Problems with large files over PPTP


#1

Hello,

We have been running our Balance One for about a month now. We use VPN over PPTP, utilizing the built-in Mac OS client, while Balance One is the PPTP server.
The bandwidth on the server side is usually well above 5mbps outbound, no complaints.

No issues over our LAN, only VPN from remote location. Also, no problem when accessing our public address from behind our network.

Our design software which uses specific ports works great, and is able to perform the required tasks and communicate with the server behind our firewall, until it has to occasionally download large files (anything over 500-700MB but it comes up to 1.4GB at times). Connection over VPN becomes unresponsive after 5-10 minutes of transfer and the software eventually reports timeout and broken connection to server. Similar things happen with large file transfers over VPN – the server remains mostly unresponsive until the transfer comes through. It almost feels that large file transfers over PPTP eventually choke the other traffic. VPN tunnel remains open, but applications are struggling to sustain live connections. Small chunks of data work very well in the same setting – we can easily work with projects that are up to 50MB.

NOTE: I suspected client-side bandwidth throttling issues, but their ISP support stated that this was not the case and even enabled hi-speed over 50mbps for testing, which did not help.

What are we doing wrong? Is there a way to limit PPTP bandwidth per client to allow some clear overhead, without affecting our LAN speeds?

Any suggestions?

====

This is an excerpt from Mac client ppp.log file (public IP manually X-ed out):

Thu Nov 20 09:45:56 2014 : PPTP connecting to server 'XX.XX.XXX.XXX' (XX.XX.XXX.XXX)…Thu Nov 20 09:45:56 2014 : PPTP connection established.
Thu Nov 20 09:45:56 2014 : PPTP set port-mapping for en0, interface: 4, protocol: 0, privatePort: 0
Thu Nov 20 09:45:56 2014 : Using interface ppp0
Thu Nov 20 09:45:56 2014 : Connect: ppp0 <--> socket[34:17]
Thu Nov 20 09:45:59 2014 : MPPE 128-bit stateless compression enabled
Thu Nov 20 09:46:01 2014 : local  IP address 192.168.20.96
Thu Nov 20 09:46:01 2014 : remote IP address 192.168.20.253
Thu Nov 20 09:46:01 2014 : primary   DNS address 192.168.20.253
Thu Nov 20 09:46:01 2014 : secondary DNS address 192.168.20.253
Thu Nov 20 09:46:01 2014 : pptp_wait_input: Address added. previous interface setting (name: en0, address: 192.168.0.11), current interface setting (name: ppp0, family: PPP, address: 192.168.20.96, subnet: 255.255.255.0, destination: 192.168.20.253).
Thu Nov 20 09:46:01 2014 : PPTP port-mapping update for en0 ignored: VPN is the Primary interface. Public Address: XXXXXXXX, Protocol: None, Private Port: 0, Public Port: 0
Thu Nov 20 09:46:01 2014 : PPTP clearing port-mapping for en0
Thu Nov 20 09:55:26 2014 : Protocol-Reject for unsupported protocol 0x3c04
Thu Nov 20 09:55:27 2014 : Protocol-Reject for unsupported protocol 0xaf
Thu Nov 20 09:55:27 2014 : Protocol-Reject for unsupported protocol 0xe0e5
Thu Nov 20 09:55:27 2014 : Protocol-Reject for unsupported protocol 0x49
(repeated)
Thu Nov 20 10:04:11 2014 : Protocol-Reject for unsupported protocol 0x5c11
Thu Nov 20 10:04:12 2014 : Protocol-Reject for unsupported protocol 0x8b
Thu Nov 20 10:04:13 2014 : Protocol-Reject for unsupported protocol 0x12c0
Thu Nov 20 10:04:14 2014 : Protocol-Reject for unsupported protocol 0x22ff
Thu Nov 20 10:04:15 2014 : received CCP RESETREQ
Thu Nov 20 10:04:16 2014 : Protocol-Reject for unsupported protocol 0xb9
Thu Nov 20 10:04:18 2014 : Protocol-Reject for unsupported protocol 0x8e63
Thu Nov 20 10:04:23 2014 : Protocol-Reject for unsupported protocol 0x2c26
Thu Nov 20 10:04:56 2014 : Protocol-Reject for unsupported protocol 0x3e5f
(repeated)
Thu Nov 20 10:08:01 2014 : Protocol-Reject for unsupported protocol 0x1200
Thu Nov 20 10:08:02 2014 : Protocol-Reject for unsupported protocol 0x5601
Thu Nov 20 10:08:04 2014 : Protocol-Reject for unsupported protocol 0x55
Thu Nov 20 10:08:08 2014 : Protocol-Reject for unsupported protocol 0x31
Thu Nov 20 10:08:14 2014 : [DISCONNECT]
Thu Nov 20 10:08:14 2014 : Hangup (SIGHUP)
Thu Nov 20 10:08:14 2014 : MPPE disabled
Thu Nov 20 10:08:14 2014 : Connection terminated.
Thu Nov 20 10:08:14 2014 : Connect time 22.3 minutes.
Thu Nov 20 10:08:14 2014 : Sent 2021179 bytes, received 153081277 bytes.
Thu Nov 20 10:08:14 2014 : PPTP disconnecting...
Thu Nov 20 10:08:14 2014 : PPTP clearing port-mapping for en0
Thu Nov 20 10:08:14 2014 : PPTP disconnected




#2

Hi,

May I know what is your firmware version?


#3

6.1.2 build 1597


#4

After some research I started to suspect problem with packet size errors, but the router auto-negotiated MTU size of 1500, larger than the previous default setting of 1440.
Are there any specific MTU values I should try if I decrease the size? From what I read, MTU 1500 is fairly conservative, and network speed at both ends is decent.

I also learned that with higher speed, it takes more time before connection eventually breaks (5-8 min. before critical timeout error over 15Mbps, more than 20 min. over 50Mbps).
I don’t know much about networks, that’s why I started with this forum.


#5

It does sound like an MTU issue. You can try 1400 (then 1300) and see if it’s any better. Please let us know your findings. Thanks.


#6

We tried different values between 1300 and 1500 and large file transfer still fails with the same protocol reject errors.
We tried PPTP client over different ISP and the transfer was successful.
Chances are, the ISP is not telling us everything or it could be the home router config.
The connection reportedly worked great during first week or so, in the exact same setting.


#7

Thank you for your sharing.