On 5/11/17, 7:31 AM, "William Tu" <u9012...@gmail.com> wrote:
On Wed, May 10, 2017 at 11:04 AM, Darrell Ball <db...@vmware.com> wrote:
> What are the use case(s) of truncate “outside” of sampling/mirroring ?
> The use of truncation in the context of sampling/mirroring is well known.
>
I don't know any other use cases outside sampling/mirroring.
Truncate the current packet, send to a patch port from br-int to
underlay bridge, and forward to a tunnel,
It is important to recognize that a packet “enters the tunnel” at br-int.
seems to be a reasonable way
of using truncate and sampling/mirroring feature.
In order to support remote span cases, it is valid to send a truncated packet
to a tunnel and even multiple tunnel use cases exist.
Sending a truncated tunnel encapsulated packet to another bridge is harder to
mess up although it is still possible. Using a patch port in this context is
one way of
sending the packet to another bridge.
The reason why I brought up the valid use cases of truncation was to
see if we could think about limiting the scope of truncation though some
simple translation checks that make it harder for OVS to process a
corrupted/truncated
packet, after it has already validated it.
Since the valid uses of truncation are limited, I wonder how much effort is
warranted here
and how likely it is to introduce collateral damage.
At the same time, do you think it may be good to have some documentation
updates for
recommended truncation uses and some related warnings ?
William
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