
>    vehicles, seagoing vessels, mobile enterprise devices, etc.)
>    communicate with networked correspondents over multiple access
>    network data links and configure mobile routers to connect end user
>    networks.  A multilink interface specification is therefore needed
>    for coordination with the network-based mobility service.  This
>    document specifies the transmission of IPv6 packets over Overlay
>    Multilink Network (OMNI) Interfaces.
> 
> 
> The IETF datatracker status page for this draft is:
> https://datatracker.ietf.org/doc/draft-templin-6man-omni-interface/
> 
> There are also htmlized versions available at:
> https://tools.ietf.org/html/draft-templin-6man-omni-interface-00
> https://datatracker.ietf.org/doc/html/draft-templin-6man-omni-interface-00
> 
> 
> Please note that it may take a couple of minutes from the time of submission
> until the htmlized version and diff are available at tools.ietf.org.
> 
> Internet-Drafts are also available by anonymous FTP at:
> ftp://ftp.ietf.org/internet-drafts/
> 
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