ritul wrote: > > Hi all > > I am having one doubt regarding software compression. I had > read on internet > that HDLC wont support compression.
Cisco supports software compression for HDLC using the Stacker (LZS) algorithm. Cisco doesn't support hardware compression for HDLC. See this link: http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/12cgcr/dial_c/dcsyncs.htm#3846 Whatever you read on the Internet may not apply to Cisco, whose HDLC implementation is simplified compared to older implementations and implementations from other vendors. Cisco HDLC is connectionless with no error recovery for one thing. Software compression for an HDLC link can cause performance problems. Don't use it if the router CPU load exceeds 65%. > Is it correct. > If you can, Is there any performance issues beteen PPP > encapsulation and HDLC > encapsulation. Can any guide me. Urgent Response please. Encapsulation? Is this a different topic, or are you asking us to compare compression performance for HDLC versus PPP? Cisco IOS software supports the following data compression methods for PPP: Stacker compression Predictor compression Microsoft Point-to-Point Compression (MPPC) According to the following link, for some routers, you can do PPP Stacker compression in hardware, which you can't do for HDLC. But the link also implies that as long as the CPU isn't overloaded and there's enough memory for compression dictionaries, software compression doesn't perform more poorly than hardware compression anyway. http://www.cisco.com/warp/public/116/wan_compression_faq.html If the question is simply asking us to compare performance of HDLC versus PPP encapsulation, the answer is there's no differnce. Cisco HDLC looks exactly like PPP encapsulation. Of course, PPP has many other features that HDLC doesn't have and does a formal connection setup with LCP and NCP, negotiates paramaters with LCP, and supports PAP and CHAP, whereas HDLC does not. So the setup could take a few extra milliseconds compared to HDLC, but once traffic flows, there's no difference in efficiency or performance with PPP encapsulation versus Cisco HDLC encapsulation. Hope that helps? Priscilla Oppenheimer http://www.troubleshootingnetworks.com/ > > > Thanks/Regards, > Ritu Lokwani > > Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=66408&t=66319 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
