T1 Acceptable Errors

[h.parsons]

I have a point to point T1 using two 1751 routers with integrated dsu (v2) I know there is a isssue with these cards but what I wanted to know is a certain amount of errors normal?

[stomasko]

What kind of errors are you seeing? Please include a show run and show interface from each router to help check for problems.

Steve

[stomasko]

What kind of errors are you seeing? Please include a show run and show interface from each router to help check for problems.

Steve

[h.parsons]

I dont have a show run with me but it is a basic T1 using all timeslots, clock source internal, hdlc encapsulation. Here is a show interface

[egain.com]

hi

The interface information is for one week.

Both the side interface has input errors. It seems there could be some minor termination issue at provider side.

AS far as the interface resets count is zero , there should be negligible effect on the data traffic.

Hope this helps.

regards

Rakesh

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[stomasko]

While not a lot of errors, you shouldn't have any. Have you had the telco check the lines?

Steve

[gyalch]

Is the a full T1 or a frac?

I had a similar problem and removed the bandwidth definition from the the interfaces and let them use the default and that seemed to solve the problem. It looks like you bandwith is set at 1536 while a full T is 1544.

[timm.benkula]

Try looking at the results of this command:

show service-module serial 0/0

look for errors, mainly Errored Seconds and check periodically to see if they are incrementing. When I report problems to my provider, I always report the number of Errored seconds or what ever errors are showing.

Also, contrary to popular belief the bandwidth setting on an interface has nothing to do with the actual bandwidth of the interface. It used by certain routing protocols for routing calculations.

[jrahm]

Line clocking could be the problem. Is this a telco line? If so, clocking should probably be set to network on both sides, as most telcos provide timing. If there is no clocking on the line at all, then one side of your link should be set to network, and the other to internal.

Tim is absolutely correct on the bandwidth statement, this is strictly for metric calculation.

[Enes Simnica]

 **bleep**, I love T1 situations man. Great troubleshooting, fellas!

-Enes

[Joseph W. Doherty]

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@Enes Simnica wrote:

 **bleep**, I love T1 situations man. Great troubleshooting, fellas!

-Enes

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Hopefully, after 19 years (and change) their troubleshooting was successful.

[Enes Simnica]

Yeah...., but for real, very cool stuff. Devices like the MX2820, 2000, Hatteras HN devices, Tadiran devices, Tellabs, ONS devices, and many more are just great, and I had a great experience working with them... (in general from T1, T3-DS3) (even though they're old...)

-Enes

[Joseph W. Doherty]

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@Enes Simnica wrote:

Yeah...., but for real, very cool stuff. Devices like the MX2820, 2000, Hatteras HN devices, Tadiran devices, Tellabs, ONS devices, and many more are just great, and I had a great experience working with them... (in general from T1, T3-DS3) (even though they're old...)

-Enes

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Laugh, well I'm old too.  I've used 300 baud modems, RS232 terminals, 4 Mbps TR, 10 Mbps Ethernet (non-switched), DS0, DS1/ES1, DS3/ES3, and OC (possibly even up to OC-12, but so long ago, I'm unsure, plus OC-12 would have been uncommon for an Enterprise WAN), when they were all state-of-the-art.

I'm glad you enjoy troubleshooting them.  Of course, for real fun, you need to set up ISDN, including primary ISDN.

Anyway, with regard to OP's question, ". . . is a certain amount of errors normal?", yes and no.  Various technologies usually have a spec for allowable error rates.  Anything less than the allowed error rate is "normal", although often actual normal is below, sometimes well below, the allowable error rate.

[Giuseppe Larosa]

Hello @Joseph W. Doherty ,

>> Of course, for real fun, you need to set up ISDN, including primary ISDN

Yes, it was really difficult and we needed an ISDN switch to emulate an ISDN network to be able to test it. One of the most difficult setups was to make MPLS L3 VPN VRF access over ISDN BRI call to an ISDN PRI E1 on Cisco 7200 used as PE node,  using Radius authentication to get in AAA response packets as AV-pairs  the VRF< name > to which the calling customer should be associated.

To test multiple concurrent  ISDN calls to the same ISDN PRI E1 we needed to use a true ISDN central office setup.

For all these kinds of WAN technologies the most useful command was something like

show controller e1 0/0/0

Checking the number of SES Severly Errored Seconds in the last 24 hours was actually important. As it was important the clocking aspects.

Similar considerations for T3 aka DS3 or for E3, in Europe we have the SDH hierarchy so OC-3 is equivalent to STM-1 and so on.

For some years Packet over Sonet/SDH POS became the WAN standard for router to router connections going up to 10 Gbps links this was after the idea of using ATM for carrying IP traffic was put in standby for complexity and overhead. A POS interface was much simpler to implement then an ATM interface and the corresponding linecard or port adapter was cheaper then the ATM one.

Now, almost everything is over Ethernet and we have lost some in variety.

There are some parts like in IoT access where there are different OSI layer1/ OSI layer2 that we can still see something quite different.

Hope to help

Giuseppe

[Joseph W. Doherty]

My ISDN experience pales compared to yours.  I only had to work out what few of the zillion ISDN options I really needed.

For those who have never used ISDN, to me, the biggest difference was its so much, much faster dialing and call setup vs. analog.

Also a bit of fun, when setting up international links, DS1 being 1.544 Mbps and an E1 being 2.048 Mbps, or a DS3 being 45 Mbps and an E3 being 34 Mbps.  (Generic Traffic Shaping was handy even back then.)

Yes, much of wired WAN variety has been replaced by Ethernet, but we can still have fun with various wireless standards, and perhaps for various USB and Bluetooth standards too when used for some form of networking.  ; )