What are the network maximum transmission unit (MTU) requirements for PCoIP?

Rate this Article
Average: 1 (1 vote)

PCoIP maximum transmission unit (MTU) Requirements

Every network has a MTU that dictates the maximum size a individual network packet can be for transmission. If the packet is larger than the MTU it will be fragmented and sent as multiple packets or dropped if the do not fragment flag is set. The MTU is set on each network segment and can be different on each network between the PCoIP host and client. Typically on Ethernet the MTU is 1500 but on an ADSL connection it maybe 1492. PCoIP has a requirement that packets cannot be fragmented. At the start of each PCoIP session, the MTU is negotiated between the PCoIP host and PCoIP client by using the MTU setting configured on each end to determine the lower of the two. This value sets the maximum PCoIP packet size for the PCoIP session. The MTU that PCoIP is using, must be lower or equal to the lowest MTU of any network segment between the PCoIP client and PCoIP host. The smallest supported MTU value is 500 and the largest is 1500.


PCoIP MTU defaults

The default MTU size of 1200 bytes for PCoIP sessions has generally be found suitable for most environment. Although it's a configurable setting, you usually do not have to change the MTU size. A typical Ethernet MTU size is 1500. PCoIP sessions have a lower default MTU to allow for additional encapsulation data to be added to the packet by network devices in the network path. There maybe scenarios where the MTU needs to be adjusted such as when using a VPN as they can limit MTU size because they append packet headers to all packets traversing the VPN tunnel. In high performance scenarios the MTU maybe more desirable at 1500 to reduce the number of packets the network needs to process under high load.


PCoIP client and PCoIP host negotiated MTU value


PCoIP Zero Client Firmware 4.5.0 and prior
(1400 MTU Default)

PCoIP Zero Client Firmware 4.5.1 and later
(1200 MTU Default)

PCoIP Software Client
(1200 MTU Default)
PCoIP Mobile Client
(1200 MTU Default)

PCoIP Remote Workstation Card firmware 4.5.0 and prior

(1400 MTU Default)
1400 1200 1200 1200

PCoIP Remote Workstation Card firmware 4.5.0 and later
(1200 MTU Default)

1200 1200 1200 1200
VMware View 5
(1300 MTU Default)
1300 1200 1200 1200

VMware View 6 and later
(1200 MTU Default)

1200 1200 1200 1200

PCoIP Agent
(1200 MTU Default)

1200 1200 1200 1200


Testing the maximum MTU

When adjusting the MTU, ensure all network segments the packet will traverse will accept a packet of that size. You can use the ping command to test the path. Use the -f switch to set the don't fragment flag and -l switch to set the size. To send a test packet of 1450 bytes use this command.

If you get a response the packet successfully traversed the network. If you receive "Packet needs to be fragmented but DF set." then the packet was too large. Try again with a lower MTU value.


Configuring the MTU

When configuring the MTU remember that the lower of the PCoIP host and PCoIP client value will be the PCoIP Session value.

If the MTU will be increased above the default value, ensure both the PCoIP client and PCoIP host are configured to the new MTU.

If the MTU only needs to be lower at one network site or for a particular network use, you may choose to set the MTU on the PCoIP client only.

For information on configuring the MTU on PCoIP clients, consult the Administrators' guide for the product and release.

PCoIP Agents maybe configuring using the PCoIP GPO.

See also:

How to configure the PCoIP MTU Size variable