Meaning of "received broken Microsoft ID: FRAGMENTATION"

[thomask121]

I successful installed ipsec-tunnels between three pfSense-boxes (1.2.3-RELEASE).

In IPSec VPN log I see repeating these messages :

Feb 2 19:25:14 racoon: [Site-A]: INFO: ISAKMP-SA established 192.168.2.4[500]-94.xxx.xxx.xxx[500] spi:2a5ef60dc6fxxxxx:c2216c2942xxxxxx
Feb 2 19:25:14 racoon: NOTIFY: couldn't find the proper pskey, try to get one by the peer's address.
Feb 2 19:25:14 racoon: WARNING: No ID match.
Feb 2 19:25:14 racoon: INFO: received Vendor ID: DPD
Feb 2 19:25:14 racoon: INFO: received broken Microsoft ID: FRAGMENTATION

Is there something I have to worry ?

What is "received broken Microsoft ID: FRAGMENTATION" telling me ?
Should I change the WAN MTU settings ?

To which ID is "WARNING: No ID match." referring ?

Thanks for your advice.

[pfSenseless]

Same here. Would love to know what it means, even if it is benign.