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Updated:November 23, 2022
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This document describes issues caused when you configure a Jumbo Maximum Trnsmission Unit (MTU) packet in a Nexus 5000 Series Switch.
There are no specific requirements for this document.
The information in this document is based on these series of Nexus switches:
NX-OS version 4.1(3)N2(1a)
The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, ensure that you understand the potential impact of any command.
This document describes the issues that arise when you need to use Jumbo Packet in a Nexus 5000 Series Switch. The scenario described can occur when you try to transfer jumbo packets between Nexus 5000 and/or Nexus 7000 switches.
The packet loss can happen between two Nexus 5000 switches or between a Nexus 5000 switch and Nexus 7000 switch.
When you ping a host with the packet size of 9216 bytes, you can see packet loss of 50 percent.
Nexus-5000#ping 172.16.0.1 packet-size 9216 count 20
PING 172.16.0.1 (172.16.0.1): 9216 data bytes
9224 bytes from 172.16.0.1: icmp_seq=0 ttl=254 time=6.094 ms
Request 1 timed out
9224 bytes from 172.16.0.1: icmp_seq=2 ttl=254 time=5.507 ms
Request 3 timed out
9224 bytes from 172.16.0.1: icmp_seq=4 ttl=254 time=5.529 ms
Request 5 timed out
9224 bytes from 172.16.0.1: icmp_seq=6 ttl=254 time=10.09 ms
Request 7 timed out
9224 bytes from 172.16.0.1: icmp_seq=8 ttl=254 time=5.597 ms
Request 9 timed out
9224 bytes from 172.16.0.1: icmp_seq=10 ttl=254 time=5.497 ms
Request 11 timed out
9224 bytes from 172.16.0.1: icmp_seq=12 ttl=254 time=5.491 ms
Request 13 timed out
9224 bytes from 172.16.0.1: icmp_seq=14 ttl=254 time=5.555 ms
Request 15 timed out
9224 bytes from 172.16.0.1: icmp_seq=16 ttl=254 time=6.021 ms
Request 17 timed out
9224 bytes from 172.16.0.1: icmp_seq=18 ttl=254 time=5.51 ms
--- 172.16.0.1 ping statistics ---
20 packets transmitted, 10 packets received, 50.00% packet loss
round-trip min/avg/max = 5.491/6.089/10.09 ms
If a Jumbo packet has to traverse a Nexus 5020 and a Nexus 7010, you need to configure the Policy-map in Nexus 5020 and set the system jumbomtu size in the Nexus 7010 Series Switch.
Complete these steps in order to configure the Policy-map in Nexus 5020:
!--- You can enable the Jumbo MTU for the whole switch by setting the MTU to its maximum size (9216 bytes) !--- in the policy map for the default Ethernet system class (class-default).
switch(config)#policy-map type network-qos jumbo
switch(config-pmap-nq)#class type network-qos class-default
switch(config-sys-qos)#service-policy type network-qos jumbo
Complete these steps in order to set the jumbo frame in a Nexus 7010 Switch:
!--- Set the MTU to its maximum size (9216 bytes) in order to enable the Jumbo MTU for the whole switch.
switch(config)#system jumbomtu 9216!--- Set the MTU specification for an interface.
switch(config)#interface ethernet x/x !--- By default, Cisco NX-OS configures Layer 3 parameters. In order to configure Layer 2 parameters, use this command.
In order to verify, you can ping with a packet size of more than 1500 bytes: Ping -l 9000 x.x.x.x .