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Cisco's web page had documentation on routing technology, but
unfortunately it didn't mention anything similar to the 'choking' portion of our problem.
The section on bridges/switches did provide more information that I think is relevant to
our problem. When dealing with remote bridging, the bridges have to compensate for the
different between LAN and WAN speeds (LAN speeds tends to be much much higher than WAN
speeds). Here is an exert from Cisco's documentation. "Remote bridging presents several unique internetworking challenges. One of these is the difference between LAN and wide area network (WAN) speeds. Although several fast WAN technologies are now establishing a presence in geographically dispersed internetworks, LAN speeds are often an order of magnitude faster than WAN speeds. Vastly different LAN and WAN speeds sometimes prevent users from running delay-sensitive LAN applications over the WAN. Remote bridges cannot improve WAN speeds, but can compensate for speed discrepancies through sufficient buffering capability. If a LAN device capable of a 3-Mbps transmission rate wishes to communicate with a device on a remote LAN, the local bridge must regulate the 3-Mbps data stream so that it does not overwhelm the 64-kbps serial link. This is done by storing the incoming data in on-board buffers and sending it over the serial link at a rate the serial link can accommodate. This can be achieved only for short bursts of data that do not overwhelm the bridge's buffering capability." Cisco goes on to talk more about their High-Speed Serial Interface (HSSI) which solves many of the problems involving high-speed communication over WAN links. Unfortunately, this is for handling traffic from high-speed LANsto very high-speed WANs (T3 or above) and doesn't appear to me to be very usefull when dealing with the standard T1 link to the outside world. While 3com had extensive documentation as to the technology solutions they offer, I had trouble finding information that really pertained to what we are trying to do. The main focus nowadays seems to be on using Gigabit Ethernet or an ATM backbone coupled with a very high-speed link to the outside world. I didn't read all the documents, but browsed over the ones that I thought looked relevent so there could be some information from 3com on our subject that I missed. The Lucent Technologies page is moving at a snails pace in loading at the moment (and this is in lynx), so I will have to look into any sort of technical documents they have later. Although my search for information on how other companies hardware handles the 'choking' problem hasn't been all that sucessfull, Cisco does give us a jumping place on how to implement choking. I'll look more this weekend at the 3com/Lucent information, and hopefully some other manufacturers of routing/switching/bridging hardware. |
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Copyright © 1999 by Jim Garlick. All rights reserved. |
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