How to enable jumbo frames

SUMMARY

Steps needed to enable jumbo frames on appliances

ISSUE

Client wants to enable jumbo frames on eth1

eth1      Link encap:Ethernet  HWaddr AB:CD:EF:01:23:45
          inet addr:192.168.9.240  Bcast:192.168.9.255  Mask:255.255.255.0
          inet6 addr: fe80::ae1f:6bff:fe40:ed5c/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1597659 errors:0 dropped:0 overruns:0 frame:0
          TX packets:294545 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:1838042722 (1.7 GiB)  TX bytes:76402917 (72.8 MiB)

RESOLUTION

NOTE: In the example below, we will be editing values for ETH1

You will need to add the line item MTU=9000 to the appropriate ifcfg-eth file located at /etc/sysconfig/network-scripts, and ensure the ONBOOT value is yes
 

TASKS

  1. Execute this command:  vi /etc/sysconfig/network-scripts/ifcfg-eth1
DEVICE=eth0
TYPE=Ethernet
ONBOOT=yes
NM_CONTROLLED=yes
BOOTPROTO=none
GATEWAY=192.168.9.1
NETMASK=255.255.255.0
IPADDR=192.168.9.240
METRIC=0
  1. Add the line MTU=9000 (below TYPE=Ethernet is fine) and set the ONBOOT=yes
DEVICE=eth0
TYPE=Ethernet
MTU=9000
ONBOOT=yes
NM_CONTROLLED=yes
BOOTPROTO=none
GATEWAY=192.168.9.1
NETMASK=255.255.255.0
IPADDR=192.168.9.240
METRIC=0
  1. Now restart the network services by issuing this command: service network restart
  2. Execute this command to show the interfaces: ifconfig
  3. If you do not see the interface eth1, execute this command to start it: ifup eth1
  4. Check the status of the interfaces again: ifconfig
  5. Successful output should look like:
eth1      Link encap:Ethernet  HWaddr AB:CD:EF:01:23:45
          inet addr:192.168.9.240  Bcast:192.168.9.255  Mask:255.255.255.0
          inet6 addr: fe80::ae1f:6bff:fe40:ed5c/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:9000  Metric:1
          RX packets:1597659 errors:0 dropped:0 overruns:0 frame:0
          TX packets:294545 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:1838042722 (1.7 GiB)  TX bytes:76402917 (72.8 MiB)

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