Hello, I have such network topology:
+--------+ +--------+ +--------+ | Server |<---- MTU 1500 ---->| Router |<---- MTU 1476 ---->| Client | +--------+ +--------+ +--------+ Server is box with FreeBSD 4.5-RELEASE, it have firewall, but for testing purpose all connections are allowed. Below is part of dump of session between client & server: 14:06:33.307163 client.1371 > server.7: S [tcp sum ok] 17372427:17372427(0) win 16384 <mss 1460> (DF) (ttl 61, id 28157, len 44) 14:06:33.307235 server.7 > client.1371: S [tcp sum ok] 3046898158:3046898158(0) ack 17372428 win 65535 <mss 1460> (ttl 64, id 11786, len 44) 14:06:33.365432 client.1371 > server.7: . [tcp sum ok] 1:1(0) ack 1 win 17232 (DF) (ttl 61, id 28158, len 40) 14:06:33.395645 client.1371 > server.7: . 1:1437(1436) ack 1 win 17232 (DF) (ttl 61, id 28159, len 1476) 14:06:33.395889 server.7 > client.1371: P 1:1437(1436) ack 1437 win 65535 (DF) (ttl 64, id 37650, len 1476) [...skip...] 14:06:48.477578 server.7 > client.1371: . 1437:2897(1460) ack 10001 win 65535 (DF) (ttl 64, id 25428, len 1500) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Server send packet with size 1500 bytes 14:06:48.682558 router > server: icmp: client unreachable - need to frag (mtu 1476) for server.7 > client.1371: [|tcp] (DF) (ttl 61, id 25428, len 1500) (ttl 253, id 2491, len 56) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Router say to server that he must to decrease packet size 14:07:04.477857 server.7 > client.1371: . 1437:2897(1460) ack 10001 win 65535 (DF) (ttl 64, id 52781, len 1500) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ But server ignore this information and still send 1500 bytes packets [...skip...] It demonstrate that server _must_ to decrease MTU, but it doesn't. Wy? And how I can fix this problem? -- Sincerely, e-mail: [EMAIL PROTECTED] Alexey Luckyanchikov To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-net" in the body of the message
