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.
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:
For the Cisco Nexus 3000 Series switch , the MTU is controlled by the value configured on the class-default. The same MTU must be configured on all classes.
Enter the system jumbomtu command to define the upper bound of any MTU in the system. The system jumbo MTU has a default value of 9216 bytes. The minimum MTU is 1500 bytes and the maximum MTU is 9216 bytes.
The system class MTU sets the MTU for all packets in the class. The system class MTU cannot be configured larger than the global jumbo MTU.
The default system class has a default MTU of 1500 bytes. You can configure this value.
The switch sends the MTU configuration to network adapters that support DCBX.
This is actually a pretty cool feature, i didn't even know it existed until I was looking for a solution to advertise a subnet (prefix in BGP talk), only if a certain condition existed. This is exactly what conditional advertisements does
j ai une question j ai achete un routeur cisco 887VA-k9 , je le configuré avec la configuration ci- dessous
si je le lier avec mon pc portable sur l un de ses ports directement ça marche toute est bien ( la connexion internet + m...
Attached policy provides CLI access to the Cisco 4G router over text messaging. Two files are in the attached .tar file:
2. PDF with instructions on how to load and use the .tcl file.