Cabletron Systems MMAC-5FNB Networking Manual

Also see for MMAC-5FNB: Overview and setup guide

Contents

Cabletron Systems MMAC-5FNB Networking Manual Manual pdf 110 page image

Ethernet5-30Segmentation - Special CasesSegmentation - Special CasesPort AssignmentIn most Ethernets requiring modification, congestion is the problem. Ethernet hasa tendency to get sluggish around 40% bandwidth utilization. When you move upto sustained rates of 50 or 60% utilization, the situation becomes aggravating.Above 60% sustained bandwidth utilization, the Ethernet network may be acollision hotbed, while user processes have slowed to the point of hibernation.One way that we could solve this is through the segmentation and bridgingmethods we have already discussed. Segmentation of the network works verywell in several situations, but there are some instances where the assignment ofusers to a backplane segment through an entire module simply does not makesense. In several cases, it would be much more efficient to place a handful ofpeople on one network, a few people on a separate network, and the vast majorityof stations on a third. In the Multichannel configuration this is entirely possible. Itinvolves the very confusing and aggravating process of deciphering the wiringlabeling scheme, moving jumper cables from one port and module to another, andreconfiguring users based on the “switchboard operator” system of plugging theright cable into the right module. When you run out of ports on a module, youmove to the next module that is on that channel. When you run out of ports in theentire channel, however, you need to go back to the drawing board.A particularly effective and efficient solution to the segmentation system issue inEthernet is the technology of Port Assignment, often called switching, portswitching, or Virtual LAN configuration. You may run into any of these terms inthe industry, and even within Cabletron Systems documents. The basis ofmisunderstanding comes from the ubiquity of the term “switching” innetworking. “Switching,” by itself, may refer to Asynchronous Transfer ModeSwitch Configuration and Operation, Ethernet Switching, Token Ring Switching,FDDI Switching, Port Assignment, Channel Switching, or Bank Switching. Someof these terms refer to similar things, others do not. This is why the term“switching” needs to be clarified. Make sure you know what type of switching isbeing referred to in any networking discussion.Port Assignment allows a Network Manager to configure individual ports on theMedia Interface Module to connect to a particular backplane Ethernet channel. Inthis way, a port assignment module could have two users on Channel A, six userson Channel B, and 14 users on Channel C. If someone needed to be moved tochannel A for a week while working on a project involving a lot of file transferwork with the stations on Channel A, a Network Manager could simply notify theMedia Interface Module to connect the ports they are utilizing to Channel A. It isthat simple. No swapping of jumper cables or re-configuration of modules.