Experiences with IPv6 and Routing Efficiency

Nick Hilliard nick at foobar.org
Sun Jan 19 16:11:07 UTC 2014

On 19/01/2014 04:00, Mukom Akong T. wrote:
> Have you found them to be more troublesome to process than IPv4 options
> are/were?

The problem is that you can have long EH chains, with one after another.
Generally speaking, most hardware forwarding engines will perform a lookup
based on the first N bytes of a packet.

If arbitrary length EHs are not supported by the hardware, then you have 3
options: forward the packets unilaterally, drop the packets unilaterally or
punt to a cpu/npu.  Punting and forwarding both open up denial of service
attacks for hardware-forwarded routers, so generally the only sensible
option is to drop packets with long EH chains.


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