Introduction
This document describes issues caused when you configure a Jumbo Maximum Transmission Unit (MTU) packet in a Nexus 5000 Series Switch.
Prerequisites
Requirements
There are no specific requirements for this document.
Components Used
The information in this document is based on these series of Nexus switches:
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.
Conventions
Refer to the Cisco Technical Tips Conventions for more information on document conventions.
Background Information
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.
Configure
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
Configurations
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:
| 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-pmap-c-nq)#mtu 9216
switch(config-pmap-c-nq)#exit
switch(config-pmap-nq)#exit
switch(config)#system qos
switch(config-sys-qos)#service-policy type network-qos jumbo
|
Refer to Cisco Nexus 5000 Series NX-OS Layer 2 Switching Configuration Guide, Release 4.2(1)N1(1) for more information.
Complete these steps in order to set the jumbo frame in a Nexus 7010 Switch:
| Nexus-7010 |
!--- 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.
switch(config-if)#switchport
switch(config-if)#mtu 9216
switch(config-if)#exit
|
Verify
In order to verify, you can ping with a packet size of more than 1500 bytes: Ping -l 9000 x.x.x.x .
You can also issue the show interface ethernet port/slot command in order to verify if the Jumbo frame is set.
On the Nexus 5000, enter the show queuing interface ethernet 1/1 command:
Nexus5000#show queuing interface ethernet 1/1
Ethernet1/1 queuing information:
TX Queuing
qos-group sched-type oper-bandwidth
0 WRR 50
1 WRR 50
RX Queuing
qos-group 0
q-size: 243200, HW MTU: 9280 (9216 configured)
On the Nexus 7000, enter the show interface ethernet 1/9 command:
Nexus-7010#show interface ethernet 1/9
Ethernet1/9 is up
Hardware: 10000 Ethernet, address: 0000.0000.0000 (bia 0000.0000.0000)
MTU 9216 bytes, BW 10000000 Kbit, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA
Port mode is access
full-duplex, 10 Gb/s, media type is 10g
Beacon is turned off
Auto-Negotiation is turned off
Input flow-control is off, output flow-control is off
Rate mode is dedicated
Switchport monitor is off
Last link flapped 00:57:24
Last clearing of "show interface" counters 00:56:14
30 seconds input rate 0 bits/sec, 0 packets/sec
30 seconds output rate 360 bits/sec, 0 packets/sec
Load-Interval #2: 5 minute (300 seconds)
input rate 0 bps, 0 pps; output rate 448 bps, 0 pps
RX
5894254 unicast packets 0 multicast packets 0 broadcast packets
5894254 input packets 29108950332 bytes
0 jumbo packets 0 storm suppression packets
0 runts 0 giants 0 CRC 0 no buffer
0 input error 0 short frame 0 overrun 0 underrun 0 ignored
0 watchdog 0 bad etype drop 0 bad proto drop 0 if down drop
0 input with dribble 0 input discard
0 Rx pause
TX
5894228 unicast packets 2225 multicast packets 0 broadcast packets
5896453 output packets 29109001641 bytes
0 jumbo packets
0 output error 0 collision 0 deferred 0 late collision
0 lost carrier 0 no carrier 0 babble
0 Tx pause
0 interface resets
Note: The Jumbo counter on Nexus 7000 series is not supported and the Tx and Rx frames show null value, but if you note the MTU size it displays the configured Jumbo frame.
Troubleshoot
There is currently no information available to troubleshoot this configuration.
Related Information
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