Re: Difference between Urgent and Push bit

What is CR in telnet
can u explain me it clearly

On Mon, Jan 31, 2011 at 4:47 PM, Carlos G Mendioroz <tron_at_huapi.ba.ar>wrote:

> AFAIK, URGENT implements a kind of OOB (Out Of Band) channel inside
> the TCP connection. Urgent data can "jump over" the queued stream
> data to bring an urgent message to the other side.
>
> PUSH, on the other way, kind of "flushes" the queue, making sure
> a transmission is done with whatever data is there (queued before
> or in the current packet). This is helpful e.g. to send binary
> messages on TCP protocols that might get delayed because of a
> commonly implemented option that delays packets when there is no
> CR at the end, or are too short, to make telnet sessions more efficient.
>
> I remember a TCP mod to this end, but I can not recall its name now.
>
> -Carlos
>
> Scott M Vermillion @ 31/01/2011 00:25 -0300 dixit:
>
> >However the urgent flag is probably used when you want to convey this
>> message to the application.
>>
>> "TCP/IP Illustrated, Volume 1" (Stevens) offers examples of Urgent mode
>> in Chapters 26 & 27 (and it's discussed in general terms in Chapter 20).
>> Fair warning: this is an obviously somewhat dated text (copyright 1994)
>> and the examples are very, very dry. Here's a quote from Ch 20:
>>
>> "What is urgent mode used for? The two most commonly used applications
>> are Telnet and Rlogin, when the interactive user types the interrupt key,
>> and we show examples of this use of urgent mode in Chapter 26. Another is
>> FTP, when the interactive user aborts a file transfer, and we show an
>> example of this in Chapter 27."
>>
>> And an interesting quote from the same chapter relative to the Push flag:
>>
>> "Berkley-derived implementations ignore a received PUSH flag because they
>> normally never delay the delivery of received data to the application."
>>
>> ____________________________________________
>> There are only 10 types of people in the world:
>> Those who understand binary and those who do not...
>>
>> On Jan 30, 2011, at 7:52 , VIJAY SHEKHAR wrote:
>>
>> Well Push flag is used to let receiving OSI stack know that the data can
>>> now be pushed to the application it need not wait for more segments.
>>> However the urgent flag is probably used when you want to convey this
>>> message to the application. The application should support this if I am not
>>> mistaken.
>>>
>>> -Vijay Shekhar
>>> CCIE#17589/CISSP#65114/RHCE
>>> http://au.linkedin.com/in/vshekhar
>>>
>>>
>>> Quoting HEMANTH RAJ <hemanthrj_at_gmail.com>:
>>>
>>> What is the difference between urgent and Push bit in TCP Header
>>>>
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>>>> Cisco Systems Inc.
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>>
>>
>>
>>
>>
>>
> --
> Carlos G Mendioroz <tron_at_huapi.ba.ar> LW7 EQI Argentina
>

-- 
Problems arise because we talk,problems are not solved because we don't talk
So good or bad talk to your affectionate one's freely.
Yours Friendly,
HP HEMANTH RAJ
Cisco Systems Inc.
Blogs and organic groups at http://www.ccie.net