kurt@hi.UUCP (Kurt Zeilenga) (09/13/87)
We have: 1) two IP ethernets separated by 120 miles 2) a T1 line between the two. I would like an IP (or ethernet if IP wasn't readly available) repeater or bridge or gateway so the two networks can talk. Anybody have any information about off the shelf products that could be used. Cost estimates would be greatly appreciated.
ron@TOPAZ.RUTGERS.EDU (Ron Natalie) (09/14/87)
There are a couple of ways to go. Since you are already IP oriented, I'd suggest IP bridges. We use ones from CISCO systems to bridge several T1 lines to Ethernets here. Proteon makes a similar box. Expect them to cost you $7000-10,000 an end. Ungermann/Bass makes a IP bridge (which can also be an Ethernet bridge (same hardware)) which is probably a little cheaper but their IP isn't quite as mature as the others. We currently run the UB box in ethernet bridge mode (I don't know how much it cost, I didn't buy it). -Ron
karn@FALINE.BELLCORE.COM (Phil R. Karn) (09/14/87)
Another way to go is to interconnect at the link (Ethernet) layer using Vitalink Translan III bridges. They support line speeds up to T1. We've been running a half dozen of them within Bellcore for a year now and they have been working very nicely. We have five large locations and about 1000 hosts in our host table. During a typical daytime minute, several hundred hosts may be active. At the moment most of our links are 250 kbps; one is already T1. All links will soon be upgraded to T1 when our DS-3 fibers are installed. The big advantage of bridging is that you can run any protocol you want across them; it doesn't have to be IP. Another is that you can freely move hosts between cable segments without having to change addresses; in a large network like ours, the administrative savings are substantial. The main disadvantage is that broadcasts go everywhere, although with T1's bandwidth this isn't much of a problem. Phil
ron@TOPAZ.RUTGERS.EDU (Ron Natalie) (09/15/87)
Although, if you have any VMS machines, I would seriously avoid protocol independant bridges of this nature. The older version of Wollongong TCP choke the vax in response to certain rather common broadcast messages. -Ron
hedrick@TOPAZ.RUTGERS.EDU.UUCP (09/17/87)
We have three situations similar to what you describe, i.e. pairs of IP networks connected by T1. We are using the following three approaches: - VAXes running Ultrix with the T1 line connected to DMR11's. Avanti T1 Mux's are used to cut down the speed, since no known DEC line controller can deal with speeds this high. This is probably the cheapest of the 3 methods, if you already have the VAXes, but also give the worst performance and has other disadvantages. - Cisco IP routers, using either Digilink T1-izers (boxes that take a vanilla 1.5Mb synchronous signal and format it for T1) or Avanti T1 muxes (for cases where we need to use the line for things other than the IP link, e.g. talking to 3270 cluster controllers at the other site). This is my preferred solution. (Of course vendors other than Cisco also make routers that would do this. You might want to talk to Proteon and U-B also.) - U-B bridges. These would also need either a T1-izer or T1 mux. These are level 2 bridges rather than level 3 routers, which have both advantages and disadvantages. (They have been discussed so often that I am not about to repeat the discussion.) The U-B bridges have worked very well, but note that you must dedicate an IBM PC or clone to boot them. (I believe the same PC can be shared for booting all U-B products.) I strongly oppose the use of this approach if the two IP networks are under different administration, and if you don't have support staff available at both ends. Junk coming from the other end can sink your network.