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USG2100BSR serial port interconnect displays IPCP acksent

Publication Date:  2012-11-16 Views:  106 Downloads:  0

Issue Description

It is unable to carry on the business visiting after Usg2100BSR serial port interconnected

Alarm Information


Handling Process

In any view, execute “display interface serial” comman, check the upstream SA interface state information
Serial2/0/1 current state : UP 
Line protocol current state : UP
Description : Huawei, Secoway Series, Serial2/0/1 Interface
The Maximum Transmit Unit is 1500 bytes, Hold timer is 10(sec)
Internet Address is
Link layer protocol is PPP
LCP opened, IPCP acksent
Output queue : (Urgent queue : Size/Length/Discards)  0/50/0
Output queue : (Protocol queue : Size/Length/Discards) 0/1000/0
Output queue : (FIFO queuing : Size/Length/Discards)  0/256/0
Physical layer is synchronous,
Interface is DTE, Clock is DTECLK1, Cable type is V35
    Last 300 seconds input rate 17.58 bytes/sec, 1.10 packets/sec
    Last 300 seconds output rate 19.07 bytes/sec, 1.09 packets/sec
    Input: 463 packets, 7566 bytes
           0 errors:
           0 non octet_aligned, 0 abort sequence
           0 giants, 0 CRC, 0 overruns, 0 carrier lost
    Output:462 packets, 8240 bytes
           0 errors:
           0 underruns, 0 CTS lost errors
Link layer protocol is PPP
LCP opened, IPCP acksent denoted PPP protocol’s LCP level is up, and IPCP level is down. See from here, SA interface card’s physical layer is normal, cable interconnection is normal, should be the PPP negotiation parameters anomaly.
In any view, execute “interface serial xx” command, enter the upstream SA interface view, then execute the “display this” command, check SA interface’s PPP configuration.
[USG2160BSR-Serial2/0/1]dis this
interface Serial2/0/1
clock DTECLK1
link-protocol ppp
ip address
There are two commands needed to be configured, i.e., “undo PPP ipcp DNS request” and “undo PPP ipcp NBNS request”. After configured the two commands, problem is solved.

Root Cause

 Serial port interconnect, involves two aspects
2100 upstream wan 1SA or 2SA interface’s physical layer is up, the PPP link layer LCP is up and ipcp is down.
2100 upstream wan 1SA or 2SA interface’s physical layer is up, the PPP link layer LCP and ipcp are up. But the business is impassability.


When interconnecting the serial port, pay attention to view the port information.