Hi Chris,
On 11-02-04 05:14 PM, Christopher Morrow wrote:
On Fri, Feb 4, 2011 at 10:27 AM, Christopher Morrow
<christopher.mor...@gmail.com> wrote:
On Fri, Feb 4, 2011 at 7:21 AM, Roland Bless <roland.bl...@kit.edu> wrote:
Hi,
Christopher Morrow wrote:
My feeling is this:
hop-by-hop processing will happen in slow-path (if you permit it to
happen at all), you can't build a router today with an asic that'll
know how to handle options which are created in the future :(
while the latter is surely true, I don't think that this
argument precludes to implement fast path processing
of at least _some_ HbH options. I think that the current
implemented strategy to simply pass all HbH options
to the slow path CPU is broken.
I'm not sure whether it is feasible, but couldn't the
Fast Path (ASIC) at least check for:
- known options to be processed in the fast path, e.g.,
some CONEX info field
which options? how often would you expect this list to update? routers
live in the network for ~7 years or so, in large networks. ASIC
updates mean very expensive (equipment, personnel, sla) changes are
required.
Someone reminded me off-list to be clear about what the problem is...
Any packet that requires hop-by-hop behavior is a problem. If a
backbone router has to attempt to stream packets off a production
interface and into the RE/RP/PRP, the router will fall over.
I fully agree with you.
So, the operator(s) are left with 2 real options:
1) drop all packets NOT icmpv6, tcp, udp (drop all other extension headers)
2) ignore any extension header NOT icmpv6, udp, tcp
It would be grand if router vendors (Juniper, Cisco, Force10, Extreme,
Foundry, Huawei, etc) would provide a knob on all of their platforms
that said:
hbh-options [ignore|drop]
The ignore option was what I proposed in Section 3.2 of
http://tools.ietf.org/html/draft-krishnan-ipv6-hopbyhop-05
but dropping should be something that an operator should be able to
enable as well.
Cheers
Suresh
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