This is the device-wide count of user messages that had to be split into multiple SCTP chunks because they exceeded the path MTU. A nonzero and growing count on a link meant to carry small SS7 messages suggests either an unusually large signaling payload, such as a bulky M3UA message, or a smaller-than-expected path MTU, both adding reassembly overhead and a small chance of failure if a fragment is lost. This counter climbing right after a network change that lowered the effective MTU, such as adding a new tunnel hop, would point to that change as the cause of newly fragmented messages.