VFR-4-FRAG_TABLE_OVERFLOW error messages on tunnel interface

[CiscoMedMed]

On my Cisco 3945 router which is serving as a DMVPN main hub - I am seeing these frag table overflow messages a few times a day. Can they seriously impact performance for the people at the spoke sites? If I increased the frag table what would be a good value? I see up to 1024 is permitted.

354919: .Feb 26 16:28:25.299 PST: %IP_VFR-4-FRAG_TABLE_OVERFLOW: Tunnel1: the fragment table has reached its maximum threshold 16
354920: .Feb 26 16:37:32.309 PST: %IP_VFR-4-FRAG_TABLE_OVERFLOW: Tunnel1: the fragment table has reached its maximum threshold 16
354926: .Feb 26 16:59:34.310 PST: %IP_VFR-4-FRAG_TABLE_OVERFLOW: Tunnel1: the fragment table has reached its maximum threshold 16
354927: .Feb 26 17:18:39.311 PST: %IP_VFR-4-FRAG_TABLE_OVERFLOW: Tunnel1: the fragment table has reached its maximum threshold 16
354928: .Feb 26 17:38:47.316 PST: %IP_VFR-4-FRAG_TABLE_OVERFLOW: Tunnel1: the fragment table has reached its maximum threshold 16
354934: .Feb 26 20:15:17.248 PST: %IP_VFR-4-FRAG_TABLE_OVERFLOW: Tunnel1: the fragment table has reached its maximum threshold 16
354969: .Feb 27 11:44:44.559 PST: %IP_VFR-4-FRAG_TABLE_OVERFLOW: Tunnel1: the fragment table has reached its maximum threshold 16
354970: .Feb 27 11:51:43.563 PST: %IP_VFR-4-FRAG_TABLE_OVERFLOW: Tunnel1: the fragment table has reached its maximum threshold 16
354971: .Feb 27 11:53:09.563 PST: %IP_VFR-4-FRAG_TABLE_OVERFLOW: Tunnel1: the fragment table has reached its maximum threshold 16
354972: .Feb 27 12:07:17.568 PST: %IP_VFR-4-FRAG_TABLE_OVERFLOW: Tunnel1: the fragment table has reached its maximum threshold 16
354973: .Feb 27 12:19:22.572 PST: %IP_VFR-4-FRAG_TABLE_OVERFLOW: Tunnel1: the fragment table has reached its maximum threshold 16
354975: .Feb 27 12:26:25.569 PST: %IP_VFR-4-FRAG_TABLE_OVERFLOW: Tunnel1: the fragment table has reached its maximum threshold 16
354976: .Feb 27 12:58:50.575 PST: %IP_VFR-4-FRAG_TABLE_OVERFLOW: Tunnel1: the fragment table has reached its maximum threshold 16
354982: .Feb 27 15:15:34.616 PST: %IP_VFR-4-FRAG_TABLE_OVERFLOW: Tunnel1: the fragment table has reached its maximum threshold 16
354984: .Feb 27 15:30:20.618 PST: %IP_VFR-4-FRAG_TABLE_OVERFLOW: Tunnel1: the fragment table has reached its maximum threshold 16
354985: .Feb 27 15:37:34.622 PST: %IP_VFR-4-FRAG_TABLE_OVERFLOW: Tunnel1: the fragment table has reached its maximum threshold 16

[Francesco Molino · Accepted solution]

Hi

Fragmentation could have a performance impact.
Sometines, for some traffic, you can't about getting fragmentation.
This happens if a device somewhere in the middle has a lower mtu than expected. Have you validated that you gave all interfaces in the path with the correct mtu.