Why do Serial interfaces sometimes hang during E1 stream switching?

Hello,
We're working on your problem. Please be patient.

Hi friend!
According to the problem you described, I don't quite understand it. Can you give an example to illustrate your problem, for example, the interface at both ends cannot communicate with each other, or the interface at both ends is connected and the interface is not up.
If this is what I guess, can you feedback the configuration and display information of the interfaces at both ends?

Hello.

We have a lot of E1 channels, and we come across this problem very often. For example, we have 3 E1 streams between NE 8000 M6 routers grouped in mp-group, we also need to add an E1 channel. I configure the E1 controller and the Serial interface.

controller E1 0/5/7

 channel-set 1 timeslot-list 1-31

 undo shutdown

interface Serial0/5/7:1

 link-protocol ppp

 ppp mp Mp-group0/5/3

We make physical connections. Checking ...

dis controller E1 0/5/7

E1 0/5/7 current state : UP (ifindex: 32)

Last physical up time   : 2021-11-19 09:49:37+03:00

Last physical down time : 2021-11-19 09:49:37+03:00

Current system time: 2021-12-23 08:20:44+03:00

Physical layer is Packet Over NO-CRC4

clock master , linecode hdb3 , loopback none

impedance 120 ohms

Alarm: none

Bipolar Violation:           71

FAS Error Count:             0

CRC4 Error Count:            --


dis interface Serial0/5/7:1

Serial0/5/7:1 current state : UP (ifindex: 73)

Line protocol current state : DOWN

Route Port,The Maximum Transmit Unit is 1500, Hold timer is 10(sec)

Derived from E1 0/5/7, Timeslot(s) Used: 1-31, baudrate is 1984000 bps

Internet protocol processing : disabled

Link layer protocol is PPP

LCP stopped

CRC: CRC-32

Scramble disabled

Current system time: 2021-12-23 08:21:05+03:00

Statistics last cleared:2021-12-22 23:16:56+03:00

  Traffic statistics:

    Last 300 seconds input rate 33 bits/sec, 0 packets/sec

    Last 300 seconds output rate 67 bits/sec, 0 packets/sec

    Input: 2961468 packets, 1152178116 bytes

    Input error: 0 shortpackets, 1 longpackets, 63 CRC, 134 lostpackets

    Output: 2126267 packets, 626484277 bytes

    Output error: 0 lostpackets

    Output error: 0 overrunpackets, 0 underrunpackets

    Last 300 seconds input utility rate:  0.01%

    Last 300 seconds output utility rate: 0.01%

    

 Mp-group is Mp-group0/5/3

 ===========Sublinks status begin======

 Serial0/5/6:1 physical UP,protocol UP

 Serial0/5/7:1 physical UP,protocol DOWN

 Serial0/5/8:1 physical UP,protocol UP

 Serial0/5/9:1 physical UP,protocol UP

 ===========Sublinks status end========

 Bundle Multilink, 3 member, slot 5, Master link is Mp-group0/5/3

  0 lost fragments, 0 reordered, 0 unassigned, 0 interleaved,

 sequence 0/0 rcvd/sent

 The bundled son channels are:

     Serial0/5/6:1

     Serial0/5/8:1

     Serial0/5/9:1

There are no errors, but Serial and mp-group are not raised. We restart the board reset slot 5 and check.

dis controller E1 0/5/7

E1 0/5/7 current state : UP (ifindex: 32)

Last physical up time   : 2021-12-23 08:24:35+03:00

Last physical down time : 2021-12-23 08:24:35+03:00

Current system time: 2021-12-23 08:27:55+03:00

Physical layer is Packet Over NO-CRC4

clock master , linecode hdb3 , loopback none

impedance 120 ohms

Alarm: none

Bipolar Violation:           1

FAS Error Count:             0

CRC4 Error Count:            --


dis interface Serial0/5/7:1

Serial0/5/7:1 current state : UP (ifindex: 73)

Line protocol current state : UP

Route Port,The Maximum Transmit Unit is 1500, Hold timer is 10(sec)

Derived from E1 0/5/7, Timeslot(s) Used: 1-31, baudrate is 1984000 bps

Internet protocol processing : disabled

Link layer protocol is PPP

LCP opened, MP opened

CRC: CRC-32

Scramble disabled

Current system time: 2021-12-23 08:26:46+03:00

Statistics last cleared:2021-12-23 08:24:39+03:00

  Traffic statistics:

    Last 300 seconds input rate 157954 bits/sec, 62 packets/sec

    Last 300 seconds output rate 111725 bits/sec, 26 packets/sec

    Input: 16860 packets, 5342682 bytes

    Input error: 0 shortpackets, 1 longpackets, 0 CRC, 1 lostpackets

    Output: 7172 packets, 3779132 bytes

    Output error: 0 lostpackets

    Output error: 0 overrunpackets, 0 underrunpackets

    Last 300 seconds input utility rate:  7.96%

    Last 300 seconds output utility rate: 5.63%

    

Mp-group is Mp-group0/5/3

 ===========Sublinks status begin======

 Serial0/5/6:1 physical UP,protocol UP

 Serial0/5/7:1 physical UP,protocol UP

 Serial0/5/8:1 physical UP,protocol UP

 Serial0/5/9:1 physical UP,protocol UP

 ===========Sublinks status end========

 Bundle Multilink, 4 member, slot 5, Master link is Mp-group0/5/3

  0 lost fragments, 0 reordered, 0 unassigned, 0 interleaved,

 sequence 0/0 rcvd/sent

 The bundled son channels are:

     Serial0/5/6:1

     Serial0/5/7:1

     Serial0/5/8:1

     Serial0/5/9:1

And everything works right away. We tried to turn it off controller E1, interface Serial0/5/7:1 and then turn it on, but it didn't help, only restarting the board helps.

Hi,
As far as I know, you should restart the member interface after you add it into the MP-group interface. So, you don't need to reset the slot, but just shutdown and undo shutdown the member interface.

Resolved