How do i change MTU for Appneta's Usage Interfaces

Products

• AppNeta

Issue/Introduction

Our monitoring points are connected to our switch's SPAN/Mirror port.   We have would like to adjust the MTU of the Usage interface in the event data of a larger packet size is sent then the default 1500.

Resolution

For Usage monitoring, MTU settings may needed to be adjusting in order to receive packets >1500 bytes.  In order to perform the change, 

1.  SSH into monitoring point

2.  For Monitoring points such as the M50,  Edit the bridge used by the Usage Interface.

For example, you can use:
vi /etc/network/interfaces.d/bridge0 

3.  Edit the bridge by adding the last line:

auto bridge0
iface bridge0 inet static
   address 0.0.0.0
   netmask 0.0.0.0
   bridge_stp off
   bridge_maxwait 0
   bridge_ports eth2 eth3
   pre-down /opt/pathview/scripts/bypass-control.sh 0 bypass
   post-up ifconfig eth2 mtu 1600 && ifconfig eth3 mtu 1600

4.  Save the settings, they restart networking:

systemctl restart networking.service

5.  You can verify the settings using the ifconfig command:

• ifconfig
  bridge0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1600
          ether a2:d0:xx:xx:xx:xx  txqueuelen 1000  (Ethernet)
          RX packets 106905  bytes 164988751 (157.3 MiB)
          RX errors 0  dropped 0  overruns 0  frame 0
          TX packets 106905  bytes 164988751 (157.3 MiB)
          TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
  
  docker0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
          inet 172.16.0.1  netmask 255.255.255.252  broadcast 172.16.0.3
          ether ether a2:d0:xx:xx:xx:xx  txqueuelen 0  (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
  
  eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
          inet 10.11.12.13  netmask 255.255.255.0  broadcast 10.11.12.255
          ether ether a2:d0:xx:xx:xx:xx  txqueuelen 1000  (Ethernet)
          RX packets 4794  bytes 458552 (447.8 KiB)
          RX errors 0  dropped 43  overruns 0  frame 0
          TX packets 896  bytes 233189 (227.7 KiB)
          TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
  
  eth2: flags=4419<UP,BROADCAST,RUNNING,PROMISC,MULTICAST>  mtu 1600
          ether ether a2:d0:xx:xx:xx:xx  txqueuelen 1000  (Ethernet)
          RX packets 106905  bytes 166485421 (158.7 MiB)
          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
  
  eth3: flags=4419<UP,BROADCAST,RUNNING,PROMISC,MULTICAST>  mtu 1600
          ether ether a2:d0:xx:xx:xx:xx  txqueuelen 1000  (Ethernet)
          RX packets 0  bytes 0 (0.0 B)
          RX errors 0  dropped 0  overruns 0  frame 0
          TX packets 106905  bytes 166485421 (158.7 MiB)
          TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

Additional Information

Also have a look at running a packet capture on the appliance:

https://knowledge.broadcom.com/external/article?articleNumber=280758