E1 Slip Error Encountered

[ccg-collab1]

Hi,

We may seek your assistance regarding on the slip error we encountered. Currently we have 5 E1 ports/connection with two Telco Providers. The first two E1 connection are coming from Provider A and the remaining 3 are coming from  Provider B. We encountered this issue as follows:

1st Scenario. When we tried to configure  Provider A port 0/0/0 as the primary clocking source. We encountered slip errors from the port 0/1/0 ,0/1/1,0/2/0 which are Provider B E1 connections. From the Provider A E1 connection we don't find any slip errors from the 2 ports 0/0/0,0/0/1. 

2nd Scenario. When we tried to configure the Provider B port 0/1/0 as the primary clocking source, we encountered errors from the E1 Provider A port 0/0/0,0/0/1. No errors encountered from the E1's Provider B.

Question 1. Is this a normal behavior that we encountered  slip error if two provider running on the Voice gateway since they have different clocking domain?

Question 2. Or if its not, do you have any recommendations on how we resolve this slip errors encountered?

Please see below existing clocking configuration of our customer.

PID: VWIC3-2MFT-T1/E1 (Customer module used)

card type e1 0 0
card type e1 0 1
card type e1 0 2
!
no aaa new-model
clock timezone MNL 8 0
 --More--         !
network-clock-participate wic 0
network-clock-participate wic 1
network-clock-participate wic 2
network-clock-select 1 E1 0/0/0 (Provider A)
network-clock-select 2 E1 0/0/1 (Provider A)
network-clock-select 3 E1 0/1/0 (Provider B)
network-clock-select 4 E1 0/1/1 (Provider B)
network-clock-select 5 E1 0/2/0 (Provider B)

sample#show network-clocks
  Network Clock Configuration
  ---------------------------
  Priority      Clock Source    Clock State     Clock Type

     1          E1 0/0/0        GOOD            E1         
     2          E1 0/0/1        GOOD            E1         
     3          E1 0/1/0        GOOD            E1         
     4          E1 0/1/1        GOOD            E1         
     5          E1 0/2/0        GOOD            E1         
    10          Backplane       GOOD            PLL        

  Current Primary Clock Source
  ---------------------------
  Priority      Clock Source    Clock State     Clock Type

     1          E1 0/0/0        GOOD            E1 

Looking forward for your responds.

Thank you

[HARIS_HUSSAIN]

Hi,

This should not be an issue for voice calls, the slip will only result in slight blip in the audio.

You can try synchronizing the second port to the backplance i.e remove the command network-clock-select , so the the Port do not use the network clock instead uses the system clock.

If it is absolutely necessary to sycn them to different providers then they has to be in different clocking domain. What is your router model ?.

Refer below documents 

http://www.cisco.com/c/en/us/products/collateral/routers/2800-series-integrated-services-routers-isr/prod_white_paper0900aecd805b9915.html

http://www.cisco.com/c/en/us/support/docs/wan/tdm/116050-trouble-tdm-clocking-00.html#anc9

>>>Please rate and mark correct if found so. <<<<<<

[ccg-collab1]

Hi Haris,

We already did that. I tried to remove the command network clock select on the port 2 still slip errors are being seen.

Router Model: CISCO3945

[Aman Soi]

Hi,

Just look into discussion, if it helps

https://supportforums.cisco.com/discussion/11879381/t1-pri-errors

regds,

aman

[Aseem Anand]

Hi,

Can you please share the router details?

Aseem

[ccg-collab1]

Hi Aseem,

Here's the model of the router.

PID: CISCO3945

[ccg-collab1]

Hi Aseem,

Already tried the network clock independent command but still slip errors were observed.

Do you have still any ideas regarding on this slip errors?

Thank you

[Aseem Anand]

Hi,

You can use clock source line independent command. Refer to the link below:

http://www.cisco.com/c/en/us/support/docs/routers/3600-series-multiservice-platforms/8106-vwicmf-t1.html

Aseem

[ccg-collab1]

Hi Aseem,

During the troubleshooting, I cannot find clock source line independent command. Only I found clock source line, internal and bits. Is there any command we need to input first before we come up on that choices/command.?

Thank you

[Aseem Anand]

Remove network clock participate commands and then try again.

Aseem

[ccg-collab1]

Hi Aseem,

You mean I will configure first the network clock select before the network clock participate, right?

[mikeleebrla]

What model router is this? On the older (3X00,2X00) routers you can only have one 'clocking domain' per router. Meaning you cannot be synced to multiple carriers like you are attempting to do.  On newer routers (4XXX) each PRI card (NIM) can have its own clocking domain, however. 

From the link below:

http://www.cisco.com/c/en/us/td/docs/routers/access/4400/feature/guide/isr4400netclock.html

Synchronization between the NIM and the Router

Network synchronization is supported for Cisco Fourth-Generation T1/E1 Voice and WAN Network Interface Modules (NIMs) on the Cisco 4000 Series ISR, by using the network-clock synchronization automatic global configuration command. By default, this command is disabled and user must configure it on Cisco 4000 Series ISR. This command is made ineffective for a particular NIM if you use the no network-clock participation slot / subslot command. See
Example 3: Disabling and Enabling a Module from Participating in the Backplane Clock. This causes the NIM to have its own separate clock domain.

ETA---you can do it on the older models,, but you have to have a separate PRI network module (separate MOBO and separate DSPs.

[ccg-collab1]

Hi,

Thanks for the response.We have 3945 Router model. Did you mean that we cannot have two clocking domain on 3945 router model.? Right now, router setup has two E1 port with the same Provider A is currently designated on the same module VWIC3-2MFT-T1/E1 on WIC 0. The other 3 E1 ports are designated on the other two VWIC3-2MFT-T1/E1 on WIC 1&2 and has the same Provider B. Our current configuration of clocking is showing below:

network-clock-participate wic 0
network-clock-participate wic 1
network-clock-participate wic 2
network-clock-select 1 E1 0/0/0 (Provider A)
network-clock-select 2 E1 0/0/1 (Provider A)
network-clock-select 3 E1 0/1/0 (Provider B)
network-clock-select 4 E1 0/1/1 (Provider B)
network-clock-select 5 E1 0/2/0 (Provider B)

From the configuration above and what you stated, this means that the clocking configuration is not correct. Kindly advise.

Thank you so much

[mikeleebrla]

Did you mean that we cannot have two clocking domain on 3945 router model.

That is correct unless you happen to have the NM-HDV2-2T1/E1 module in it. This module basically has another MOBO, DSPs, etc so it's capable of creating another clocking domain on its own.

Another option would be for you to get one of your carrier's to get clocking from you, rather than you getting clocking from them (this would eliminate the need for your router to sync to two different clocking sources and thus needed two separate clocking domains).

Or you could upgrade to a 4000 series router. The 4000s use a completely different architecture for the PRI cards (NIMs). Each NIM has its own DSPs on the card itself, and thus can have its own clocking domain per card, not per router as with previous versions.

Another option would be to simply get another router and have one router to handle PRIs from carrier A, and another router to handle PRIs from carrier B.