sundance-communications.com/forum Forums Wiring - Telecom Carriers - Trunks & Services T1's, CSU's and DSU's Adtran CSU Time Sync

Hey Coral or others,

I have 4 PRIs connected to 4 Adtran CSU Ace's (4th_gen). On the other end of the CSU's (TI side)I have Tandberg Video Conferencing equipment which has the capability of picking up a NTP (Network Time Protocal) on the LAN for a time stamp in logs and communication. My question is how does the Adtran CSU Ace pickup it's timing from the CO, and would the NTP time conflict with the time from the CO (as time slip)?
THX a Great Deal....Ark

We are using the B8Zs line code. :rolleyes:

I would think that the timing for the circuits and NTP have nothing to do with each other.

NTP is for "time" as in "Timex Time" or "What time is it?" time. Usually useful for logging and that's pretty much it. (As you already stated above)

T1 clock source timing is a whole different beast.

I'm glad you understood the question Majestic, thanks for clearing it up.

Here's a quick tidbit about NTP:

The Network Time Protocol (NTP) is a protocol for synchronizing the clocks of computer systems over packet-switched, variable-latency data networks. NTP uses UDP port 123 as its transport layer. It is designed particularly to resist the effects of variable latency (Jitter).

NTP is one of the oldest Internet protocols still in use (since before 1985). NTP was originally designed by Dave Mills of the University of Delaware, who still maintains it, along with a team of volunteers.

More found: https://en.wikipedia.org/wiki/Network_Time_Protocol

Good info, Majestic.

Ark, it's not difficult to confuse the two separate timings, or to think that they could conflict each other, but like mentioned, two completely separate beasts.

When it comes to the two types of timing, CSU/DSUs are like bridges. They have one timing interface in telco territory [Master/Slave..T-Carrier..from the CO..also referred to as "loop" timing] and one interface in data-communications territory [your NTP, or SNTP where high accuracy timing is not required.]

I noticed your mention of "timing slip":

In your master/slave timing, and like you mentioned, your CSU/DSU takes its timing from your CO. In most cases, your telco will supply timing because the entire telco network must operate with unified timing to deliver the T1/PRI circuits. Imperfect timing conditions will cause these slips [also called change of frame alignment / COFA errors], usually forcing the network equipment to either replicate or even delete data.

One very important rule to prevent the "timing slips":

There must be one clock source for synchronous networks. Free-running clocks at both ends of a circuit will corrupt data as the two clocks drift in and out of synchronization. If two CSU/DSUs are both operating in slave mode [no clock source], each will look to the other as the source of timing information. Any changes in the timing of one CSU/DSU will affect the partner because both CSU/DSUs are attempting to lock on to the timing information supplied by the other.

Sorry to get on a ramble like that, but we just want to help clarify the two different timings.

By the way..Welcome to the board, Arkangel!

You know, you guys are great!
Here is the skinny:
I have the 4 pri's going to their individual Adtran CSU's. 2 of the CSU's go to 1 Tandberg Gateway and the other two go to my second Tandberg Gateway. Each Gateway gives me an option to group the pri's as one so that the search for the DID numbers are reference appropriately. When the DID is referenced my other component (Tandberg Gatekeeper) allows the call to be sent or received by VTC codec associated to the DID number (10 rooms).
The codecs and the Tandberg Gatekeeper has the ability to pick up a NTP time stamp for communication between one another, and also the time is displayed on the plasma screen that is connected to the codec. The NTP IP is picked up from our local LAN off the switch that connects all of my equipment.
I know this sound complicated to follow,however I believe the NTP time has nothing to do with the timming of the CSU's and the Central Office time for the T1's, just as your post states.
The reason I bring all this up is ounce in a while my 4 CSU's would recieve enough errors to have themselves reboot dropping all my calls. The Telco keeps stating that it's my equipment, and I have no proof stating otherwise besides the error logs that they say are not understood by them (AIS, Code, Bipolar, CVS).
The Adtrans that I have are fairly new and have no option to choose a time source (internal,external or loop).
So that is current mission, to prove that the time from the t1's end, or loop at the CSU's and not traverse past them to other components.

By the way thanks for the welcome sign. I'm privileged to find a forum with great tech savvy cats such as yourselves. THX

ARK.........

Hrmmm...the aces had dipswitches back in the day. Are they the same? If so, there should be an option to select framing, coding, timing, etc. If you are getting that many errors the T1 could be bad. Remember, the errors are errors you are receiving from the circuit. This could be from numerous sources.

I would have the circuit tested.

Also, are you absolutely sure that the Ace is "rebooting" or is the T1 dropping causing all calls to fail. How do you know the ACE is rebooting?

In addition to Majestic's question, regarding this "rebooting", how often is "once in a while?"

Here is the knee jerker,

A few months ago I could sit and watch the CSU's drop and error, than my equipment drops and errors and all of them come back up right on schedule. It first starts with the CSUs however, we had brought the telecoms engineers in a meeting with our engineers and found that we where experiencing glare issues. So we had changed our equipment to hunt for B channels from low to high and the CO from High to low. This appeared to fix the drops, but every 2 to 3 weeks we find errors on the CSU's which drop all of are calls. Sometimes they would error out ounce a week for two consecutive weeks than run for 2 to 3 weeks straight with no errors. The times of the errors are normally 15 minutes to 2 hours apart.
The Adtrans we have are:
ESF T1 CSU 4th Generation
P/N: 1204025L1

The configuration is as follows:

Adtran CSU 107 REV C REV 0.0
Utility Address: 0002

Main/Config/Network NI

1: Format: ESF
2: Code: B8ZS
3: Yellow Alarm: Enabled
4: XMIT PRM: Off
5: Keep Alive: Unframed
6: BIT Stuffing: DISA
7: SET LBO: 0.0
8: Net LB: ENAB
9: ROB BIT SIG: DISA
10: RBS Start: 01
11: RBS END: 24

Main/Config/Unit/

Control Ports:
1: Modem Init: DISA
Data Rate: 9600

2: Alarms:
Traps: DISA
Output: Direct
TEL NUM:

3: Terminal (T1):

Format: ESF
Code: B8ZS
SET LBO: 0-133 FT

I did not see a timing config on these units.

Oh ya, I just got a call from SBC stating that they are not supplying the timing on my T1 line. Well while retaining my balance in my office chair I don't see how T1's can function without it. I do believe since these Adtran's do not have timing control, they have to be set to loop. Sound correct?

Do you have these PRIs setup for NFAS? (https://en.wikipedia.org/wiki/NFAS) If I missed that somewhere please forgive me. If you do and the T1 that is taking errors or dropping is the one with the D channel on it, that's not helping you much either.

As for what SBC tells you, I'm finding that pretty hard to swallow my friend. If the circuit is going through a 3/1/0 dacs somewhere, it's giving you timing. The only case that I am pretty sure you can't get timing is from a Titan5500 dacs (something about it not being able to deliver timing???) but I can't recall the exact reason why.

I've ALWAYS set my routers and CSUs to time off of the T1/Loop/Telco/Network. Just something I've never really put more thought into.