linuxptp-users

[Linuxptp-users] Port option: logMinDelayReqInterval

[Chandra M. <sma...@al...>]

Hi Friends,

I have had some difficulty in using the following option.


1.      I have used it as follows only at slave as keeping this option at the master does not make sense (the slave initiates these packets). In fact, I have varied the number between -1 to -5 to check the effect of increased frequency of pathdelay calculations (2 DelayReq packets per second to 32 DelayReq packets per second). Please note that I have used the negative numbers to suit the frequency to the mean interval between packets. Is the following usage correct?

[global]
logMinDelayReqInterval -5


2.      However, irrespective of the of the option number between -1 and -5, I have always got the following message.

Ptp4l[3022.814]: port 1: minimum delay request interval 2^0



What does this mean? If the message is correct, the numbers that have been used in the above option have not been used by the ptp4l and they have been defaulted to 0. If that is the case, how can I use the option correctly? Should I use the above option with any other options to cause its effect on the ptp operation?




Please clarify.

Thanking you in anticipation,
Regards,
Chandra

(c) : 0175508142
(O): 701.6412

"Knowledge speaks, Wisdom listens"


________________________________

Confidentiality Notice.
This message may contain information that is confidential or otherwise protected from disclosure. If you are not the intended recipient, you are hereby notified that any use, disclosure, dissemination, distribution, or copying of this message, or any attachments, is strictly prohibited. If you have received this message in error, please advise the sender by reply e-mail, and delete the message and any attachments. Thank you.

Re: [Linuxptp-users] Port option: logMinDelayReqInterval

[Ledda W. E. <Wil...@it...>]

I didn't check the code, but I suppose that ptp4l expects to work with positive numbers. It is possible that if forces the value to zero otherwise.


From: Chandra Mallela [mailto:sma...@al...]
Sent: 16 March 2015 11:22
To: lin...@li...
Subject: [Linuxptp-users] Port option: logMinDelayReqInterval



Hi Friends,

I have had some difficulty in using the following option.


1.      I have used it as follows only at slave as keeping this option at the master does not make sense (the slave initiates these packets). In fact, I have varied the number between -1 to -5 to check the effect of increased frequency of pathdelay calculations (2 DelayReq packets per second to 32 DelayReq packets per second). Please note that I have used the negative numbers to suit the frequency to the mean interval between packets. Is the following usage correct?

[global]
logMinDelayReqInterval -5


2.      However, irrespective of the of the option number between -1 and -5, I have always got the following message.

Ptp4l[3022.814]: port 1: minimum delay request interval 2^0



What does this mean? If the message is correct, the numbers that have been used in the above option have not been used by the ptp4l and they have been defaulted to 0. If that is the case, how can I use the option correctly? Should I use the above option with any other options to cause its effect on the ptp operation?




Please clarify.

Thanking you in anticipation,
Regards,
Chandra

(c) : 0175508142
(O): 701.6412

"Knowledge speaks, Wisdom listens"


________________________________

Confidentiality Notice.
This message may contain information that is confidential or otherwise protected from disclosure. If you are not the intended recipient, you are hereby notified that any use, disclosure, dissemination, distribution, or copying of this message, or any attachments, is strictly prohibited. If you have received this message in error, please advise the sender by reply e-mail, and delete the message and any attachments. Thank you.

Re: [Linuxptp-users] Port option: logMinDelayReqInterval

[Chandra M. <sma...@al...>]

Hi William,

Thank you for your response.

Please note that the intended frequencies of Delay Request packets usually run till about 512 packets per second. Thus, the minimum interval time is 1/512 seconds between packets. It means that 2^(-9). Thus, negative numbers make sense more than positive numbers. Thus, we should be able to set these negative numbers.

As I am end user, I have not looked at the code. I appreciate further inputs on this.

BTW I have already used -ve numbers for logSyncInterval up to -9. Things seem to be fine out there.

