[openstack-dev] [TripleO][Neutron] PMTUd broken in gre networks
robertc at robertcollins.net
Thu Jan 23 20:41:41 UTC 2014
I'll set some time aside next week to drill into that. I certainly
don't recall seeing any utilization issues when I was first
On 24 January 2014 07:26, Salvatore Orlando <sorlando at nicira.com> wrote:
> My expertise on the subject is pretty much zero, but the performance loss
> (which I think is throughput loss) is so blatant that perhaps there's more
> than the MTU issue. From what Robert writes, GRO definitely plays a role
> My only suggestion would be to route the question to ovs-discuss in order to
> get some help in precisely understanding what's going on.
> In order to understand the relationship with GRO, what are the CPU usage
> levels on the receiving node with and without GRO enabled?
> On 22 January 2014 17:26, Rick Jones <rick.jones2 at hp.com> wrote:
>> On 01/22/2014 03:01 AM, Robert Collins wrote:
>>> I certainly think having the MTU set to the right value is important.
>>> I wonder if there's a standard way we can signal the MTU (e.g. in the
>>> virtio interface) other than DHCP. Not because DHCP is bad, but
>>> because that would work with statically injected network configs as
>> Can LLDP be used here somehow? It might require "stretching" things a
>> bit - not all LLDP agents seem to include the information, and it might
>> require some sort of "cascade." It would also require the VM to pay
>> attention to the frames as they arrive, but in broad, hand-waving, blue-sky
>> theory it could communicate maximum frame size information within the
>> broadcast domain.
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Robert Collins <rbtcollins at hp.com>
HP Converged Cloud
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