In a nutshell, host optimized ports are over provisioned internally, while target optimized ports have full internal bandwidth.
Host optimized ports normally exist in 8 port groups, where those 8 ports share a lower bandwidth "hidden" port internally. Think of it like chaining switches internally.
Now, you can configured host optimized ports for targets, or ISL's, you just have to be careful not to over provision that hidden port that services the port group.
Here is a snipped from MDS documentation that describes how to do that
Configuring 32-port Switching Modules and Host-Optimized Ports
The 32-port 1/2-Gbps switching module contains 8 port groups of 4 ports each. When configuring these modules or the host-optimized ports in the Cisco 9100 Series, the following guidelines apply:
•Any (or all) full line rate port(s) in the Cisco MDS 9100 Series can be included in a PortChannel.
•The host-optimized ports in the Cisco MDS 9100 Series are subject to same PortChannel rules as 32-port switching modules--only the first port of each group of 4 ports is included in a PortChannel.
-You can configure only the first port in each 4- port group (for example, the first port in ports 1-4, the fifth port in ports 5-8 and so on) as an E port. If the first port in the group is configured as a PortChannel, the other three ports in each group (ports 2-4, 6-8 and so on) are not usable and remain in the shutdown state.
-If any of the other three ports are configured in a no shutdown state, you cannot configure the first port as a PortChannel. The other three ports continue to remain in a no shutdown state.
In the Cisco MDS 9100 Series, the left most groups of ports outlined in white (4 ports in the 9120 switch and 8 ports in the 9140 switch) are full line rate like the 16-port switching module. The other ports (16 ports in the 9120 switch and 32 ports in the 9140 switch) are host-optimized like the 32-port switching module. Each group of 4 host-optimized ports have the same rules as for the 32-port switching module.
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--Colin
www.colinmcnamara.com
