RV: (ipv6mh) hardware support for extension headers

["marcelo bagnulo" <mbagnulo@ing.uc3m.es>]

Erik, Jordi,

This is a message where Tony Hain explained why it is difficult to support
new extension headers in all packets,
This message was sent to ipv6mh list a while ago...
Hope this helps to explain Jordi's concerns.
Regards, marcelo

> -----Mensaje original-----
> De: Tony Hain [mailto:alh-ietf@tndh.net]
> Enviado el: miércoles, 27 de noviembre de 2002 1:59
> Para: 'marcelo bagnulo'; 'Michel Py'; 'Ole Troan'
> CC: 'Jordi Palet Martinez'; 'ipv6mh'; 'Vladimir Ksinant'; 'Yoshifumi
> Atarashi'; 'Suzuki Shinsuke'; 'Kazuaki Tsuchiya'; 'Elwyn Daview'
> Asunto: RE: (ipv6mh) hardware support for extension headers
>
>
> Marcelo,
>
> The basic problem is that network operators have been told that the
> proper thing to do is filter on the L4 port. This means that all
> hardware implementations that are expected to be deployed on a network
> boundary have to be able to parse the L4 port. Since everyone has a
> different definition of what router class is needed at a boundary, this
> effectively means all routers have to support finding the L4 port in
> hardware. This is required even though most of the deployed routers
> never look at the extension headers or the L4 port. The result is that
> any new extension header that will be carried along with the current
> common set, will cause packets to drop off the fast path. Yes, border
> specific routers could be developed, but the market for them would be so
> small, and the extra hardware necessary would be so much greater that
> the result would be so expensive that nobody would ever buy them.
>
> Tony
>
>
> > -----Original Message-----
> > From: marcelo bagnulo [mailto:marcelo@it.uc3m.es]
> > Sent: Monday, November 25, 2002 1:04 PM
> > To: Michel Py; Ole Troan
> > Cc: Jordi Palet Martinez; ipv6mh; Vladimir Ksinant; Yoshifumi
> > Atarashi; Suzuki Shinsuke; Kazuaki Tsuchiya; Elwyn Daview
> > Subject: RE: (ipv6mh) hardware support for extension headers
> >
> >
> > Michel,
> >
> > if you don´t mind, i would split the question in two:
> >
> > - How would you rate the changes needed in routers in order
> > to forward packets carrying the extesnion header WITHOUT
> > PORCESSING it?
> >
> > - How would you rate the changes needed in routers in order
> > to forward packets carrying the extesnion header and also
> > process the extension header?
> >
> > Note that most routers will only forward packets containing
> > the extesnion header without processing it.
> >
> > Thanks, marcelo
> >
> > > -----Mensaje original-----
> > > De: Michel Py [mailto:michel@arneill-py.sacramento.ca.us]
> > > Enviado el: domingo, 24 de noviembre de 2002 23:48
> > > Para: Ole Troan
> > > CC: Marcelo Bagnulo; Jordi Palet Martinez; ipv6mh; Vladimir
> > Ksinant;
> > > Yoshifumi Atarashi; Suzuki Shinsuke; Kazuaki Tsuchiya; Elwyn Daview
> > > Asunto: RE: (ipv6mh) hardware support for extension headers
> > >
> > >
> > > > Ole Troan wrote:
> > > > the more serious issue with Marcelo's draft is that
> > todays routers
> > > > aren't built to send ICMP errors (or forward the packet
> > in Marcelo's
> > > > case), for every packet to an unknown destination.
> > >
> > > Dumb question for all router vendors:
> > > Assuming that all political hurdles have been cleared, if
> > you had to
> > > implement (in silicon, for those of who that have hardware-assisted
> > > routers) what Marcelo's draft requires, how would you rate
> > the work it
> > > would take?
> > >
> > > a) Piece of cake, just needs to be decided and would be in the next
> > > version of the chips.
> > > b) About the same as any other extension header.
> > > c) Much more difficult than other extension headers you
> > already have
> > > implemented.
> > >
> > > Thanks
> > > Michel.
> > >
> > >
> >
>