Home » Cisco » 350-080 » Enabling jumbo frame support on a Cisco Nexus 5500 Switch can be done through which method?
Enabling jumbo frame support on a Cisco Nexus 5500 Switch can be done through which method?
A. Changing the default policy map from a default MTU of 1500 to 9216
B. Using the command system jumbomtu 9216
C. Using the command interface MTU 9216
D. Configuring the default Ethernet system class to an MTU of 9216 with a new network QoS policy map
Correct Answer: D
Explanation/Reference:
Explanation:
The Cisco Nexus device is a Layer 2 switch, and it does not support packet fragmentation. A maximum transmission unit (MTU) configuration mismatch between ingress and egress interfaces may result in packets being truncated.
When configuring MTU, follow these guidelines:
MTU is specified per system class. The system class allows a different MTU for each class of traffic but they must be consistent on all ports across the entire switch. You cannot configure MTU on the interfaces.
Fibre Channel and FcoE payload MTU is 2158 bytes across the switch. As a result, the rxbufsize for Fibre Channel interfaces is fixed at 2158 bytes. If the Cisco Nexus device receives an rxbufsize from a peer that is different than 2158 bytes, it will fail the exchange of link parameters (ELP) negotiation and not bring the link up.
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 2158 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 FcoE system class (for Fibre Channel and FcoE traffic) has a default MTU of 2158 bytes. This value cannot be modified.
The switch sends the MTU configuration to network adapters that support DCBX.
Reference: http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5500/sw/qos/6x/b_5500_QoS_Config_6x/ b_5500_QoS_Config_602N12_chapter_0110.html (see ‘MTU’)