VPN - Error 721

  • Thread starter Thread starter Diana Kaiser
  • Start date Start date
D

Diana Kaiser

I am trying to connect to my work throught VPN. I keep
getting this error code. I checked with administrator and
everyone else is logging in okay. Administrator says that
perhaps i need to uninstall vpn and reinstall. How do you
do that? I am using windows 2000 profressional and have
cable modem with Comcast.
Help
 
Hi Diana,

The 721 error usually indicates the GRE (IP Protocol 47) is being blocked.
Since clients from other locations can access the VPN server itis likely
that either you have a router blocking GRE or you need to contact Comcast
to make sure they are allowing GRE traffic.

Thanks,
Marc Reynolds
Microsoft Technical Support
 
This is a followup to my last message. It turns out that today's
outage was not Comcast's fault. There was a failure on the office
RRAS end that went undetected ( it's a system tucked away were no one
looks at it as a rule). So, to repeat, Comcast did fix the problem
and GRE packets are now getting through fine as of yesterday.

For those of you debugging this sort of thing, you might want to go to
http://www.sbsfaq.com/Files/ to download the file pptpping.zip which
has software that you run on both ends of the RRAS tunnel to determine
what is or is not working to establish a connection. It looks like a
promising tool from the documentation although I've not yet used it
myself.

I was able to operate both ends of my RRAS tunnel from either end
because I'd previously put up Linux servers with SSH tunnels at both
locations. That would allow me to enter the other site with a telnet
style interface. It would also allow me to pass ports on remote
systems to the local system. So I also run VNC servers on both RRAS
systems (I utilize the filters on RRAS to preclude entry by hackers
from the outside end). By passing the VNC port of the remote system
through SSH to my local system, I can effectively operate that remote
system. If I had needed it, I could have used this alternate tunnel
to set up the pptpping software on both ends.

Good luck all!!
 
I live in Plano, TX (Dallas) and have not been able to VPN since
Tuesday. I still can't as of about 15 minutes ago. I thought an MS
patch had hosed me, so I've reinstalled XP THREE times this week.
That's not so bad though, I was due for one anyways. And with a P4
2.8, 1G RAM, and Raid-0, it only takes about 30 minutes start to
finish... :-)
 
Hello Doug,

I have Comcast broadband. I too was having problems with VPN for the past
two days. I failed with error 721. As simple as it may seem, once I
rebooted my cable modem I could then create a VPN session. It might be
worth a try.


Shane Brasher
MCSE (2000,NT),MCSA, A+
Microsoft Platforms Support
Windows NT/2000 Networking
 
Where are you located? We're having the same problem (starting at the
same time) with some of our employees located in Bellevue and Renton,
WA who connect via Comcast. Interestingly enough, another employee in
Seattle who uses Comcast is able to connect just fine.

We've found dealing with Comcast just as frustrating as you report--if
anyone knows a way to report problems to someone who will actually
understand them, let alone do something about it, please let me know!
Maybe we could band together and file a complaint with the cable
francise boards, or talk to a newspaper.
Click to expand...

We had the same problem in the Seattle area. After HOURS upon HOURS
of battling with Comcast, I managed to get through to someone who told
me that they'd made changes to the cable modem config/firmware files
to address the MSBlaster worm. Anyone with a cable modem on the old
configuration would now be unable to pass certain types of packets
such as GRE and ICMP. Power cycling the modem will cause it to
download the new configuration from Comcast's TFTP server as part of
the synch process. For me it only worked after I turned the modem
off, disconnected the cable cord for a while, turned the modem back
on, and then reconnected the cable cord.
 
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