I am posting this because I have been working on this for a month or so to track down the nature of this issue in hopes that anyone who faces this issue can solve it faster than I did. Some of you may already know this but… for those who don’t this may prove useful information.
Issue:
We have a 768 DSL PPPOE connection to the Internet for our business. Recently I have installed an Exchange 2000 Server with "Outlook Web Access" (provides users with web access to their mailboxes from any web browser). Initially I thought I must have installed the Server wrong since users couldn't connect to their mailboxes but... I tracked it down to Winroute not letting users through because of IPFrag Mode being disabled. Once I enabled IPFrag mode on the system designated as the Gateway to the net, the users could connect to their mailboxes via the web browser with no further issues. Well... all sounds well and good at this point but... some users that surf the web daily noticed since enabling IPFrag mode sending email to yahoo mail accounts has become a hit or miss. Mail will sporadically make it through the firewall if at all. Some people also cannot access their hotmail accounts. Example... On Hotmail, a user name of "willwest1234" can access his mail account but...may not be able to send a composed email. On the other hand a user name with an "Underscore" in it like "joe_blow" will not be able to log in to his mail account at all. If I turn IPFrag mode off these users can access their Hotmail accounts, and send to Yahoo mail accounts with zero issues, but then the users are not able to access their company mailboxes via "Outlook Web Access" again. If I turn IPFrag mode back on I fix one problem but create another, and vice versa.
Solution:
I have tracked it down to the PPPoE DSL Internet connection and the PC/Exchange Server TCP/IP configuration. I had to modify the client PC’s and Exchange Server by lowering their MTU setting to 1472(if I remember right). I used a utility called “TCP/IP Optimizer” that I picked up somewhere which worked flawlessly. In the end I now have IPFrag Mode enabled on the Gateway PC, which allows the people to access Outlook Web Access. The users also can send to yahoo mail accounts, and login to Hotmail with no further issues.
Mike Ita
Issue:
We have a 768 DSL PPPOE connection to the Internet for our business. Recently I have installed an Exchange 2000 Server with "Outlook Web Access" (provides users with web access to their mailboxes from any web browser). Initially I thought I must have installed the Server wrong since users couldn't connect to their mailboxes but... I tracked it down to Winroute not letting users through because of IPFrag Mode being disabled. Once I enabled IPFrag mode on the system designated as the Gateway to the net, the users could connect to their mailboxes via the web browser with no further issues. Well... all sounds well and good at this point but... some users that surf the web daily noticed since enabling IPFrag mode sending email to yahoo mail accounts has become a hit or miss. Mail will sporadically make it through the firewall if at all. Some people also cannot access their hotmail accounts. Example... On Hotmail, a user name of "willwest1234" can access his mail account but...may not be able to send a composed email. On the other hand a user name with an "Underscore" in it like "joe_blow" will not be able to log in to his mail account at all. If I turn IPFrag mode off these users can access their Hotmail accounts, and send to Yahoo mail accounts with zero issues, but then the users are not able to access their company mailboxes via "Outlook Web Access" again. If I turn IPFrag mode back on I fix one problem but create another, and vice versa.
Solution:
I have tracked it down to the PPPoE DSL Internet connection and the PC/Exchange Server TCP/IP configuration. I had to modify the client PC’s and Exchange Server by lowering their MTU setting to 1472(if I remember right). I used a utility called “TCP/IP Optimizer” that I picked up somewhere which worked flawlessly. In the end I now have IPFrag Mode enabled on the Gateway PC, which allows the people to access Outlook Web Access. The users also can send to yahoo mail accounts, and login to Hotmail with no further issues.
Mike Ita
