Date: Wed, 8 Aug 2001 22:38:48 -0700 From: "Ted Mittelstaedt" <tedm@toybox.placo.com> To: "Chris Fedde" <chris@fedde.littleton.co.us> Cc: "Odhiambo Washington" <wash@wananchi.com>, "FBSD-Q" <freebsd-questions@FreeBSD.ORG>, <kweheria@iconnect.co.ke> Subject: RE: Isn't it true? Message-ID: <000101c12095$90615b80$1401a8c0@tedm.placo.com> In-Reply-To: <200108080700.f7870l440614@fedde.littleton.co.us>
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>-----Original Message----- >From: cfedde@fedde.littleton.co.us >[mailto:cfedde@fedde.littleton.co.us]On Behalf Of Chris Fedde >Sent: Wednesday, August 08, 2001 12:01 AM >To: Ted Mittelstaedt >Cc: Odhiambo Washington; FBSD-Q; kweheria@iconnect.co.ke >Subject: Re: Isn't it true? > > >On Tue, 7 Aug 2001 22:28:46 -0700 "Ted Mittelstaedt" wrote: > +------------------ > | Hi Odhiambo, > | > | Sorry about the top post here, but I wanted to give you the detailed > | explanation before you start spending money on things, and before > | the rest of the eager beavers here had got you totally confused. :-) > +------------------ > >Ted, > >It appears that you have confused the OP's product selection with >some other device. I looked over the description of the Mainstreet >2701 at > > http://www.cid.alcatel.com/doctypes/product/html/ > >The 2701 appears to be an async NTU for use in a private TDM network. I looked up the PDF file again at that URL and I agree with you that the 2701 is capabable of doing both sync and async - according to the PDF. That is something that I overlooked and should have mentioned. However, the PC serial port cannot do 64K async because the clock chip used in a PC will not divide into that frequency. 56k is as close as you get. He did say that they were using a Cisco 25xx at the other end. Frankly if it's plugged into the AUX async port of the 25xx then that router is way overkill and as you point out he should be using PC's. Also the 25xx AUX async port is just like the PC port in that it cannot do 64K either. Since he listed 64K on the circuit diagram I used that to assume that it's in the sync port of the 25xx. If it is plugged into the sync port of the Cisco using the usual sync V.24 cable then he can't use a PC with an async port at the other end. It is probably quite possible to run a pair of 2701's at 56k async mode on a private TDM. However he is going to have to find out from the Telco if the line that they are supplying is a private point-to-point and if he can do anything other than 64k synchronous on it. Certainly if the Telco tells him that both ends of the line must use line clock provided by the Telco then he can't do it. If he can do it and he wants to keep the Cisco 25xx at the other end then he will need to plug the other 2701 into the AUX port of the Cisco, NOT the sync serial port. Also, of course doing it this way will reduce the throughput to a little below 56K because you lose some with the clocking. >From what I've read it looks like the OP is right on track to a >robust solution assuming that the circit between the two 2701 is >two unloaded copper pair The problem that I have with this is that he said in his first mail that the separation distance was 10km. The PDF for the 2701 claims the _maximum_ line distance that can be supported is 7.2km Based on that I assumed that he is specing them because the Telco told him to use them - because the line is not a true unloaded copper pair, but instead is terminated at the CO and multiplexed with other circuits. That would almost certainly demand 64k synchronous and likely both sides would have to use line clocking. Some countries which have nationalized telephone systems will dictate the requirements for the customer connection equipment, and I could well imagine that the Mainstreet might be on the list of approved customer prem equipment. >A standard PC style 16550A UART should >work perfectly. there is no need for a fancy synchronous interface >card. Infact one will not work with the V.24 interface on the 2701. > That is NOT true. The PDF file lists all units as capabable of doing both sync and async except for the 2801 which can do only sync. >For this application the 2701 is a bit of overkill, If it is surplus >hardware that's great. I also am somewhat mystified by the selection of the Mainstreet 2701. For starters, it appears that Mainstreet doesen't exist as a company any more and the product is ancient technology. In fact, the description of the Mainstreet explicitly says it was designed to use with Mainstreet 3600 family of multiplexors. I would assume from that wording that if the things don't work here that Alcatel will use that to not support them being plugged into Cisco's. :-) >But if he is buying hardware to do this >and has line of sight I might recomend a pair of ORiNOCO 802.11b >cards and a pair of dish antennae. > Can he even do that where he is? Some countries freak at the thought of their citizens running transmitters of any kind and ban them outright. Also 10km is close to the edge of reachability for the 2.4Ghz 802.11 stuff. This discussion is actually raising more and more questions. Odhiambo, care to comment? Ted Mittelstaedt tedm@toybox.placo.com Author of: The FreeBSD Corporate Networker's Guide Book website: http://www.freebsd-corp-net-guide.com >chris > > +------------------ > | > | You see, here in the US we don't use icky things like 64k sync circuits > | anymore and most WAN techs are very unfamiliar with the