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use TRACE to locate. Because the on-line users reach the maximum access number, so the VLAN users cannot acquire the Ip address

Publication Date:  2012-07-27 Views:  144 Downloads:  0
Issue Description

Version:MA.20-7141(It has no relation with version)
PC users acquire the addresses via DHCP,the users in one area share one VLAN.
Malfunction:the users cannot acquire IP addresses.

Alarm Information

Handling Process

The methods are involved to solve the problem, herein, we mainly use TRACE to settle it. As using Trace, if we can trace the packts,then the problem will be excluded; check the address to know the utilizing condition and exclude the possible reasons.
The detailed steps:
1、Because the usres share one VLAN, and they cannot use the user name to trace,but the MAC address to acquire the user MAC address.
2、Enable TRACE(under the system view, use trace enable)
3、Confirm the tracing target and input the tracing result into files(via trace object mac 00e0-4c81-1b2b out shinong.txt)
4、Save the tracing data(use save trace information
5、Via dir to check the tracing files and detect the file size is not 0,so we can exclude the possibility of circuity,then we analyze the tracing file(more shinong.txt) and detect “Fail to new conncetion for license or other access limit”,the information means the connecting number has already reached the maximum connecting number.
6、Via display static-user to check the ststic users and detect 1876 ones,via dis access-user domain default0 to check the current DHCP users and detect 164 ones,the total is:2040 ones. The maximum access number of MA5200F is 2K.
7、Delete the useless static ones, and the users can aquire the addresses normally.
8、Undo Trace function, and delete the output files.

Root Cause

the possible reasons may be:
1、The user circuity is error, the DHCP packets do not reach MA5200F
2、There are no the spare addresses in the address pool
3、The client end is error, the PC configuration or PC is error.
4、The user access number has already reached the maximum access number of MA5200F


1、We can solve the problems via many methods: capture packets, via debug info. But the packets acquired are too many, it is difficult to analyze. Trace can analyze detailedly for the detailed condition. The method is very useful and effective for the single problem.
2、MA5200F supports 2K on-line users, the static users occupy the entries no matter whether they are on line or not.