I have a Cisco Nexus 3064 that I am using as part of a flat network for the Lab. I have 30 Virtualization Servers(MS HyperV and VMware vSphere) connected to this switch and I want to enable jumbo frames. The Virtualization Servers are able to ping the local VM's using 8K bytes. However I am unable to ping from server to server using 8K bytes. I have configuration (in abbreviation). All the servers are in the same network which I configured as L2 ports with the "switchport" command. However, the interface "MTU" command is unavailable in L2 mode. I am only able to get the interface "MTU" command only in L3 mode with the "no switchport" command on the interface.
# int eth1/2-45
# no switchport
# mtu 9216
# no shut
Is there anything that I am missing? I can ping the servers with less than 1500 bytes, but anything larger fails.
Thank You for any response.
The Cisco Nexus 3000 Series switch does not fragment frames. As a result, the switch cannot have two ports in the same Layer 2 domain with different maximum transmission units (MTUs). A per-physical Ethernet interface MTU is not supported because switch does cut thru switching i.e switch only see the destination mac address and begins to forwarding frame without knowing it has large frame coming in. When you show the interface settings, a default MTU of 1500 is displayed for physical Ethernet interfaces.
Instead, the MTU is set according to the QoS classes. You modify the MTU by setting Class and Policy maps.
You need to define MTU with policy-map type network-qos.
When configuring MTU, follow these guidelines:
Here is the sample.
No. Policy map type network-qos can only go under system-qos. you cannot apply it under any interface.
NX3K01(config-if)# service-policy type ?
qos Qos policy
queuing Queuing policy
NX3K01(config-sys-qos)# service-policy type ?
network-qos Network Qos policy
qos System-level QoS policy
queuing DCE Queuing policy