The Berkeley / Fore / Marconi ESX-2400 Series
Here you are at the entrance of huge enterprise switches.

this is a single chassis of a 2400 module

Within the ESX 2400 series each single chassis (module) can work stand alone as one single unit. With a 4 unit cage (called chassis or frame too), you can plug together up to 4 units as one switch with up to 4 x 48 = 192 ports. The backplane can handle 10 Giagbit/s speed, that seems to be enough for real true wirespeed, if you run a fully load on all ports.

Each of the four modules has its own power supply, so it is slightly redundant against failure of one unit. The backplane bus is nearly passive, so if one unit fails, the others will work.

German:
Backbone Switches in Gigabit-Ethernet-basierenden Campusnetzwerken mit performanten Verbindungen von Gigabit-Ethernet und ATM-Backbones. Die L2/4-Versionen (kein Routing) der ESX-Systeme als Etagen-Switches schalten mit Wirespeed. Firewalling mit Checkpoint FW-1 Support,  Wirespeed Routing (IP/IPX/Multicast) im Ethernet und im ATM Bereich.

owever, if you try to open the chassis of the single module as an experienced network hardware specialist, you shurely become a little bit angry as to open a MAX 4000 from Ascend. It seems to be designed as a work around solution some kind of crazy. And ours are certainly young, built after Feb. 99.
After opening some units you are familiar with this kind of case and you know, where to use some more power.