sponsible for port forwarding of a number of ports. On the 32-port 10 Gbps blade on the Nexus 7000, each ASIC controls four ports. What this means to you is that you can only get 10 Gbps of throughput for every four ports Nexus Design Features on the blade (4:1 oversubscription). This may sound like a terrible thing, but it's ac- tually very common on modules of this type. I've seen interesting issues attributed to ASIC failures. Once, on a 6509, we had very strange problems with what seemed to be a random group of servers. The admin discovered that if he moved the server to a dif- ferent port on the switch, the problem went away. When I started to dig into the physical connections, I discovered that the servers experiencing the problem were all connected within a contiguous range of six ports. These ports were all controlled by a single ASIC, which had gone bad. We migrated the servers off the offending ports, then made arrange- ments to get the blade replaced. The Nexus 7000 allows you to dedicate all the ASIC's resources to one port on these modules in what is called dedicated rate-mode. When you do this, it disables all of the other ports controlled by that ASIC. The groups of ports are not contiguous; in other words, a single ASIC controls ports el/1, 3, 5, and 7, while a different ASIC controls ports e1/2, 4, 6, and 8. This may seem odd until you look at the front of the blade. As you can see from Figure 18-13, the pattern corresponds to the physical layout of the ports on the blade. Ports 1, 3, 5, and 7 are all physically contiguous and share the same hardware connections (and therefore ASIC) within the module. This module even marks the ports that you can configure as dedicated ports. N7K-M 132XP-12L STATUS Figure 18-13. A 32-port 10 Gbps Nexus module with marked dedicated ports; courtesy of Cisco Systems, Inc.; unauthorized use not permitted So why would we want to do this? Most devices rarely utilize the full capacity of an interface, which is why the ports share an ASIC. Certain devices do require a hi