logging in or signing up tsv area 3 Mentor Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 224 Category: Product Traini.. License: All Rights Reserved Like it (0) Dislike it (0) Added: June 19, 2007 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... Premium member Presentation Transcript Implementation Report on Experiences with Various TCP RFCs: Implementation Report on Experiences with Various TCP RFCs Murari Sridharan muraris@microsoft.com Deepak Bansal dbansal@microsoft.com Dave Thaler dthaler@microsoft.com We did a new implementation of a bunch of RFCs…: We did a new implementation of a bunch of RFCs… Started new TCP/IP stack in 2001, shipped in Windows Vista. Including: Window Scaling (RFC 1323, PS) ECN (RFC 3168, PS) DSACK (RFC 3708, EXPERIMENTAL) F-RTO (RFC 4138, EXPERIMENTAL) Then we did lots of testing of the RFCs above… Window Scaling (RFC 1323), 1/3: Window Scaling (RFC 1323), 1/3 Previously in Windows, but off by default We ran into a number of problems testing it for Vista: IGD problems: multiple popular vendors, popular models Popular vendor #1, several models having SPI block TCP handshake with WS: automatic detection and recovery at end system Popular vendor #2, models with SPI drop packets on connections after a large scaling factor (andgt;2) successfully negotiated during initial handshake: no way to recover at TCP layer Firewall problems: multiple vendors have almost identical bug in old versions Multiple popular vendors, multiple old models (one only if a non-default feature enabled) drop packets if scaling factor andgt; 2 has been negotiated Core Issue: Broken firewall logic that does not scale window in TCP headers correctly while determining how much data to let through Window Scaling, 2/3: Window Scaling, 2/3 More problems… Broken websites: websites running old versions of firewalls in front of their web servers are broken when scaling factor andgt; 2 is negotiated A more thorough testing (of over 10 million websites) has revealed 2-4% websites impacted by this issue Proxy problems: Popular web proxy TCP splicing option (has been disabled by default since 2006) has problems understanding the scale factor. Window Scaling, 3/3: Window Scaling, 3/3 Bottom Line: Problems are fairly likely if used by a consumer (not behind a proxy) Much less problematic if behind a proxy since proxy may not negotiate Window Scaling Result: Limited to scale factor of 2 in Windows Vista for HTTP connections ECN (RFC 3168), 1/2: ECN (RFC 3168), 1/2 New for Windows Vista Straightforward to implement We ran into a number of problems: IGD problem #1: one of the most popular versions from one of the most popular vendors When a data packet arrives with either ECT(0) or ECT(1) (indicating successful ECN capability negotiation) indicated, router crashed Cannot be recovered at TCP layer IGD problem #2: multiple popular vendors with popular models When the 3-way handshake completes, prior to any data being sent, router hit a bug causing further packet loss Easily detected and recovered at TCP layer ECN, 2/2: ECN, 2/2 Bottom Line: Problems are fairly likely if used by a consumer (bad IGDs exist) Much less problematic in campuses and enterprises (IGDs less likely to be present) Result: Turned off by default in Windows Vista DSACK (RFC 3708): DSACK (RFC 3708) New for Windows Vista Straightforward to implement No issues yet Now enabled by default Actual benefits hard to quantify to a specific improvement in real world F-RTO (RFC 4138): F-RTO (RFC 4138) New for Windows Vista Straightforward to implement No issues yet Now enabled by default We have seen improvements in wireless environments but we have not isolated the benefits to specific enhancements We agree with advancing F-RTO to PS Questions?: Questions? Details will be at http://support.microsoft.com/kb/934430 (not published yet) You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.
tsv area 3 Mentor Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 224 Category: Product Traini.. License: All Rights Reserved Like it (0) Dislike it (0) Added: June 19, 2007 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... Premium member Presentation Transcript Implementation Report on Experiences with Various TCP RFCs: Implementation Report on Experiences with Various TCP RFCs Murari Sridharan muraris@microsoft.com Deepak Bansal dbansal@microsoft.com Dave Thaler dthaler@microsoft.com We did a new implementation of a bunch of RFCs…: We did a new implementation of a bunch of RFCs… Started new TCP/IP stack in 2001, shipped in Windows Vista. Including: Window Scaling (RFC 1323, PS) ECN (RFC 3168, PS) DSACK (RFC 3708, EXPERIMENTAL) F-RTO (RFC 4138, EXPERIMENTAL) Then we did lots of testing of the RFCs above… Window Scaling (RFC 1323), 1/3: Window Scaling (RFC 1323), 1/3 Previously in Windows, but off by default We ran into a number of problems testing it for Vista: IGD problems: multiple popular vendors, popular models Popular vendor #1, several models having SPI block TCP handshake with WS: automatic detection and recovery at end system Popular vendor #2, models with SPI drop packets on connections after a large scaling factor (andgt;2) successfully negotiated during initial handshake: no way to recover at TCP layer Firewall problems: multiple vendors have almost identical bug in old versions Multiple popular vendors, multiple old models (one only if a non-default feature enabled) drop packets if scaling factor andgt; 2 has been negotiated Core Issue: Broken firewall logic that does not scale window in TCP headers correctly while determining how much data to let through Window Scaling, 2/3: Window Scaling, 2/3 More problems… Broken websites: websites running old versions of firewalls in front of their web servers are broken when scaling factor andgt; 2 is negotiated A more thorough testing (of over 10 million websites) has revealed 2-4% websites impacted by this issue Proxy problems: Popular web proxy TCP splicing option (has been disabled by default since 2006) has problems understanding the scale factor. Window Scaling, 3/3: Window Scaling, 3/3 Bottom Line: Problems are fairly likely if used by a consumer (not behind a proxy) Much less problematic if behind a proxy since proxy may not negotiate Window Scaling Result: Limited to scale factor of 2 in Windows Vista for HTTP connections ECN (RFC 3168), 1/2: ECN (RFC 3168), 1/2 New for Windows Vista Straightforward to implement We ran into a number of problems: IGD problem #1: one of the most popular versions from one of the most popular vendors When a data packet arrives with either ECT(0) or ECT(1) (indicating successful ECN capability negotiation) indicated, router crashed Cannot be recovered at TCP layer IGD problem #2: multiple popular vendors with popular models When the 3-way handshake completes, prior to any data being sent, router hit a bug causing further packet loss Easily detected and recovered at TCP layer ECN, 2/2: ECN, 2/2 Bottom Line: Problems are fairly likely if used by a consumer (bad IGDs exist) Much less problematic in campuses and enterprises (IGDs less likely to be present) Result: Turned off by default in Windows Vista DSACK (RFC 3708): DSACK (RFC 3708) New for Windows Vista Straightforward to implement No issues yet Now enabled by default Actual benefits hard to quantify to a specific improvement in real world F-RTO (RFC 4138): F-RTO (RFC 4138) New for Windows Vista Straightforward to implement No issues yet Now enabled by default We have seen improvements in wireless environments but we have not isolated the benefits to specific enhancements We agree with advancing F-RTO to PS Questions?: Questions? Details will be at http://support.microsoft.com/kb/934430 (not published yet)