Re: [Softwires] IPv6 VPNs configured over 1280 MTU tunnels

FYI, here's my tunnel MTU guy that I showed back during
the Vancouver meeting (December 2007)? I think he is
still left with the same conundrum today that he was
back then...

Fred
fred.l.templin@boeing.com

> -----Original Message-----
> From: softwires-bounces@ietf.org 
> [mailto:softwires-bounces@ietf.org] On Behalf Of Templin, Fred L
> Sent: Friday, October 08, 2010 10:18 AM
> To: Softwires; v4tov6transition@ietf.org
> Subject: [Softwires] IPv6 VPNs configured over 1280 MTU tunnels
> 
> End systems in end user networks that connect to the
> IPv6 Internet will likely want to configure IPv6 VPNs,
> e.g., so that they can securely connect to their home
> office networks. Those VPN links must present a 1280
> minimum MTU to upper layers, but if they traverse a
> link in the path with a too-small MTU then the end
> system will see an MTU underrun and will need to use
> IPv6 fragmentation.
> 
> An IPv6-in-IPv4 tunnel with a fixed static 1280 MTU is
> an example of a link in the path that could cause such
> an MTU underrun for end system VPN links. So, should we
> be concerned that tunnels with a fixed 1280 MTU would
> make life difficult for the common operational practice
> of end systems using VPNs?
> 
> Thanks - Fred
> fred.l.templin@boeing.com   
> 
> > -----Original Message-----
> > From: v4tov6transition-bounces@ietf.org 
> > [mailto:v4tov6transition-bounces@ietf.org] On Behalf Of 
> > Templin, Fred L
> > Sent: Friday, October 08, 2010 7:52 AM
> > To: Yiu L. Lee; Brian E Carpenter; Ole Troan
> > Cc: Softwires; v4tov6transition@ietf.org
> > Subject: Re: [v4tov6transition] [Softwires] ISP support of 
> > NativeIPv6across NAT44 CPEs -Proposed 6a44 Specification
> > 
> >  
> > > CPE. This double tunneling tech seems scary.
> > 
> > More to this point about double-tunneling, how were
> > folks thinking that IPv6 VPNs would be run over a
> > 1280 MTU IPv6-in-IPv4 tunnel? That is double-tunneling,
> > and seems like it would be a quite common case, but the
> > MTU seems deficient. Should it use IPv6 fragmentation?
> > 
> > Fred
> > fred.l.templin@boeing.com
> > _______________________________________________
> > v4tov6transition mailing list
> > v4tov6transition@ietf.org
> > https://www.ietf.org/mailman/listinfo/v4tov6transition
> > 
> _______________________________________________
> Softwires mailing list
> Softwires@ietf.org
> https://www.ietf.org/mailman/listinfo/softwires
> 

Re: [Softwires] IPv6 VPNs configured over 1280 MTU tunnels

Attachment: Tunnel-MTU.pdf