One more question: Why this only affected hosts behind the firewall, not the firewall itself?
Please refer to RFC 1191 - Path MTU Discovery.
-- Wenzhuo Zhang <wenzhuo@xxxxxxxxxx> GnuPG Key ID 0xBA586A68 Key fpr: 89C7 C6DE D956 F978 3F12 A8AF 5847 F840 BA58 6A68