Hi All.
Dear experts during EPSFB from 5G to 4G can high GTP loss on target 4G site lead to EPSFB failure?
Mainly YES, but it depends on the GTP-U/MPLS link structure. In a typical network, there are usually one or two high-capacity links (e.g., 100G) and four to six lower-capacity links (e.g., 10G). If a high-capacity link becomes heavily utilized, traffic is dynamically switched to the lower-utilized links. Once the load decreases, traffic switches back to the main links.
However, if there is delay or latency during this switching, it can directly impact signaling, bearer establishment, timeouts, and retransmissions. If high GTP loss occurs, it can lead to severe deterioration in network performance, affecting EPS Fallback, voice/data continuity, and overall service quality.
Recently, I was troubleshooting an EPSFB case for a VIP user.
Based on the analysis, it was observed that the target 4G site had a high GTP loss.
Apart from this issue, no other anomalies were found at the target site.
It’s possible that when the customer experienced the issue, a temporary problem occurred.
There might have been ongoing work on the link at that time.
Additionally, temporary network saturations can sometimes occur during rainy weather.