oddball hardware > | used to connect that stuff. Instead, high speed WANS here are >based around >a > | thing called a T1 or 1/24th of a t1 called a 56k circuit. We use things > | called DSU's that plug them in, which are different than the DTU's like > | the Mainstreet 2701. > | > | By the way, thanks for the plug. :-) > | > | For starters, for just a single point-to-point link you don't need > | Zebra. At most if one side has a gateway to the Internet you might have a > | couple of static routes in the routers. Zebra, gated, and routed >are intend >ed > | to be used for WANS that have redundant links because as links >come up and g >o > | down the routes change, and the routing daemons manage those route table > | changes. Your WAN bandwidth is precious and expensive and you >don't want to > | waste it by shipping routing updates across it for routes that will never > | change. > | > | Secondly, yes you can use a FreeBSD box in place of a Cisco >router. I do >it > | at the ISP that I admin and I run BGP4 with a full BGP feed on >it. I have 2 > | T1's and 2 100BaseT Ethernet connections into the box, and 3 of the > | connections are Internet feeds. It works fairly well. The route table on > | that system is close to 100k routes. I use gated. > | > | Now, in your case I looked up the specs for the Mainstreet 2701. First > | of all the serial cable that comes out of it is a V.24 interface, it is > | NOT an X.21 interface!! Your not going to be happy with the results > | attempting to plug it into an X.21 interface card. ;-) > | > | Secondly, it appears to be a _synchronous_ RS232C interface. While it > | is electrically compatible with a PC serial port, a garden variety PC > | serial port is asynchronous, NOT synchronous, so that won't work either. > | > | As far as I know, there's only 2 vendors that currently are selling > | sync serial cards with V.24 that will run under FreeBSD, the >first is Sangom >a, > | and the second (the vendor that I use) is a WANic 400 or 405, from SBS > | Technologies. > | > | In my case I actually use the RISCom cards, they are the >predicessor cards > | to the WANic 400/405. It's the same chipset, and made by the >same vendor, t >he > | only difference is that one card is ISA the other is PCI. > | > | In fact, the sync controller chipset in both of those cards is the > | HD64570 chip, which is EXACTLY the same chip as Cisco uses in the 25xx > | series of routers. (2501, 2511, 2522, etc.) > | > | Now for the bad news: a new WANic is going to cost about $800 >USD unless > | you can possibly find one used. (and goodness knows I've tried - the 2 > | RISCom cards I got were used and they were eye-raising expensive >as it was) > | This is more money than if you get up on Ebay and buy yourself a >used Cisco > | 2522 or 2501 or something like that, plus cabling. (In fact, >I've got a use >d > | 2501 with a RS232 sync cable that I'd sell but if you want to >pursue that ta >ke > | it offline with me. I'm sure that you can find used vendors that >are in you >r > | country without the messiness of the import/export stuff) > | > | So, in summary if you want to use FreeBSD to save money, you >won't because > | the cost of a sync V.24 is going to be the killer. If, however, >you want to > | do it just for fun, then that's fine - but remember that you have got 2 > | offices there and if your toy goes offline in the middle of the >day your goi >ng > | to have a lot of pissed-off people. :-) > | > | In our case the cost of a Cisco 7206 (the minimum Cisco capabable of > | running BGP without up and dying) is about $30,000 USD so that >was plenty of > | financial incentive to go the BSD route. (no pun intended) > | > | Ted Mittelstaedt >tedm@toybox.placo.com > | Author of: The FreeBSD Corporate >Networker's Guide > | Book website: >http://www.freebsd-corp-net-guide.com > | > | > | >-----Original Message----- > | >From: owner-freebsd-questions@FreeBSD.ORG > | >[mailto:owner-freebsd-questions@FreeBSD.ORG]On Behalf Of Odhiambo > | >Washington > | >Sent: Tuesday, August 07, 2001 8:11 AM > | >To: FBSD-Q > | >Cc: kweheria@iconnect.co.ke > | >Subject: Isn't it true? > | > > | > > | >Such a dumb subject line but isn't it true that nobody in the > | >knowledge-rich FreeBSD world has ever gone out of their 'mind' (I mean > | >their way) and done something like substituting a FreeBSD box for a Cisco > | >router like this: > | > Telco Link _____ > | > LAN<-->[____]----->[...]================[...]----->|_____|<----->LAN > | > FreeBSD Mainstreet Mainstreet Cisco > | > Box 2701 2701 2522 > | > > | > > | >If someone _ever_ tried it, I request to share in their feat ;-) > | > > | > > | >Thanks > | > > | > > | >-Wash > | > > | >-- > | >Odhiambo Washington > | >Wananchi Online Ltd., > | >wash@wananchi.com 1st Flr Loita Hse. > | >Tel: 254 2 313985 Loita Street., > | >Fax: 254 2 313922 PO Box 10286,00100-NAIROBI,KE. > | > > | >To sentence a man of true genius, to the drudgery of a school is to put a > | >racehorse on a treadmill. > | >-Charles Caleb Colton > | > > | >To Unsubscribe: send mail to majordomo@FreeBSD.org > | >with "unsubscribe freebsd-questions" in the body of the message > | > > | > | > | To Unsubscribe: send mail to majordomo@FreeBSD.org > | with "unsubscribe freebsd-questions" in the body of the message > +------------------ > >-- > Chris Fedde > 303 773 9134 > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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