1. DSR Cloud Installation Guide
  2. Application Configuration
  3. Configure the Desired MTU value

5.4 Configure the Desired MTU value

By default DSR 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/negotiated on it is 1500 bytes, then we need to accommodate VXLAN header (size 65 bytes) within these 1500 bytes.

This procedure configures the desired MTU value.

  1. Verify the MTU on DSR system, by running the following command:
    iqt -pE NetworkDeviceOption
    Sample 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
  2. Change the MTU value on DSR system.
    This is an optional step.
    If the MTU value is 1500 bytes, change it to 1435 bytes, by executing:
    sudo iset -fValue=1435 NetworkDeviceOption where “Keyword='MTU'”
=== changed 256 records ===

    Wait for few minutes.

  3. Verify the MTU value on DSR system by running the following command:
    ip addr
    Sample 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
    Verify on all nodes:
    iqt -pE NetworkDeviceOption
    Sample 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