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The Broadcast Packets Cause the 678 Error for the User Dialup Through Certain Modems Connected to the MA5600 After the Cutover

Publication Date:  2012-07-25 Views:  34 Downloads:  0
Issue Description
Before the cutover: MA5200G-----MA5600-----modem----PC (each port of the MA5200G is connected to one MA5600)
After the cutover: MA5200G-----S7802 (convergence switch)-----MA5600 (multiple)-----modem-----PC
Before and after the cutover, the data on the MA5600 is the same, and two PVCs are configured on each port of the MA5600
8 /46(smart vlan19) E8-2 management vlan
0/35(stacking vlan 1225 ) E8-2 PPPOE service vlan
Before the cutover, the modem in the bridge mode of the A Company works normally and the user can go online through the modem dialup. After the cutover, the user fails to go online through the dialup with the modem of the A company, with the 678 error displayed. Other modems on the same port work in the normal state. 
 
Alarm Information
The 678 error is displayed through the dialup on the PC. 
Handling Process
1. Check the data of the MA5200G. It is found that the data is correct.
2. Check the condition that the S7802 learns the MAC address of the PC.
Modem of the A company:
<MinHe_S7802>dis mac-address 0040-d06e-c3b7
MAC ADDR                  VLAN ID STATE    PORT INDEX AGING     TIME(s)
0040-d06e-c3b7 19    Learned                    Ethernet3/0/3             AGING
Huawei’s modem:
MinHe_S7802>dis mac-address 0040-d06e-c3b7
MAC ADDR                VLAN ID STATE      PORT INDEX AGING    TIME(s)
0040-d06e-c3b7 19        Learned              Ethernet3/0/3             AGING
0040-d06e-c3b7 1220   Learned               Ethernet3/0/3             AGING
It is found that the 678 error is displayed because the S7802 learns the MAC address of the PC connected to the modem of the A company, and the MAC address corresponds to VLAN 19.
3. Check the condition that the MA5600 learns the MAC address of the PC. The condition is the same as that displayed in step 2. After PVC 8/46 carrying the E8-2 service is deleted on the MA5600, reset the modem. It is found that the dialup on the PC is in the normal state. In addition, query the learning of the MAC address of the PC on the MA5600. The information is displayed as follows:
QHHD-MHSN-MA5600(config)#display mac-address adsl 0/0/0
-----------------------------------------------------------------------
Type              MAC         MAC Type         F/S/P      VPI        VCI       VLAN ID
-----------------------------------------------------------------------
adl   0040-d06e-c3b7 dynamic            0/0/0        0         35         1220
-----------------------------------------------------------------------
Total: 1
It is found that the fault occurs because the modem of the A company is a single-PVC modem and the modem learns PVC 8/46 with the VLAN 19 tag by mistake.
4. By the careful analysis of the networking before and after the cutover, it is found that before the cutover, the E8-2 services with the VLAN 19 tag of different MA5600 devices are terminated on different ports of the BAS; after the cutover, the E8-2 services with the VLAN 19 tag of all the MA5600 devices are terminated on the same port of the BAS within one broadcast domain. On any port of any MA5600, after the modem of the A company receives the PADI packets with the VLAN 19 tag from other MA5600 devices, the PVC automatic search function is enabled, and it is determined that the PVC of the modem of the A company is PVC 8/46. The modem of the A company is a single-PVC modem, so when the PVC is determined to be PVC 8/46, other PVCs (including PVC 0/35 for Internet access through dialup) are deactivated by the modem. In this case, the 678 error occurs when the user connected to the modem of the A company goes online through dialup.
5. There are four ways to solve the problem:
1) Replace the single-PVC modem of the A company with the multi-PVC modem.
2) Delete PVC 8/46 on the DSLAM device. The modems that do not provide the E8-2 services are in the bridge mode, so only PVC 0/35 is needed for the dialup.
3). Enable the port isolation on the S7802 to prevent the broadcast.
4). Re-plan the data, and ensure that the E8-2 management VLAN 19 of each DSLAM device is labeled with the service VLAN to prevent the broadcast. 
 
Root Cause
After the cutover, the sub-port is re-planned only on the MA5200G. That is, VLANs are transparently transmitted on the S7802. Therefore, it is possible that the fault is caused in the following conditions:
1. On the MA5200G, the configuration of the inner VLAN of the QinQ VLAN is incorrect, or the range of the inner VLAN is small.
2. The network planning of the S7802 is incorrect. 
 
Suggestions
Null

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