Date: Tue, 6 Dec 2016 11:37:20 -0500 From: Chris Ross <cross+freebsd@distal.com> To: Ryan Stone <rysto32@gmail.com> Cc: freebsd-net <freebsd-net@freebsd.org>, freebsd-pf@freebsd.org Subject: Re: Problems with FreeBSD (amd64 stable/11) router Message-ID: <E80E1A2F-E5CD-4647-8739-3A7F2282938B@distal.com> In-Reply-To: <CAFMmRNz2x4Ns-kE=RpHH8=yb%2BtEDB8ebBkwOmJZGJUHKybyC4w@mail.gmail.com> References: <619F01C2-5A20-4E25-AB0B-4064B598239D@distal.com> <CAFMmRNz-p1804o5fs6g1vbATm5KSRg5fteKgAzg_va3t%2B38%2Bcg@mail.gmail.com> <8C636365-DD9D-4375-9418-D540D8D13C56@distal.com> <CAFMmRNz2x4Ns-kE=RpHH8=yb%2BtEDB8ebBkwOmJZGJUHKybyC4w@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
--Apple-Mail=_EEED0B37-58D1-4216-8357-49C3F65A1E65
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain;
charset=utf-8
> On Dec 6, 2016, at 09:34, Ryan Stone <rysto32@gmail.com> wrote:
>=20
> Let me confirm I understand what's happening:
>=20
> 1) You want to use your router to vlan-tag traffic from your network, =
and then send it out of a lagg over bce interfaces. The bxe interfaces =
have their MTU set to 1500 and the vlan interface to 1496
I believe this is correct. All traffic is using vlan interfaces, =
including the external network connection. But they are all over a lagg =
on two bce=E2=80=99s.
> 2) The TiVo is sending packets with a payload size of 1500 and the DF =
bit set.
>=20
> If this is the case, then the problem is simply that when the packets =
are passed through the vlan interface, the payload of the packets =
exceeds the MTU, but as the DF bit is set, the packets cannot be =
fragmented. Your choices are either to use a 1500 byte MTU on the vlan =
interface (assuming that the network that you are routing to can accept =
1518 byte packets), or only advertise a 1496 byte MTU in your internal =
network.
Perhaps I misunderstood, but I thought that the router should send an =
ICMP in this case (that it cannot fragment the packets due to the DF =
bit), which would then cause the TiVo to send smaller packets. But =
passing that detail for now;
You mention =E2=80=9Conly advertise a 1496 byte MTU in [my] internal =
network.=E2=80=9D I tried doing this by setting an =E2=80=9Cinterface-mtu=
=E2=80=9D option in the DHCP response to the device, but it didn=E2=80=99t=
obey that option. Do you know of another way to =E2=80=9Cadvertise=E2=80=
=9D MTU=E2=80=99s on the internal network?
You also mention using a higher MTU on the network. I hadn=E2=80=99t =
thought of this, but presume it would work. I would only need support =
for that MTU on the bce=E2=80=99s, and in the ethernet switches, =
correct? The ethernet switches I have are Dell PowerConnect 2724 and =
2824 switches, which claim to support jumbo frames. I=E2=80=99ll have =
to find out if I have to _do_ anything to support that, but it should =
work. Thanks for the suggestion, I=E2=80=99ll look into that=E2=80=A6
- Chris
--Apple-Mail=_EEED0B37-58D1-4216-8357-49C3F65A1E65
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
filename=signature.asc
Content-Type: application/pgp-signature;
name=signature.asc
Content-Description: Message signed with OpenPGP using GPGMail
-----BEGIN PGP SIGNATURE-----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=J15r
-----END PGP SIGNATURE-----
--Apple-Mail=_EEED0B37-58D1-4216-8357-49C3F65A1E65--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?E80E1A2F-E5CD-4647-8739-3A7F2282938B>