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?

[Enes Simnica]

I might still be in my 20s, but I’ve been fortunate enough to work with some pretty impressive equipment at an ISP, including some serious old-school devices. It’s funny how I almost forgot about OCs and SONET—those were some great times in the world of networking!

By the way, I consider "old" to be 100 years and up, so we're all still young here. Cheer up and keep pushing forward!

-Enes

[Joseph W. Doherty]

I've been trying to find the "spec" for T1 error rates, so far, without success.

An AI summary searching for "common t1 bit error rate" provides:

Typical T1 Bit Error Rates

While specific error rates may vary depending on the system and environment, here are some general guidelines:

• A good T1 line typically has a BER of 10^-6 or better.
• A BER of 10^-5 is considered acceptable for many applications.
• A BER of 10^-4 or higher may indicate a problem with the line or equipment.

However also searching on "typical t1 bit error rate" returns:

Typical t1 bit error rate

Based on industry standards and testing practices, the typical T1 bit error rate (BER) for a fault-free transmission line is extremely low, often quoted as:

• 10^-9 (1 error per 1 billion bits) or better

In other words, a T1 line with no defects or degradation should exhibit fewer than 1 bit error per billion bits transmitted.

For comparison, some common T1 bit error rates in real-world scenarios:

• New, installed T1 lines: 10^-10 (1 error per 10 billion bits) or better
• Well-maintained T1 lines: 10^-9 (1 error per 1 billion bits)
• T1 lines with minor degradation (e.g., due to aging or environmental factors): 10^-8 (1 error per 100 million bits)

Keep in mind that these values are general estimates and can vary depending on the specific transmission equipment, cable quality, and environmental conditions. In practice, T1 bit error rates are typically monitored and reported as a ratio, such as “1 in 1,000,000” or “1e-6,” which represents the number of errors per unit time (e.g., seconds or minutes).

Note: The provided information is based on the search results and does not include specific measurements or data from individual sources. The typical T1 bit error rate mentioned above is a general industry standard and may vary depending on the specific context and testing conditions.

[Giuseppe Larosa]

Hello @Joseph W. Doherty ,

refer to

https://www.ciena.com/insights/telecom-glossary

Errored Seconds (ES) A performance monitoring parameter. ES "Type A" is a second with exactly one error, ES "Type B" is a second with more than one and less than the number of errors in a severely errored second (SES) for the given signal. ES by itself means the sum of the type A and B ESs.

and

https://www.cisco.com/c/en/us/support/docs/wan/t1-e1-t3-e3/25540-t1e1-codes.html

this is more specific here you can find explanations of parameters shown in

show controller e1

or

show controller t1

The framing structure that is used creates the need for different type of error categories.

Hope to help

Giuseppe

[Joseph W. Doherty]

A very useful, and quick way, to get an approximate high level BER.  (The reason I write "approximate", believe its based on frames.)

I may have missed it, in either reference, but does either provide what's great, good or bad error rates?

When you get down to BER (normally a TelCo consideration), a BERT (test tool), can indicate what the cause of a problematic BER is (I think that's the case).

Even when everything is "perfect", there's no real guarantee of zero errors, but when you get up to rates at 10^-12, or better, errors are rather infrequent.

Given any particular expectation of a BER, for a specific bandwidth, you can calculate how often you might expect an error and translate to frames and/or packets based on their sizes.  (Understand, one disadvantage of larger frame/packet sizes, even a single bit error [w/o ECC] will corrupt the whole frame/packet.)

[Enes Simnica]

Also, everyone, I’m really glad I could bring us all together to chat about some classic devices and networks. It’s always great to dive into the old-school stuff with fellow enthusiasts!

-Enes