Thanks for your answer, and yup I’ve read the Cisco document before but I was unsure about it’s validity in real life.

Thanks for you nice words, I just want to say that we are not yet experts we are just trying to be

For PPP we can use /31 addresses and even unnumbered interfaces for better conservation of the address pool. check out this post for more information http://networkers-online.com/blog/?p=23

Check this document for more information about using /31 address for PPP connections http://www.cisco.com/en/US/docs/ios/12_2t/12_2t2/feature/guide/ft31addr.html

For the second question as I know PPP is providing error detection only and not error correction. The correction function is left to the upper layer protocols. PPP will only drop the corrupted frames and will not try to make any corrections.

I hope this answered your questions…

I’m very pleased to find this resource of network information maintained by three of experts for free! God give you strength and patience to be able to keep it running.

I have two questions regarding the PPP on serial links.

1- Why don’t we use a /31 prefix masks? I did a little search and I found it can be used (although there no host addresses)! So is it possible? and why wouldn’t we use it to conserve our address pool?

2- For PPP, Does it support an Error Correction? or Error Detection only and the correction are kept to the higher layer TCP to be handled?

Actually, Some books says that it’s an error correction protocol but not by default, and others state that PPP never handles error correction!

Thanks in advance.

Note: I’ll write down the questions that I failed to find answers for under every category if it won’t bother you.