Ethernet Loop In microwave and SDH affects several BTS
HI Dear Members ,
Here I want to share an experience with you , It is about a Loop problem happened between Microwave and SDH systems affected several BTS .
Description
-The Mobile service provider complained , that 3 sites (BTS)s working in Etherent (with out VLANs) have dropped suddenly while adding the 3rd BTS to the service .
- as transmission service provider we give the Mobile company Giga Ethernet ports from OSN 7500-EGS4 at the BSC site and then we undertake the forwarding the ethernet signal to the BTS sites , theses 3 sites were connected to the same destination SDH OSN 500 site but in separated ethernet ports , then they get connected to MICRWAVE toward the last destination as the following diagram :-
Solution / Conclusion:
After diagnosing the problem we found :-
1-that the microwave system combines all ethernet ports in a Switch and depends on forwarding based on MAC , before sending them to the BTS final Sites .
2-in the OSN7500 EGS4 board the LAN (HUB/Spoke ) setting were the default HUB for the main port and for all the VCTRUNKs.
- That caused a loop because ethernet signal was in switch in the microwave and also in a switch like in SDH
The solution was by setting LAN (HUB/Spoke) as HUB for the main Giga ethernet port in OSN 7500 and setting all VCTRUNK as spoke , Setting the port as HUB and VCTRUNCKS as spoke allows all branches to communicate with the main port , and doesn’t allow any branch to communicate with other branches , so it separates branches and prevent loops .
I hope to be useful for you
