From: Jakub Kicinski <kuba@kernel.org>
To: "Zekri, Ishay" <Ishay.Zekri@dell.com>
Cc: "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"edumazet@google.com" <edumazet@google.com>,
"Panina, Alexandra" <Alexandra.Panina@dell.com>,
"Barcinski, Bartosz" <Bartosz.Barcinski@dell.com>
Subject: Re: MCVLAN device do not honor smaller mtu than physical device
Date: Wed, 12 Jul 2023 17:24:14 -0700 [thread overview]
Message-ID: <20230712172414.54ef3ca8@kernel.org> (raw)
In-Reply-To: <BN0PR19MB5310720D5344A0EBDFC66D9D9F36A@BN0PR19MB5310.namprd19.prod.outlook.com>
On Wed, 12 Jul 2023 09:06:20 +0000 Zekri, Ishay wrote:
> Hi,
>
> We experiencing an issue in which MACVLAN MTU does not limit the frame size,
> i.e. the limitation is coming from the physical device MTU.
> Kernel version: 5.3.18
>
> As described in the case below:
> https://unix.stackexchange.com/questions/708638/macvlan-device-do-not-honor-smaller-mtu-than-physical-device
>
> it seems like this issue might have a fix.
>
> If there was a known kernel issue that was fixed, I really apricate if you can provide to me the commit in which it was fixed.
In the post above you seem to be pinging the local IP address.
129: K9AT9i1G2x@eth6: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
link/ether ba:c7:36:3f:9a:76 brd ff:ff:ff:ff:ff:ff
inet 192.168.15.40/21 scope global K9AT9i1G2x
^^^^^^^^^^^^^
# ping -c 3 -M do -s 8972 192.168.15.40
^^^^^^^^^^^^^
Local traffic gets routed thru the loopback interface which has
the default MTU of 64k. Did you try to ping something outside
of the host?
next prev parent reply other threads:[~2023-07-13 0:24 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-12 9:06 MCVLAN device do not honor smaller mtu than physical device Zekri, Ishay
2023-07-13 0:24 ` Jakub Kicinski [this message]
2023-07-18 9:01 ` Zekri, Ishay
2023-09-13 15:04 ` Zekri, Ishay
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