Jumbo Frames on Ubuntu

November 13, 2023 James Higley Linux, Technology 0
jug ears, elephant, dumbo-304819.jpg

Yo, you said JUMBO not DUMBO. Right, I get it, the picture of Dumbo may help us with jumbo frames, I’ll explain.

For now – here’s how to enable jumbo frames, or MTU: 9000

First, let’s look at the network on our ubuntu box, I like to to use ‘ip addr’ or ‘ifconfig -a’. Run them both, you’ll see the difference.

ip addr – this is the default network tool out of the box

root@a02-30:~# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eno33np0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9000 qdisc mq state UP group default qlen 1000
    link/ether bc:97:e1:7e:96:10 brd ff:ff:ff:ff:ff:ff
    inet6 fe80::be97:e1ff:fe7e:9610/64 scope link
       valid_lft forever preferred_lft forever
3: eno34np1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9000 qdisc mq state UP group default qlen 1000
    link/ether bc:97:e1:7e:96:11 brd ff:ff:ff:ff:ff:ff
    inet6 fe80::be97:e1ff:fe7e:9611/64 scope link
       valid_lft forever preferred_lft forever
4: idrac: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether 70:b5:e8:db:3e:c7 brd ff:ff:ff:ff:ff:ff
5: eno34np1.617@eno34np1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9000 qdisc noqueue state UP group default qlen 1000
    link/ether bc:97:e1:7e:96:11 brd ff:ff:ff:ff:ff:ff
    inet 10.6.17.13/24 brd 10.6.17.255 scope global eno34np1.617
       valid_lft forever preferred_lft forever
    inet6 fe80::be97:e1ff:fe7e:9611/64 scope link
       valid_lft forever preferred_lft forever
6: eno33np0.3517@eno33np0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether bc:97:e1:7e:96:10 brd ff:ff:ff:ff:ff:ff
    inet 10.23.17.13/24 brd 10.23.17.255 scope global eno33np0.3517
       valid_lft forever preferred_lft forever
    inet6 fe80::be97:e1ff:fe7e:9610/64 scope link
       valid_lft forever preferred_lft forever
7: eno33np0.517@eno33np0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9000 qdisc noqueue state UP group default qlen 1000
    link/ether bc:97:e1:7e:96:10 brd ff:ff:ff:ff:ff:ff
    inet 10.5.17.13/24 brd 10.5.17.255 scope global eno33np0.517
       valid_lft forever preferred_lft forever
    inet6 fe80::be97:e1ff:fe7e:9610/64 scope link
       valid_lft forever preferred_lft forever

ifconfig -a – this is a cleaner output, you do have to ‘apt install net-tools’

root@a02-30:~# ifconfig -a
eno33np0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 9000
        inet6 fe80::be97:e1ff:fe7e:9610  prefixlen 64  scopeid 0x20<link>
        ether bc:97:e1:7e:96:10  txqueuelen 1000  (Ethernet)
        RX packets 56171152  bytes 77973318452 (77.9 GB)
        RX errors 0  dropped 0  overruns 0  frame 160
        TX packets 21027012  bytes 19108318404 (19.1 GB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

eno33np0.517: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 9000
        inet 10.5.17.13  netmask 255.255.255.0  broadcast 10.5.17.255
        inet6 fe80::be97:e1ff:fe7e:9610  prefixlen 64  scopeid 0x20<link>
        ether bc:97:e1:7e:96:10  txqueuelen 1000  (Ethernet)
        RX packets 12521317  bytes 74591920428 (74.5 GB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 14787228  bytes 18610704680 (18.6 GB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

eno33np0.3517: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 10.23.17.13  netmask 255.255.255.0  broadcast 10.23.17.255
        inet6 fe80::be97:e1ff:fe7e:9610  prefixlen 64  scopeid 0x20<link>
        ether bc:97:e1:7e:96:10  txqueuelen 1000  (Ethernet)
        RX packets 333386  bytes 103723870 (103.7 MB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 36374  bytes 5076924 (5.0 MB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

eno34np1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 9000
        inet6 fe80::be97:e1ff:fe7e:9611  prefixlen 64  scopeid 0x20<link>
        ether bc:97:e1:7e:96:11  txqueuelen 1000  (Ethernet)
        RX packets 58765365  bytes 81599580796 (81.5 GB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 21618292  bytes 19173729660 (19.1 GB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

eno34np1.617: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 9000
        inet 10.6.17.13  netmask 255.255.255.0  broadcast 10.6.17.255
        inet6 fe80::be97:e1ff:fe7e:9611  prefixlen 64  scopeid 0x20<link>
        ether bc:97:e1:7e:96:11  txqueuelen 1000  (Ethernet)
        RX packets 13006087  bytes 78149993698 (78.1 GB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 15305822  bytes 18671476988 (18.6 GB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

idrac: flags=4098<BROADCAST,MULTICAST>  mtu 1500
        ether 70:b5:e8:db:3e:c7  txqueuelen 1000  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 456  bytes 44466 (44.4 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 456  bytes 44466 (44.4 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

We will be modifying vlan 517 and changing it back to MTU 1500

  • eno33np0.517@eno33np0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9000 qdisc noqueue state UP group default qlen 1000

First we need to change the MTU for the base ethernet adapter for van 517, eno33np0.

sudo ip link set mtu 1500 eno33np0

Now we can change the MTU for vlan 517, eno33np0.517

sudo ip link set mtu 1500 eno33np0.517

These changes take place immediately. 

eno33np0.517@eno33np0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000

…to be continued, I’ll update on how to add this change permanently. Stay tuned…

About James Higley 7 Articles
James “higs” Higley is a Systems Engineer at Pure Storage [TECHNOLOGY]. Often out side of work, you can find James hanging out with his family and friends. [LIFE]
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