While configuring Nexus Line cards especially of M (M1) series like “N7K-M132XP-12”, an error may be seen as below –
“ERROR: Ethernet1/2: Config not allowed, as first port in the port−grp is dedicated”.The error relates to the concept of “port-group”.
The term “Port-Group” can be better understood in reference to “N7K-M132XP-12” line card which has 32 * 10G ports. In the line card, each of 4 ports are grouped together i.e. they share the 10G bandwidth amongst themselves. This means that not all 32 ports support 10G at same time and that each of 4 ports have been grouped to share 10G. Considering that each group of 4 ports shares 10G, this makes total bandwidth supported by Line card equal to 10 * (32/4) = 80 Gbps and not 320 Gbps.
Now that we understand that each set of 4 ports form Port Group in “N7K-M132XP-12” line card, lets further detail into how the port members are arranged in Port-Groups. Below diagram shows how port groups are formed with ports using same hardware ASIC.
Below table shows the port groups in shared mode and port number in case of dedicated mode:
DEDICATED MODE CONFIGURATION –
Shared mode is the default mode. For configuring a port as dedicated, we need to first admin down the four ports in the group then change the rate mode to dedicated and at last un shut the port.Below is config to enable dedicated mode on interface Eth1/1 –SHARED MODE CONFIGURATION –
In order to specify interface group where we want to configure sharing mode, 1st shut the port in dedicated mode and then configure all the 4 ports to be part of shared mode as below – VERIFICATION –
To verify the configuration of the particular port, you can use below command: