{"id":180,"date":"2008-12-17T23:56:51","date_gmt":"2008-12-17T22:56:51","guid":{"rendered":"http:\/\/www.tsls.co.uk\/?p=180"},"modified":"2026-03-11T10:42:35","modified_gmt":"2026-03-11T10:42:35","slug":"network-communications-issue-with-win2k3-sp1","status":"publish","type":"post","link":"https:\/\/www.tsls.co.uk\/index.php\/2008\/12\/17\/network-communications-issue-with-win2k3-sp1\/","title":{"rendered":"Network Communications issue with Win2k3 SP2"},"content":{"rendered":"<p>For the last couple of days I have been battling with a network mystery where by user traffic to MS TFS (Team Foundation Server) over the ISA 2006 VPN SITE-TO-SITE was denying access to TFS. Users on the internal network or using the VPN client were unaffected. Nothing had changed on the servers or clients.<\/p>\n<p>The Network Topology<\/p>\n<p>TFS Client -&gt; Site2 ISA 2006 SP1 -. IPSEC SITE-TO-SITE \u2013Site1\u00a0 ISA 2006\u00a0 -&gt; TFS Server<\/p>\n<p>The error being raised in VS.Net was Team Explorer could not connect to the Team Foundation Server xxxxxx<\/p>\n<p>No error on Site 1 ISA<\/p>\n<p>Error on Site 2 ISA was FWX_E_TCP_NOT_SYN_PACKET_DROPPED to the TFS Server<\/p>\n<p>Network monitors would show a request to the TFS Server but no responses, the TFS Client would show several retransmissions<\/p>\n<p>After a lot of work we discovered that the TFS Server was running windows 2003 SP2, when SP2 is installed it will enable TCP\/IP Offload (RSS) for improved network performance, however this improvement can cause it own problems.\u00a0<\/p>\n<p>After running through <a href=\"http:\/\/support.microsoft.com\/kb\/948496\/\">http:\/\/support.microsoft.com\/kb\/948496\/<\/a> to disable the TCP\/IP Offload, then rebooting the server the traffic to TFS then started to work.<\/p>\n<p>TCP\/IP offload has also been removed from the ISA Servers.<\/p>\n<p>If you experience networking connectivity issues to windows servers then disabling TCP\/IP is a good place to start.<\/p>\n<p>Thanks to Andreas on the Microsoft ISA Server Premier Support Team, without him we would have never tried KB948496.<br \/>\nThe following issues may occur when Windows Server 2003 SNP is turned on:<\/p>\n<ul>\n<li>When you try to connect to the server by using a VPN connection, you receive the following error message:\n<div class=\"kb_errormsgbody\">\n<div class=\"kb_errorcontent\">\n<div class=\"errormsg\">Error 800: Unable to establish connection.<\/div>\n<\/div>\n<\/div>\n<\/li>\n<li>You cannot create a Remote Desktop Protocol (RDP) connection to the server.<\/li>\n<li>You cannot connect to shares on the server from a computer on the local area network.<\/li>\n<li>You cannot join a client computer to the domain.<\/li>\n<li>You cannot connect to the Exchange server from a computer that is running Microsoft Outlook.<\/li>\n<li>Inactive Outlook connections to the Exchange server may not be cleaned up.<\/li>\n<li>You experience slow network performance.<\/li>\n<li>You may experience slow network performance when you communicate with a Windows Vista-based computer.<\/li>\n<li>You cannot create an outgoing FTP connection from the server.<\/li>\n<li>The Dynamic Host Configuration Protocol (DHCP) server service crashes.<\/li>\n<li>You experience slow performance when you log on to the domain.<\/li>\n<li>Network Address Translation (NAT) clients that are located behind Windows Small Business Server 2003 or Internet Security and Acceleration (ISA) Server experience intermittent connection failures.<\/li>\n<li>You experience intermittent RPC communications failures.<\/li>\n<li>The server stops responding.<\/li>\n<li>The server runs low on nonpaged pool memory<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>For the last couple of days I have been battling with a network mystery where by user traffic to MS TFS (Team Foundation Server) over the ISA 2006 VPN SITE-TO-SITE was denying access to TFS.<\/p>\n","protected":false},"author":11,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_newsletter_tier_id":0,"footnotes":"","jetpack_publicize_message":"","jetpack_is_tweetstorm":false,"jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false}}},"categories":[21],"tags":[],"class_list":["post-180","post","type-post","status-publish","format-standard","hentry","category-microsoft"],"jetpack_publicize_connections":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v21.9.1 - 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