router problem

Rats · Guest

Hi
I am facing a problem with my 1720 router

My remote router pings till i open a web site. the moment i open a web
site on my far it stops pinging.

There are lot of input and CRC errors in sh int s0 output.

i connected both the router with help of CSU/DSU (Modems) one in master

mode and one in slave mode but problem still continued. Media was
totally by passed. Any one can tell me where is the fault in the router

or modems. Router is WIC 2 AS smart serial. Modem type is Multitech AM
100 and company owned.

Please advise on priority.

rdymek@gmail.com · Guest

Can you please elaborate on the design of this? Are you running DDR
(Dial Demand Routing aka dial on demand), or does the Multitech do the
DDR for you?

Do you have NAT/PAT enabled?

Simply describing the network design a bit more detailed would really
help, as of right now there is not enough information to make any sort
of judgement as to whats going on.

Ryan

clubfoot · Guest

"Rats"

You may also consider the T1 comming in from the phone co. I have seen some
strange things with T1's. At the remote site can you find the NIU? If so are
all the lights green or are any amber or red? Most NIU's at least will have
LED's that say "L1" and "L2" and depending on the make and model will have
other LED's. When I used to help maintain a large MAN one of the first
places I looked was the NIU's. This will tell you if at least the
point-to-point physical link is OK. The L1 and L2 should NEVER be anything
but green - they show the status of the LOOP's between your demarcation
point and the phone co. A yellow, red or no light means the problem is
something outside of your office and is the responsibility of the phone
company to fix. If it has an LED labeled DS1 and that is not green then the
problem is inside your building - probably bad wiring or a bad or wrongly
configured CSU/DSU. Our plan of attack was always to start with layer 1 and
work your way up - it seemed to be the quickest way to find and fix issues
we had with new installs or existing ones. The phone co. always tried to
scare us with the threat of an expensive charge if the problem was not there
fault but using things like knowledge of T1's and "head-to-head" tests with
T1 testers like with 2 TBERD's we were able to prove to them the problem was
with them. You might also check the SH INT S0 to see if you have any errors
like CRC errors or any of the others. From the remote site, clear all
counters, check them after a few minutes and see if they increase, then hit
a web site. Note the error counters that jump up drastically. This will help
to point you to where to look. Most often CRC errors are due to, but not
allways, something on the telco side of things or internal wiring. CRC are
often layer 1 errors. Here in Arizona we most often see CRC and framing
errors, usually during the summer when the temp. can reach 110 to 115 and
the heat would fry the "doublers" that the telco. would use to extend the
T1's. No more then 2 doublers max. If you can connect to and log into the
NIU then it will give you a nice overview of the T1 circuit including how
many doublers are in your loop, the db of each leg of the circuit (should be
less then 3 db diff. between each parallel leg of the loop and in the low
20's), clock rate (should be no more then -/+10 of 1.544). Also, some
doublers will show an X on the leg that has a problem. If your not getting
your T1 form the local telco. then you may have larger issues since all
third parties have to lease the physical T1 from the local telco and now you
have to point fingers to, and prove which one (owner of the physical cable -
local telco. or leaser AT&T or others is responsible). Saving a few dollars
up front does sometimes have HIGH costs. Note, it is not legal to log into
the NIU, that would be trespassing in telco. space and you could get a fine
for doing so - I'm not advocating that. Butt, if you do know the info. that
the NIU shows then that would help to prove that the problem is in the
telco. side of the circuit. I guess I just know this from looking over the
sholder of the many telco. techs that I have called to look at our circuits
over the years.
Anyway, the problem could be in configuration of the router and I may be way
off. Does the router work fine in a lab connected with a T1 x-over cable
(1,2 - 4,5 swaped)? If so then they should work fine in the field!
Just a thought. Let us know if you get it all worked out and what the fix
was.

Chris
<rdymek@gmail.com> wrote in message
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