Networking:ME60-（Eth－tunrk 4）S9306（1/0/11）-(G 0/0/4)S3352(G 0/0/3)-MA5680-MA5620
Sometimes the onu linked with S9306 can not access internet ,nor communicate with gateway in the way of ping.Capture and analyze the packet, we find:( I). The upstream is normal. (II).The downstream from Me60 to S9306 has two tags( III). The packet received in S3352 has only one tag. The service is interrupted.
This case happens with some precondition:(i)The common board works with the enhanced board(ii)The data stream is from the common board to enhanced board(iii)The common board is set as vlan stack/dot1p-tunnel or traffic policy with vlan added(iv)The vlan mapping is configured in the port of common board(v)The packet from enhanced board matches the vlan mapping filter.
Result: The inner tag will be deleted while the outer tag remains to perform the vlan mapping function.So the packet will be sent to the next equipment with one tag.In this case, the configuration in S9306 meets the precondition referred before.The uplink is eth-trunk 4 which containes g1/0/0,g1/0/16, g4/0/23 ;The downlink port is g1/0/11.The slot 1 is intalled with common board while slot 4 is installed with enhanced board.When the packet arrvies at S9306 in g4/0/23 located in enhanced board(slot 4), it has two tags .Then,the packet will be forwarded to the dowlink port g1/0/11 located in the common board(slot 1) and delete the inner tag.Thus,S3352 can receive only one tag. The service is interrupted.
In S9306.there are some problems if the common board works with enhanced board.When the port in common board is set as the mode of vlan stack/dot1p-tunnel or traffic policy with vlan added, and the vlan mapping is configured in this port,the packet from enhanced board with two tags will be stripped of the inner tag if the packet matches the vlan mapping filter.The reason is that (i)The port of common board will be set as UNI when it works in stack/dotip-tunnel mode.(ii)For UNI,the packet from enhanced board to common board supports only one tag when it processes the vlan mapping function.As a result,the inner tag will be deleted while the outer tag remains to perform the vlan mapping function.
Suggestion: (i)Upgrade the common board in slot 1 to enhanced board(ii)Configure the service in the same board in slot 1 in case the upgrading is difficult to realize.