NE40E version is V600R001C00SPC800, the topology is:STP1(CE1; IP:10.10.10.2/30)--NE40E(PE1 IP:10.10.10.1/30;QOS:AF4)---NE80E----NE40E(PE2;IP:10.10.10.5/30;QOS:AF4)—MSC2(CE2;IP: 10.10.10.6/30); The customer Core team complain that the communication between MSC1 and MSC2 do not work properly.
There is SCTP packets lost alarm at MSC
Because after version V6R1 the mark of all ICMP packets which are sent by MPU is CS6, so if we use normal ping from PE1 to PE2, we can not find any packets lost when the physical link do not have problem. If we use ping –tos 128(means AF4 ping)change the mark of packets we can find the drop, it means there is QOS drop somewhere in the network but not physical link problem.
Because the ICMP packets mark is different from CE and PE , we can use this rule to indentify whether this problem related to physical link problem or not, and find out the QOS drop.