Thanking you in anticipation,
Regards,
Chandra

(c) : 0175508142
(O): 701.6412

"Knowledge speaks, Wisdom listens"

From: Ledda William EXT [mailto:Wil...@it...]
Sent: Monday, March 16, 2015 6:38 PM
To: Chandra Mallela; lin...@li...
Subject: RE: Port option: logMinDelayReqInterval

I didn't check the code, but I suppose that ptp4l expects to work with positive numbers. It is possible that if forces the value to zero otherwise.


From: Chandra Mallela [mailto:sma...@al...]
Sent: 16 March 2015 11:22
To: lin...@li...<mailto:lin...@li...>
Subject: [Linuxptp-users] Port option: logMinDelayReqInterval



Hi Friends,

I have had some difficulty in using the following option.


1.      I have used it as follows only at slave as keeping this option at the master does not make sense (the slave initiates these packets). In fact, I have varied the number between -1 to -5 to check the effect of increased frequency of pathdelay calculations (2 DelayReq packets per second to 32 DelayReq packets per second). Please note that I have used the negative numbers to suit the frequency to the mean interval between packets. Is the following usage correct?

[global]
logMinDelayReqInterval -5


2.      However, irrespective of the of the option number between -1 and -5, I have always got the following message.

Ptp4l[3022.814]: port 1: minimum delay request interval 2^0



What does this mean? If the message is correct, the numbers that have been used in the above option have not been used by the ptp4l and they have been defaulted to 0. If that is the case, how can I use the option correctly? Should I use the above option with any other options to cause its effect on the ptp operation?




Please clarify.

Thanking you in anticipation,
Regards,
Chandra

(c) : 0175508142
(O): 701.6412

"Knowledge speaks, Wisdom listens"


________________________________

Confidentiality Notice.
This message may contain information that is confidential or otherwise protected from disclosure. If you are not the intended recipient, you are hereby notified that any use, disclosure, dissemination, distribution, or copying of this message, or any attachments, is strictly prohibited. If you have received this message in error, please advise the sender by reply e-mail, and delete the message and any attachments. Thank you.

________________________________

Confidentiality Notice.
This message may contain information that is confidential or otherwise protected from disclosure. If you are not the intended recipient, you are hereby notified that any use, disclosure, dissemination, distribution, or copying of this message, or any attachments, is strictly prohibited. If you have received this message in error, please advise the sender by reply e-mail, and delete the message and any attachments. Thank you.

Re: [Linuxptp-users] Port option: logMinDelayReqInterval

[Chandra M. <sma...@al...>]

Hi William et al,

I think I have resolved the issue though not sure whether it is the right way. When I have used the option 'logMinDelayReqInterval -5' in ptp4l.conf at both slave and master (as opposed to just at the slave), I could see that the frequency of delay calculations has increased. Perhaps, at the slave, the option might imply 'number of delay request packets to be sent' and at the master, 'number of delay request packets to be processed'. Only when they match, the ptp4l is taking the option into consideration.

Please feel free to pass your comments.

Thanking you in anticipation,
Regards,
Chandra

(c) : 0175508142
(O): 701.6412

"Knowledge speaks, Wisdom listens"

From: Chandra Mallela
Sent: Monday, March 16, 2015 6:55 PM
To: 'Ledda William EXT'; lin...@li...
Subject: RE: Port option: logMinDelayReqInterval



Hi William,

Thank you for your response.

Please note that the intended frequencies of Delay Request packets usually run till about 512 packets per second. Thus, the minimum interval time is 1/512 seconds between packets. It means that 2^(-9). Thus, negative numbers make sense more than positive numbers. Thus, we should be able to set these negative numbers.

As I am end user, I have not looked at the code. I appreciate further inputs on this.

BTW I have already used -ve numbers for logSyncInterval up to -9. Things seem to be fine out there.

Thanking you in anticipation,
Regards,
Chandra

(c) : 0175508142
(O): 701.6412

"Knowledge speaks, Wisdom listens"

From: Ledda William EXT [mailto:Wil...@it...]
Sent: Monday, March 16, 2015 6:38 PM
To: Chandra Mallela; lin...@li...<mailto:lin...@li...>
Subject: RE: Port option: logMinDelayReqInterval

I didn't check the code, but I suppose that ptp4l expects to work with positive numbers. It is possible that if forces the value to zero otherwise.


