On 2014-09-08 10:03, Benny Kurniawan Candra wrote: >> Kalau sender run dibelakang firewall memang terkadang gagal >> > kirim/terima >> > jika jalur koneksi antar kedua server sedang sibuk. >> > Mestinya sender akan retry to send, kalau saat itu jalur koneksi sedang >> > lebih lengang mestinya akan berhasil. >> > > Pak apakah harus ada settingan di mdaemon kami agar timeout bisa diperlama?
Ada di setting idle time out, akan tetapi tidak berpengaruh untuk penerimaan mail karena 1. Yang bertanggung jawab menghitung idle time out (dimulai sejak kapan) adalah sender host bukan receiver. 2. Penghitungan waktu idle time out menggunakan icmp protocol (ping) yang kalau di block (disalah satu sisi) tidak akan berjalan baik karena tidak ada response dari sisi yang lain. Ciri server yang run dibelakang firewall yang settingnya tidak baik, tidak bisa di ping. $ ping APAC01-HK1-obe.outbound.protection.outlook.com PING APAC01-HK1-obe.outbound.protection.outlook.com (207.46.51.119) 56(84) bytes of data. ^C --- APAC01-HK1-obe.outbound.protection.outlook.com ping statistics --- 5 packets transmitted, 0 received, 100% packet loss, time 4031ms 3. Dampak dari nomer 2 diatas adalah PMTUD (path maximum transmission unit discovery) menjadi tidak berjalan semestinya --> akan banyak terjadi retry to send tcp packet yang memperlambat koneksi --> time out. http://technet.microsoft.com/en-us/library/cc940069.aspx ICMP is a maintenance protocol specified in RFC 792 and is normally considered to be part of the IP layer. ICMP messages are encapsulated within IP datagrams, so that they can be routed throughout an internetwork. ICMP is used by Windows 2000 to: - Assist in PMTU discovery. http://en.wikipedia.org/wiki/Path_MTU_Discovery --- Path MTU Discovery (PMTUD) is a standardized technique in computer networking for determining the maximum transmission unit (MTU) size on the network path between two Internet Protocol (IP) hosts, usually with the goal of avoiding IP fragmentation. PMTUD was originally intended for routers in Internet Protocol Version 4 (IPv4).[1] However, all modern operating systems use it on endpoints. In IPv6, this function has been explicitly delegated to the end points of a communications session.[2] Problems with PMTUD Many network security devices block all ICMP messages for perceived security benefits,[6] including the errors that are necessary for the proper operation of PMTUD. This can result in connections that complete the TCP three-way handshake correctly, but then hang when data is transferred. This state is referred to as a black hole connection.[7] Some implementations of PMTUD attempt to prevent this problem by inferring that large payload packets have been dropped due to MTU rather than because of link congestion. However, in order for the Transmission Control Protocol (TCP) to operate most efficiently, ICMP Unreachable messages (type 3) should be permitted. A robust method for PMTUD that relies on TCP or another protocol to probe the path with progressively larger packets has been standardized in RFC 4821.[8] --- Singkatnya: Sabar saja menunggu mail tersebut diterima, atau minta ke pengelola mail domain sender untuk ganti mail hoster yang lebih perduli terhadap 'keselamatan mail" (message success to delivered) dibanding "keamanan mail" (message security). -- syafril ------- Syafril Hermansyah MDaemon-L Moderators, running MDaemon 14.5.0 Beta RC1 SP 4.5.0 Beta B Harap tidak cc: atau kirim ke private mail untuk masalah MDaemon. -- --[MDaemon-L]------------------------------------------------ Milis ini untuk Diskusi antar pengguna MDaemon Mail Server. Netiket: http://www.netmeister.org/news/learn2quote Arsip: http://mdaemon-l.dutaint.com Dokumentasi : http://mdaemon.dutaint.co.id Henti Langgan: Kirim mail ke MDaemon-L-unsubscribe [at] dutaint.com Berlangganan: kirim mail ke MDaemon-L-subscribe [at] dutaint.com Versi terakhir MD 14.0.3, SP 4.1.5, BES 2.0.2, OC 2.3.3, SG 3.0.1
