From: Stephen Hemminger <stephen@networkplumber.org>
To: Rajasekhar Pulluru <pullururajasekhar@gmail.com>
Cc: dev@dpdk.org
Subject: Re: Restrict max packet size on rx
Date: Fri, 18 Oct 2024 10:37:16 -0700 [thread overview]
Message-ID: <20241018103716.46b23a63@hermes.local> (raw)
In-Reply-To: <CAGA5_H7a2D8SHUGhVZYKj_T9siRVMpxwJCSNS3fVZa3RMOzx0g@mail.gmail.com>
On Fri, 18 Oct 2024 22:19:35 +0530
Rajasekhar Pulluru <pullururajasekhar@gmail.com> wrote:
> Thanks Stephen.
>
> On Fri, Oct 18, 2024 at 10:13 PM Stephen Hemminger <
> stephen@networkplumber.org> wrote:
>
> > On Fri, 18 Oct 2024 22:05:24 +0530
> > Rajasekhar Pulluru <pullururajasekhar@gmail.com> wrote:
> >
> > > Team,
> > > Does setting mtu using rte_eth_dev_set_mtu limit the maximum size of the
> > > packet received on the dpdk port to the configured mtu size?
> > >
> > > On an intel machine with ixgbe port, with mtu set to 1500, no rx-offloads
> > > enabled, ixgbe dpdk port is able to receive packets greater than 1500
> > size
> > > and even jumbo frames of size 9000, even though the peer is sending them
> > > fragmented with mtu of 1500.
> > >
> > > How do I restrict the port not to receive any frame greater than mtu
> > size?
> > >
> > > Appreciate any help,
> > > Thanks.
> > > Rajasekhar
> >
> >
> > In networking, MTU and MRU are overlapping concepts.
> > The MTU value is used as a hint to the driver as to what size buffer to
> > allocate
> > but it can use larger if it wants. If you have restrictions, then the
> > application
> > needs to enforce them.
> >
There are some drivers like ixgbe that need to round up the receive buffer to
a power of 2. So it is possible to get 2K frames even with standard 1500 byte MTU.
prev parent reply other threads:[~2024-10-18 17:37 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-18 16:35 Rajasekhar Pulluru
2024-10-18 16:43 ` Stephen Hemminger
2024-10-18 16:49 ` Rajasekhar Pulluru
2024-10-18 17:37 ` Stephen Hemminger [this message]
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