Mounting Requirements for Installing Multiple Hubs
Position the hub you want to be numbered 1 at the top of the stack. When an NMM is installed in the stack, it assigns unit numbers starting from the top of the stack. For information about the unit numbering convention, see “Unit Numbering Convention” in Chapter 3.
For rack installations, you should leave enough room in the rack to expand the stack to six hubs. Each hub occupies 1.5 EIA rack-mount spaces. For table or shelf installations, make sure the shelf or table can support the weight of six fully equipped hubs. See “Site Preparation,” earlier in this chapter, for a list of table and shelf installation requirements.
Installing Optional Modules in the Hub
You can install an optional 100BASE-T media adapter in the media adapter slot and an optional 100BASE-T host module or 100BASE-T NMM in the expansion slot. You should install the modules in the hub before connecting power to the hub. If the modules are installed in these slots when the hub is powered, the hub may reset when the module is inserted into the slot. During a reset, you will temporarily lose port connectivity in the hub that is reset. In nonredundant management configurations, if you reset a hub equipped with an NMM, you will temporarily lose management to the entire stack of hubs.
Installing Network Management Modules
Any Express hub in a stack can accommodate the 100BASE-T NMM, however, it is recommended that you install the NMM in the hub at the top of your stack. When an NMM is installed in the stack, it automatically assigns and stores the numbers of the hubs in the stack.
In a redundant management configuration, you can install two 100BASE-T NMMs in two separate hubs in the stack. One of the NMMs is designated the master NMM and actively manages the stack, while the second NMM operates in a standby mode. For more information about the NMM and redundant management configuration, refer to the documentation that shipped with your NMM.