From: dpreed@reed.com
To: "Robert Bradley" <robert.bradley1@gmail.com>
Cc: cerowrt-devel@lists.bufferbloat.net
Subject: Re: [Cerowrt-devel] Fwd: [PATCH] ag71xx: Added support for baby-jumbo packets.
Date: Sat, 23 Jun 2012 15:29:02 -0400 (EDT) [thread overview]
Message-ID: <1340479742.390625935@apps.rackspace.com> (raw)
In-Reply-To: <4FE4D882.50308@gmail.com>
I find it curious that packet aggregation is done in 802.11n standards, but that the packets are limited to 1540. I bet that limit may not be there in all Atheros NICs, and maybe not in this one. Will investigate now that I'm curious.
-----Original Message-----
From: "Robert Bradley" <robert.bradley1@gmail.com>
Sent: Friday, June 22, 2012 4:41pm
To: cerowrt-devel@lists.bufferbloat.net
Subject: Re: [Cerowrt-devel] Fwd: [PATCH] ag71xx: Added support for baby-jumbo packets.
On 22/06/12 21:11, dpreed@reed.com wrote:
> Good step. Why not allow 9K byte jumbos when one's packets traverse a path that is internal to the local area, and all the 1 GigE links support 9K?
>
All the posts I could see claim that the System-on-Chip NIC (Atheros
AR7161) cannot handle packets greater than 1540 octets, so routing 9k
packets from wired->wireless or wired->WAN would not be an option. If I
understood Dave's previous post correctly, though, the built-in switch
allows jumbo packets, so wired->wired internal traffic should work fine
with 9K packets already.
The only issue with that setup is that with mismatched MTUs, it might be
impossible to communicate with the router and the 9k-friendly nodes at
the same time. Thankfully, on Linux at least, you can set per-route
MTUs (http://lartc.org/howto/lartc.cookbook.mtu-discovery.html), so it
might be possible to exploit that to do what you want. Maybe something
like this would work?
ip route add default via 172.30.42.1 mtu 1500
ip route add 172.30.42.1/32 dev eth0 mtu 1500
ip route add 172.30.42.1/27 dev eth0 mtu 9000
--
Robert Bradley
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next prev parent reply other threads:[~2012-06-23 19:29 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAA=Zby5dVYjQNbbwMcHQc7qKSSHnYTAonjRJYG1d6zdqPsZ0Rg@mail.gmail.com>
2012-06-22 19:12 ` Robert Bradley
2012-06-22 20:11 ` dpreed
2012-06-22 20:41 ` Robert Bradley
2012-06-23 19:29 ` dpreed [this message]
2012-06-23 20:10 ` Dave Taht
2012-06-23 21:47 ` Robert Bradley
2012-06-23 22:33 ` dpreed
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