This is a CISCO document explaining NAT: http://www.cisco.com/warp/public/cc/pd/iosw/ioft/ionetn/prodlit/1195_pp.htm
It states that "Any TCP/UDP traffic that does not carry source and/or destination IP addresses in the application data stream" is supported and without the sendsize problem also amanda UDP traffic is supported. When port translation is configured, there is finer control over translation entry timeouts, because each entry contains more context about the traffic using it. Non-DNS UDP translations time out after 5 minutes; DNS times out in 1 minute. TCP translations time out after 24 hours, unless a RST or FIN is seen on the stream, in which case it times out in 1 minute. The problem exists certainly also with linux firewall using iptables becouse it uses even smaller timeouts. ----- Original Message ----- From: "Lee Fellows" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Wednesday, July 03, 2002 7:02 PM Subject: Re: syncronize backups > On Wed, 2002-07-03 at 10:47, Scaglione Ermanno wrote: > > thanks but I found the real problem: there is a cisco router doing NAT > > between the amanda server and the two server. I found that it had a nat udp > > timeout of 6 minutes (CISCO default). What happens is that amanda gets the > > estimates from the first server that answers and starts the backup on that > > server, then the link becomes too busy, the UDP connection with the second > > server times out on the router and the second backup doesn't work ...... > > Well we could consider this an amanda bug maybe, the problem is that amanda > > doesn't do keepalive while sendsize runs, and sendsize itself doesn't do > > keepalive. I have been told that most CISCO routers doing NAT have this 6 > > minutes nat udp timeout thus if the estimate takes more than 6 minutes the > > backup will probably fails if there is such a router in between ..... > > > > ----- Original Message ----- > > From: "Chris Marble" <[EMAIL PROTECTED]> > > To: "Scaglione Ermanno" <[EMAIL PROTECTED]> > > Sent: Wednesday, July 03, 2002 4:39 AM > > Subject: Re: syncronize backups > > > > > > > Scaglione Ermanno wrote: > > > > > > > > I have a strange problem with amanda, I am backing up 6 servers with the > > > > same disklist and 2 of them alternatively fails with a timeout in > > sendsize. > > > > Server A works for a couple of days and server B doesn't in the same > > days, > > > > then server B works and server A doesn't. I suppose the reason is that > > both > > > > server are behind a slow link. How can I tell Amanda not to backup > > > > simultaneously the two servers using 1 disklist? > > > > > > Hmm, I was going to tell you to lie to Amanda and tell it that all the > > disks > > > are on the same spindle. But then I realized that the spindle parameter > > is > > > on a per-machine basis. You could set an earlier starttime for those > > servers and > > > set inparallel to 1 just for a while. > > > -- > > > [EMAIL PROTECTED] - HMC UNIX Systems Manager > > > > > > > > > > Interesting. Do I understand your suggestion correctly to imply that > keepalive be done on udp sockets. If so, might I suggest that this > is not the solution. Its been several years since I programmed tcp > and udp clients and servers, but if memory serves me correctly, > keepalive is only available in the tcp-family of protocols. Keepalive > was intended to maintain an otherwise idle connection for some period > of time. Udp by definition is not a connected protocol and such an > option would be meaningless for it. > > > >
