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List of Ethernet Netcards with Jumbo frame

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In computer networking, jumbo frames are Ethernet frames with more than 1500 bytes of payload, the limit set by the IEEE 802.3 standard.

My router only supports 1500 MTU

--- Code: ---cat /sys/class/net/eth0/mtu
cat /sys/class/net/eth1/mtu
cat /sys/class/net/eth2/mtu

--- End code ---

and refuses any greater value

--- Code: ---echo 1500 >  /sys/class/net/eth0/mtu
echo 2000 >  /sys/class/net/eth0/mtu
write error: Invalid argument
echo 1501 >  /sys/class/net/eth0/mtu
write error: Invalid argument

--- End code ---

but in theory,  some Gigabit Ethernet and even some Fast Ethernet network interface cards might support jumbo frames.

Have you ever seen one?  :-//


--- Code: ---ip link set eth0 mtu 1500

--- End code ---

if you have "iproute2" installed, the above is an alternative command to set the MTU, but it only works if the hardware does support it.


--- Quote from: legacy on September 23, 2019, 08:09:33 am ---Have you ever seen one?  :-//

--- End quote ---

All the time.  But again, I'm pretty heavily involved with data networking for a local ISP, and this is something which happens quite a bit when you get into a service provider network.

But really, most modern interfaces support this.  For instance, I have a little intel NUC for instance which supports it:

--- Code: ---admin:~# ip link set enp3s0 mtu 9000
admin:~# ip link show enp3s0
2: enp3s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9000 qdisc fq_codel state UP mode DEFAULT group default qlen 1000
    link/ether c0:3f:d5:6a:25:98 brd ff:ff:ff:ff:ff:ff
--- End code ---

I also have an Intel 82583V onboard NIC on my windows box, also supports it.

I just logged into my QNAP NAS box, and it supports it as well, 1500 bytes, 4074 bytes, 7418 bytes, or 9000 bytes.

Which brings up another point,   Some devices only support *certain* sized giant frames.   For some, you're going to have to find the size it supports, I'd try at least the ones I just mentioned.  If you know the brand/type of the interface in  your router, you might find that it doesn't support 1501, but it does support something larger.

but, even 100Mbps cards do support jumbos ?

Enabling some verbose in the kernel module of the netcard, it says which is the max

--- Code: ---eth0: Invalid MTU 9000 requested, hw max 1500
ip: SIOCSIFMTU: Invalid argument

eth0: Invalid MTU 7000 requested, hw max 1500
ip: SIOCSIFMTU: Invalid argument

eth0: Invalid MTU 4000 requested, hw max 1500
ip: SIOCSIFMTU: Invalid argument

eth0: Invalid MTU 2000 requested, hw max 1500
ip: SIOCSIFMTU: Invalid argument

--- End code ---

I am going to try { 2000, 4000, 7000, 9000 } MTU on other routers/computers/servers. Including Ubiquiti RSP and alike.

I doubt it's popular in 100Mb ones. Where are you getting 1G cards that don't support it, though? ;)

--- Code: ---05:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 06)

11:14:34.673396 IP > ICMP echo request, id 2877, seq 4, length 8008
11:14:34.673421 IP > ICMP echo reply, id 2877, seq 4, length 8008
--- End code ---


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