[j-nsp] juniper-nsp Digest, Vol 218, Issue 2

[Doug McIntyre]

On Sun, Feb 21, 2021 at 02:51:51PM +0000, David Adams JR wrote:
> Is this a place to ask or get help on a Juniper router issue?
> 
> I am trying to learn and then pass Juniper certification(s) and bout a J2320 router with a serial card.  Even though it appears serial connections are no longer used and people have said I am wasting my time trying to make a serial connection between the Juniper serial card and another Juniper J2320 serial card (I really want to make it to a Cisco 1821 router serial card), I have been trying to to find out how to successfully do so.


Sure, everybody has to start learning somewhere. We all started at the basics.

First off, what PIMs do you have inside your J2320 router?
Not sure what a Cisco 1821 is, do you mean 1812? Or an 1841? Or a 1921?
What WIC cards do you have for your Cisco router?

Second, there are two types of serial connections. Synchronous and
Asynchronous. Typically, for WAN communication, it is all synchronous
communication, which is _not_ what you'll find on your PC back when PCs
had serial ports. (those were all asynchronous). While it is possible
to setup PPP over async serial, it is rather a pain to get get it all
working, and interoping with things. These routers were not generally
designed to do that.

Typically these classes of routers were setup to do T1 PTP or
Frame-Relay network communication.

I'm not sure if it would be really worthwhile to setup a router with
sync serial communication any longer, I'd probably recommend just
doing it all with ethernet ports for a home learning lab, which is
most likely what you'll find that the work field is doing now, unless
you are going in supporting some older legacy telco support position.

But, if you are looking to do sync serial ports, I'd make sure you had
something like a dual port T1 PIM card in your Juniper router, and a
WIC-1DSU-T1-V2 card in your 1841 (assuming that is it), and connect
them up back to back with a cross-over T1 cable
https://www.freeccnaworkbook.com/blog/ccna/how-to-make-a-t1-crossover

You can get things like cross-over v.35 or cross-over smart-serial
cables for the sync serial cards (ie. without the built-in T1 CSU/DSU)
in these routers, but they are getting rare (only used for test labs),
and probably pricey. Using T1 cards is probably much much more learner
friendly if you want to do sync serial connections, and more like what
was in use back then.

Finally, some of these older low-end SOHO routers were really slow
(booting, throughput, etc) Ie. the routers were talking about here
generally can do maybe 6-8Mbps of throughput. Emulation of routers in
GNS3 probably would get you a lot more bang for the buck. But yeah, I
get the desire to actually touch hardware too (not that I get
to actually see the hardware any more).