chen@cunixc.UUCP (11/05/87)
We at Columbia University are planning for a Wide Area Network. This net will connect three CU campuses which are 12 to 15 miles apart in a triangular topology. A fourth campus might eventually come into the picture also. Our plan is to extend our Ethernet using gateways via common carrier T1 service to these campuses. Since we also want to have sync and async traffic on the T1 link besides the Ethernet traffic, we want to put a T1 mux between the gateway and the CSU. We already have a 56Kbps Ethernet link through Datatel T1 muxes using Vitalink's TransLan bridges. But the Datatel muxes can only handle a single T1 interface and the Vitalink boxes are level 2. My question is whether anyone has had experience with using part of the bandwidth of T1 muxes for Ethernet extensions of this sort. In particular, what kinds of clocking concerns are there from both the point of view of the gateway and the mux. Does anyone have their gateways running at speeds that are higher than 64Kbps? If so, what if there is a tail circuit from the mux to the Ether? Are there line drivers that can handle more than 64Kbps, up to a little less than 1.544Mbps? We've spoken to Timeplex about their miniLink products and they say there should be no problems with what we want to do using their equipment. But we would feel a lot better if we heard that from people that have actually done this kind of thing. In addition, any information with the kind of muxes used, the kind of problems experienced, CSU's, etc. will be greatly appreciated. The gateways that we are looking at are Cisco and Proteon. Thanks in advance for any and all information. If other people are interested in the answers I get, I will post a summary. Bill Chen Data Communications Columbia University Internet: chen@cunixc.columbia.edu
ron@topaz.rutgers.edu (Ron Natalie) (11/11/87)
Timeplex rots. Rutgers University has 4 campuses joined by T1 lines. Generally we reserve a megabit from the T1 line for the Ethernet-Etheret link. The rest is used for some IBM-releated stuff, RJE's and things. The multiplexors are Avanti Ultramux. These allow you to allocate any fraction of bandwidth to any portion of the serial lines. The Ethernets are bridged by CISCO IP/DECNET gateways. Each box has one of their T1 serial cards that can support 2 T1 (or slower links). They also make a somewhat cheaper 56K board. -Ron