Date: Sat, 04 Nov 2000 12:27:20 +1100 (EST) From: peter.jeremy@alcatel.com.au To: FreeBSD-gnats-submit@FreeBSD.ORG Subject: kern/22596: NFS can't handle asymmetric server routing Message-ID: <00Nov4.134926est.115201@border.alcanet.com.au>
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>Number: 22596 >Category: kern >Synopsis: NFS can't handle asymmetric server routing >Confidential: no >Severity: serious >Priority: medium >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Fri Nov 03 18:00:02 PST 2000 >Closed-Date: >Last-Modified: >Originator: Peter Jeremy >Release: FreeBSD 5.0-CURRENT i386 >Organization: Alcatel Australia Limited >Environment: Client: FreeBSD 5-CURRENT PRE_SMPNG Server: FreeBSD 5-CURRENT late August 2000 >Description: Given the following network configuration. If the server routes to the client via router-3 and the client attempts to NFS mount a filesystem via server-2, the mount will block indefinitely. +------+ -2 +------+ +------+ -1 | |------| | |client|------|router| |server| +------+ | |------| | +------+ -3 +------+ For example "mount server-2:/cdrom /cdrom" produces the following network packets: 12:16:32.119294 client-1.976 > server-2.111: udp 56 12:16:32.303056 server-2.111 > client-1.976: udp 28 12:16:32.305913 client-1.975 > server-2.111: udp 56 12:16:32.481473 server-3.111 > client-1.975: udp 28 12:16:32.488073 client-1.855771785 > server-2.2049: 40 null 12:16:32.652983 server-2.2049 > client-1.855771785: reply ok 24 null 12:16:32.656422 client-1.973 > server-2.111: udp 56 12:16:32.821607 server-3.111 > client-1.973: udp 28 12:16:32.831160 client-1.972 > server-2.1017: udp 124 12:16:33.111041 server-2.1017 > client-1.972: udp 68 12:16:33.180257 client-1.1718190197 > server-2.2049: 124 access fh 117,2/3 003f 12:16:33.421336 server-3.2049 > client-1.1718190197: reply ok 120 proc-135571692 12:16:33.422329 client-1 > server-3: icmp: client-1 udp port 971 unreachable The last 3 packets repeat indefinitely (with exponential backoff). When I change the routing on the server so packets for client-1 go via server-2 instead, it recovers and completes the mount: 12:17:44.046144 client-1.1718190197 > server-2.2049: 124 access fh 117,2/3 003f 12:17:44.247190 server-2.2049 > client-1.1718190197: reply ok 120 access c 0023 >How-To-Repeat: Set up network and issue mount command as per above. >Fix: Unknown. The client is correct to reject the packets from an (unknown) server. The server should be using a source address that matches the address that the client requested to mount. >Release-Note: >Audit-Trail: >Unformatted: To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-bugs" in the body of the message
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