Configure the Desired MTU value

3.11 Configure the Desired MTU value

By default, SDS defines MTU size of all its management and/or signaling networks as 1500 bytes. If the configured virtual network(s) on cloud is VXLAN based and MTU size defined or negotiated on it is 1500 bytes, then accommodate VXLAN header (size 65 bytes) within these 1500 bytes.

Configuring the desired MTU value

This procedure configures the desired MTU value.

Note:

If this procedure fails, contact My Oracle Support (MOS) and ask for assistance.

To verify MTU on SDS system, run the following command:

iqt -pE NetworkDeviceOption

Output:

DeviceOption_ID=0 Keyword=MTU Device_ID=0 Value=1500
DeviceOption_ID=1 Keyword=bootProto Device_ID=0 Value=none
DeviceOption_ID=2 Keyword=onboot Device_ID=0 Value=yes
DeviceOption_ID=3 Keyword=MTU Device_ID=1 Value=1500
DeviceOption_ID=4 Keyword=bootProto Device_ID=1 Value=none
DeviceOption_ID=5 Keyword=onboot Device_ID=1 Value=yes
DeviceOption_ID=6 Keyword=MTU Device_ID=2 Value=1500
DeviceOption_ID=7 Keyword=bootProto Device_ID=2 Value=none
DeviceOption_ID=8 Keyword=onboot Device_ID=2 Value=yes
DeviceOption_ID=9 Keyword=MTU Device_ID=3 Value=1500
DeviceOption_ID=10 Keyword=bootProto Device_ID=3 Value=none
DeviceOption_ID=11 Keyword=onboot Device_ID=3 Value=yes
DeviceOption_ID=12 Keyword=MTU Device_ID=4 Value=1500
DeviceOption_ID=13 Keyword=bootProto Device_ID=4 Value=none
DeviceOption_ID=14 Keyword=onboot Device_ID=4 Value=yes

To change the MTU value on SDS system (optional), run the following command:
For example: If the MTU value is 1500 bytes, to change it to 1435 bytes, run the command:
```
sudo iset -fValue=1435 NetworkDeviceOption where “Keyword='MTU'”
=== changed 256 records ===
```
Wait for few minutes.

To verify the MTU value SDS system, run the command:

ip addr

Output:

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 
inet 127.0.0.1/8 scope host lo 
inet6 ::1/128 scope host 
valid_lft forever preferred_lft forever 
2: control: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1450 qdisc pfifo_fast state UP qlen 1000 
link/ether 02:79:b5:f7:65:0e brd ff:ff:ff:ff:ff:ff 
inet 192.168.1.32/24 brd 192.168.1.255 scope global control 
inet6 fe80::79:b5ff:fef7:650e/64 scope link 
valid_lft forever preferred_lft forever 
3: xmi: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1435 qdisc pfifo_fast state UP qlen 1000 
link/ether 02:90:04:c6:3b:e1 brd ff:ff:ff:ff:ff:ff 
inet 10.75.198.37/25 brd 10.75.198.127 scope global xmi 
inet 10.75.198.4/25 scope global secondary xmi 
inet6 2606:b400:605:b821:90:4ff:fec6:3be1/64 scope global dynamic 
valid_lft 2591870sec preferred_lft 604670sec 
inet6 fe80::90:4ff:fec6:3be1/64 scope link 
valid_lft forever preferred_lft forever 
4: imi: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1435 qdisc pfifo_fast state UP qlen 1000 
link/ether 02:3b:48:96:3c:61 brd ff:ff:ff:ff:ff:ff 
inet 192.168.100.32/24 brd 192.168.100.255 scope global imi 
inet6 fe80::3b:48ff:fe96:3c61/64 scope link 
valid_lft forever preferred_lft forever

To verify on all nodes, run the command:

iqt -pE NetworkDeviceOption

Output:

DeviceOption_ID=0 Keyword=MTU Device_ID=0 Value=1435 
DeviceOption_ID=1 Keyword=bootProto Device_ID=0 Value=none 
DeviceOption_ID=2 Keyword=onboot Device_ID=0 Value=yes 
DeviceOption_ID=3 Keyword=MTU Device_ID=1 Value=1435 
DeviceOption_ID=4 Keyword=bootProto Device_ID=1 Value=none 
DeviceOption_ID=5 Keyword=onboot Device_ID=1 Value=yes 
DeviceOption_ID=6 Keyword=MTU Device_ID=2 Value=1435 
DeviceOption_ID=7 Keyword=bootProto Device_ID=2 Value=none 
DeviceOption_ID=8 Keyword=onboot Device_ID=2 Value=yes 
DeviceOption_ID=9 Keyword=MTU Device_ID=3 Value=1435 
DeviceOption_ID=10 Keyword=bootProto Device_ID=3 Value=none 
DeviceOption_ID=11 Keyword=onboot Device_ID=3 Value=yes 
DeviceOption_ID=12 Keyword=MTU Device_ID=4 Value=1435 
DeviceOption_ID=13 Keyword=bootProto Device_ID=4 Value=none 
DeviceOption_ID=14 Keyword=onboot Device_ID=4 Value=yes