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Knowledge Base

After a Huawei AR2220 Router Replaces an MSR 3016 Router, Its Serial Interface Is Down

Publication Date:  2019-07-08  |   Views:  353  |   Downloads:  0  |   Document ID:  EKB1000089016

Contents

Issue Description

After a Huawei AR2220 router replaces anMSR 3016 router, the physical layer status and protocol layer status of its serial interface are Down.

Alarm Information

Remove the cable from the MSR 3016 router and connect it to the Huawei AR2220 router. Run the display interface brief command on the Huawei AR2220 router. The command output shows that both the physical layer status and protocol layer status of the serial interface are Down.

<Huawei> display interface brief 
PHY: Physical 
*down: administratively down 
(l): loopback 
(s): spoofing 
(b): BFD down 
^down: standby 
(e): ETHOAM down 
InUti/OutUti: input utility/output utility 
Interface                   PHY   Protocol  InUti OutUti   inErrors  outErrors 
Cellular0/0/0               down  down         0%     0%          0          0 
Cellular0/0/1               down  down         0%     0%          0          0 
GigabitEthernet0/0/0        down  down         0%     0%          0          0 
GigabitEthernet0/0/1        up    up        0.01%  0.01%          0          0 
GigabitEthernet0/0/2        down  down         0%     0%          0          0 
LoopBack1                   up    up(s)        0%     0%          0          0 
NULL0                       up    up(s)        0%     0%          0          0 
Serial4/0/0                 down  down         0%     0%          0          0 
Serial4/0/1                 down  down         0%     0%          0          0 
Serial4/0/2                 down  down         0%     0%          0          0 
Serial4/0/3                 down  down         0%     0%          0          0 
Serial5/0/0                 down  down         0%     0%          0          0 
Serial5/0/1                 down  down         0%     0%          0          0 
Serial5/0/2                 down  down         0%     0%          0          0 
Serial5/0/3                 down  down         0%     0%          0          0 
Serial6/0/0                 down  down         0%     0%          0          0 
Serial6/0/1                 down  down         0%     0%          0          0 
Serial6/0/2                 down  down         0%     0%          0          0

Handling Process

Step 1 Check whether the cable works properly.

Remove the cable from the Huawei AR2220 router and connect it to the MSR 3016 router. Run the display interface brief command on the MSR 3016 router. The command output shows that the serial interface of the MSR 3016 router is Up and communicates with the remote interface properly. Therefore, the cable works properly.

Step 2 Check whether the card on the Huawei AR2220 router works properly.

Check the card status. The card works properly. After the card is removed from the slot and installed into another slot, the serial interface is still Down.

Step 3 Check whether the configuration is correct.

Compare the configuration of the MSR 3016 router with that of the Huawei AR2220 router.

MSR 3016:

interface Serial5/0:0 
description TO ShenZhenFenBu PDC53289887G 
link-protocol ppp 
firewall packet-filter 3010 inbound 
ip address 10.65.252.2 255.255.255.252

Huawei:


interface Serial4/0/0 
link-protocol ppp 
description TO ShenZhenFenBu PDC53289887G 
ip address 10.65.252.2 255.255.255.252 
traffic-filter inbound acl 3010 
#

The comparison result shows that the configuration of the Huawei AR2220 router is correct and is the same as that of the MSR 3016 router, but the serial interfaces of the two routers work in different modes.

 The serial interface of the MSR 3016 router is Serial5/0:0, indicating that the CE1/PRI interface works in E1 mode. In this mode, the CE1/PRI interface works at the rate of 2.048 Mbit/s without timeslot division.

 The serial interface of the Huawei AR2220 router is Serial4/0/0, indicating that the E1-F interface works in framed mode by default. In this mode, the E1-F interface works at the rate of N x 64 kbit/s (N is the number of timeslots bundled into a channel) and its transmission line is divided into 32 timeslots. The default rate of the E1-F interface in framed mode is 1.984 Mbit/s.

Step 4 In the serial interface view of the Huawei AR2220 router, configure the E1-F interface to work in unframed mode. In this mode, the E1-F interface works at the rate of 2.048 Mbit/s without timeslot division.

<Huawei> system-view
[Huawei] interface serial 4/0/0
[Huawei-Serial4/0/0] fe1 unframed

After the configuration is complete, the serial interface of the Huawei AR2220 router is Up and communicates with the remote interface properly.

----End

Root Cause

The serial interfaces of the MSR 3016 router and Huawei AR2220 router work in different modes. Therefore, after the Huawei AR2220 router replaces the MSR 3016 router, its serial interface is Down and fails to communicate with the remote interface.

Suggestions

When replacing an router with a Huawei router or connecting a CE1/PRI interface to an E1-F interface, make sure that the CE1/PRI interface and E1-F interface work in the same mode.