Nexus 5010/5020 are Unified fabric switches which support Ethernet and Fibre Channel over Ethernet(FCoE). In Nexus 5010/5020, by default, class-default ethernet traffic goes into a separate drop class queue(qos group 0) and FCoE traffic goes into a non-drop queue(qos group 1). The default MTU for class-default traffic is 1500 bytes and default MTU for FCoE class is 2158. Default MTU can be verified with following command.
24.10.5020A.1# sh queuing interface ethernet 1/17
Ethernet1/17 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: 1600 (1500 configured)
drop-type: drop, xon: 0, xoff: 243200
Statistics:
Pkts received over the port : 0
Ucast pkts sent to the cross-bar : 0
Mcast pkts sent to the cross-bar : 0
Ucast pkts received from the cross-bar : 0
Pkts sent to the port : 3354776292
Pkts discarded on ingress : 0
Per-priority-pause status : Rx (Inactive), Tx (Inactive)
qos-group 1
q-size: 76800, HW MTU: 2240 (2158 configured)
drop-type: no-drop, xon: 20480, xoff: 38400
Statistics:
Pkts received over the port : 1985
Ucast pkts sent to the cross-bar : 1982
Mcast pkts sent to the cross-bar : 3
Ucast pkts received from the cross-bar : 0
Pkts sent to the port : 0
Pkts discarded on ingress : 0
Per-priority-pause status : Rx (Active), Tx (Inactive)
Total Multicast crossbar statistics:
Mcast pkts received from the cross-bar : 3359246715
24.10.5020A.1#
If a user needs to change MTU for class-default traffic, the following configuratiion would be needed. Note that if the Nexus 5010/5020
is configured to be in vPC pair, the change will need to be done on both the switches. If the switches are running NX-OS 4.x, QoS configuration is a vPC Type-1 inconsistency and will bring down vPCs and hence the configuration needs to be done in a maintenance window. If the switches are running any 5.x NX-OS, QoS is a Type-2 inconsistency and will not affect traffic.
24.10.5020A.1# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
24.10.5020A.1(config)# policy-map type network-qos jumbo
24.10.5020A.1(config-pmap-nq)# class type network-qos class-default
24.10.5020A.1(config-pmap-nq-c)# mtu 9216
24.10.5020A.1(config-pmap-nq-c)# exit
24.10.5020A.1(config-pmap-nq)# exit
24.10.5020A.1(config)# system qos
24.10.5020A.1(config-sys-qos)# service-policy type network-qos jumbo
24.10.5020A.1(config-sys-qos)# end
24.10.5020A.1# sh run ipqos
!Command: show running-config ipqos
!Time: Sat Jun 23 08:49:17 2012
version 5.1(3)N2(1a)
class-map type qos class-fcoe
class-map type queuing class-all-flood
match qos-group 2
class-map type queuing class-ip-multicast
match qos-group 2
class-map type network-qos class-all-flood
match qos-group 2
class-map type network-qos class-ip-multicast
match qos-group 2
policy-map type network-qos jumbo
class type network-qos class-fcoe
pause no-drop
mtu 2158
class type network-qos class-default
mtu 9216
system qos
service-policy type network-qos jumbo
Since MTU changes are done via policy-map, in Nexus 5010/5020, to verify the changes, a user cannot use "show interface" commands but
should use "show queuing" command. Here is an example.
24.10.5020A.1# show queuing interface ethernet 1/17
Ethernet1/17 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)
drop-type: drop, xon: 0, xoff: 243200
Statistics:
Pkts received over the port : 0
Ucast pkts sent to the cross-bar : 0
Mcast pkts sent to the cross-bar : 0
Ucast pkts received from the cross-bar : 0
Pkts sent to the port : 3354779288
Pkts discarded on ingress : 0
Per-priority-pause status : Rx (Inactive), Tx (Inactive)
qos-group 1
q-size: 76800, HW MTU: 2240 (2158 configured)
drop-type: no-drop, xon: 20480, xoff: 38400
Statistics:
Pkts received over the port : 1985
Ucast pkts sent to the cross-bar : 1982
Mcast pkts sent to the cross-bar : 3
Ucast pkts received from the cross-bar : 0
Pkts sent to the port : 0
Pkts discarded on ingress : 0
Per-priority-pause status : Rx (Inactive), Tx (Inactive)
Total Multicast crossbar statistics:
Mcast pkts received from the cross-bar : 3359249858
24.10.5020A.1#
