Fragmentation WAN PPPoE
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Hi,
I'll try to explain my problem.
I've got a PPPoE connection with MTU 1492. Behind, a Nat 'Port forward" for an email server. Only one of our client can't send us big email. Small emails work correctly but if there is fragmentation some packets are dropped:
May 7 09:43:08 SFR 194.250.153.xxx 5.39.xxx.xxx TCP:
May 7 09:43:12 SFR 194.250.153.xxx 5.39.xxx.xxx TCP:
May 7 09:43:20 SFR 194.250.153.xxx 5.39.xxx.xxx TCP:
May 7 09:43:36 SFR 194.250.153.xxx 5.39.xxx.xxx TCP:
I tested many configuration:
- firewall optimization in conservative mode
- Disable hardware checksum offload
- Clear invalid DF bits instead of dropping the packets
- Disables the PF scrubbing option which can sometimes interfere with NFS and PPTP traffic
- disable net.inet.tcp.rfc1323
- disable net.inet.tcp.sack.enable
- set mtu 1492 on my server
I'm running pfsense 2.0.3 64b. I don't know why a can't get message from this peer. Could you help me please?
[packetcapture (16).txt](/public/imported_attachments/1/packetcapture (16).txt) -
Hi,
have no direct idea but you can test here your MTU and other helpful things:
http://www.speedguide.net/analyzer.php -
Hi,
Thank you for your answer.
In fact your site give me MTU 1460 and not 1492. I don't know why.TCP options string: 0204058c010303070402080a0006a9ea00000000
MSS: 1420
MTU: 1460
TCP Window: 66176 (NOT multiple of MSS)
RWIN Scaling: 7 bits (2^7=128)
Unscaled RWIN : 517
Recommended RWINs: 65320, 130640, 261280, 522560, 1045120
BDP limit (200ms): 2647kbps (331KBytes/s)
BDP limit (500ms): 1059kbps (132KBytes/s)
MTU Discovery: ON
TTL: 49
Timestamps: ON
SACKs: ON
IP ToS: 00000000 (0) -
Thank you for your answer.
In fact your site give me MTU 1460 and not 1492. I don't know why.MSS: 1420
MTU: 1460
MTU Discovery: ONgood thing seems that MTU discovery is on … can you see in your ppp logs what MTU is set by pfSense ?
Perhaps you must set for security MTU in PPP page directly (there is a field for it).But normally also many other sites should have problems when using more than 1500 Bits ... its quick reached ;)