In this FREE six-day email course, you'll learn from Janis Griffin, Database Performance Evangelist. She'll teach 12 steps that you can use to optimize your queries as much as possible and see measurable results in your work. Get started today!
Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.
Have a better answer? Share it in a comment.
From novice to tech pro — start learning today.
Cut-through in *no way* intentionally jabbers a port. BTW, the definition of jabber is wrong too - a jabber is defined in the 802.3 standard as a frame longer than the maximum legal size (1518 bytes). It's not necessarily garbage.
Garbage certainly can result in the case of bad frames, since the switch forwards the frame before the it realizes the frame has an error. (note that switches (layer 2, not layer 3) do *frames*, not *packets*. In my experience, sources of bad frames *tend* to be fairly localized (bad NIC, misbehaving driver or software on a PC), and many switches that use cut-through also temporarily change from cut-through to store-and-forward if the error level on a port goes too high. There are also several different kinds of cut-through: adaptive, FastForward, and FragmentFree (FragmentFree is the default switching mode on the Catalyst 1900 series switch).
A major issue with cut-through is that it doesn't work when going from 10Mbps to 100Mbps - e.g. a 24-port 10mbps switch with a 100 mbps uplink. For this and other reasons, cut-through is much more common on the edge rather than anywhere near the core.
All that said, switching is ALWAYS better than a shared medium. The reason you sometimes see a mixed network is purely cost. The reason you see people still selling hubs is the same - hubs are cheaper, since there is less processing and no memory involved.
if you are planning a relatively simple network (say, less than 100 users, and few segments), with fairly reliable hardware and software, cut-through can be used as long as it's cost effective. Once you start getting larger, straight store-and-forward is much better, once you factor in troubleshooting issues. Even if you get better deals with cut-through, I'd stay away from them since it's very hard to troubleshoot the bad frames that sneak through. Also, if you need to reconfigure your network later and use the swtich to go from 10Mbps to 100Mbps, you won't have to figure out which ones are cut-through if you don't buy any in the first place.
Once final note: I feel that switches make management and troubleshooting MUCH more straightforward than a shared network. They also tend to contain problems much better. Yes, they make sniffing a bit more difficult. But they also make people stealing information much more difficult (network managers are not the only ones sniffing! :)) If I need to sniff an entire network, I just configure a port as a mirror of the uplink, and then I can sniff to my heart's content. I'd much rather do that than compromise either efficiency or security of my network.
Did the original question sound like homework to anyone else?