Shared vs Dedicated Mode of Ports in Nexus 7000 "ERROR: Ethernet1/4: Config not allowed, as first port in the port−grp is dedicated" To understand this, we need to understand what is port-group. Below is the image of N7K-M132XP-12 Line card. This line card has 32 ports and all are 10 Gig port. So what does that mean? Does it mean thate ach one of them is a 10 Gig port and we can have all of these 32 ports connected at the same time and we should be able to get 320 Gbps speed. Yes, they are 10 Gig ports; HOWEVER, that 10 Gig is shared among 4 ports in a group. That group is basically all the ports on same hardware ASIC.
As per the below pic, you can see that even or odd continuous ports are on one side and each group of four ports are on same hardware ASIC. This is a port-group and first port of the group is marked YELLOW as you can see in below diagram.
So, being said that N7K-M132XP-12 has 32 10G ports, it means that each port-group (group of 4 ports for this line card) share 10G speed among themselves. YES!! that is correct. All ports dont get 10G dedicated bandwidth. So, the total capacity of the card is 80G, not 320 (as we were expecting) as there can be 8 port-grp of 4 ports each. This is designed on the concept that "Chances are less that all devices are sending data at the same time". So, 1,3,5,7 will be in same port-grp and similarly 2,4,6,8 and so on...!! So, 4 ports in a group will share the total available bandwidth of 10G.