From: Chandra Mallela [mailto:sma...@al...]
Sent: 16 March 2015 11:22
To: lin...@li...<mailto:lin...@li...>
Subject: [Linuxptp-users] Port option: logMinDelayReqInterval



Hi Friends,

I have had some difficulty in using the following option.


1.      I have used it as follows only at slave as keeping this option at the master does not make sense (the slave initiates these packets). In fact, I have varied the number between -1 to -5 to check the effect of increased frequency of pathdelay calculations (2 DelayReq packets per second to 32 DelayReq packets per second). Please note that I have used the negative numbers to suit the frequency to the mean interval between packets. Is the following usage correct?

[global]
logMinDelayReqInterval -5


2.      However, irrespective of the of the option number between -1 and -5, I have always got the following message.

Ptp4l[3022.814]: port 1: minimum delay request interval 2^0



What does this mean? If the message is correct, the numbers that have been used in the above option have not been used by the ptp4l and they have been defaulted to 0. If that is the case, how can I use the option correctly? Should I use the above option with any other options to cause its effect on the ptp operation?




Please clarify.

Thanking you in anticipation,
Regards,
Chandra

(c) : 0175508142
(O): 701.6412

"Knowledge speaks, Wisdom listens"


________________________________

Confidentiality Notice.
This message may contain information that is confidential or otherwise protected from disclosure. If you are not the intended recipient, you are hereby notified that any use, disclosure, dissemination, distribution, or copying of this message, or any attachments, is strictly prohibited. If you have received this message in error, please advise the sender by reply e-mail, and delete the message and any attachments. Thank you.

________________________________

Confidentiality Notice.
This message may contain information that is confidential or otherwise protected from disclosure. If you are not the intended recipient, you are hereby notified that any use, disclosure, dissemination, distribution, or copying of this message, or any attachments, is strictly prohibited. If you have received this message in error, please advise the sender by reply e-mail, and delete the message and any attachments. Thank you.

Re: [Linuxptp-users] Port option: logMinDelayReqInterval

[Miroslav L. <mli...@re...>]

On Tue, Mar 17, 2015 at 11:18:20AM +0000, Chandra Mallela wrote:
> I think I have resolved the issue though not sure whether it is the right way. When I have used the option 'logMinDelayReqInterval -5' in ptp4l.conf at both slave and master (as opposed to just at the slave), I could see that the frequency of delay calculations has increased. Perhaps, at the slave, the option might imply 'number of delay request packets to be sent' and at the master, 'number of delay request packets to be processed'. Only when they match, the ptp4l is taking the option into consideration.

That option needs to be set on master. On slaves it sets only the
initial value, after receiving first delay response message they will
switch to the value announced by the master.

-- 
Miroslav Lichvar

Re: [Linuxptp-users] Port option: logMinDelayReqInterval

[Ledda W. E. <Wil...@it...>]

Good to know! This is way I get always 2^3 in the slave whatever value I use (it corresponds to the value of the GMC).

Bye

William

-----Original Message-----
From: Miroslav Lichvar [mailto:mli...@re...] 
Sent: 17 March 2015 12:34
To: Chandra Mallela
Cc: Ledda William EXT; lin...@li...
Subject: Re: [Linuxptp-users] Port option: logMinDelayReqInterval

On Tue, Mar 17, 2015 at 11:18:20AM +0000, Chandra Mallela wrote:
> I think I have resolved the issue though not sure whether it is the right way. When I have used the option 'logMinDelayReqInterval -5' in ptp4l.conf at both slave and master (as opposed to just at the slave), I could see that the frequency of delay calculations has increased. Perhaps, at the slave, the option might imply 'number of delay request packets to be sent' and at the master, 'number of delay request packets to be processed'. Only when they match, the ptp4l is taking the option into consideration.

That option needs to be set on master. On slaves it sets only the initial value, after receiving first delay response message they will switch to the value announced by the master.

--
Miroslav Lichvar

Re: [Linuxptp-users] Port option: logMinDelayReqInterval

[Chandra M. <sma...@al...>]

Hi Miroslav,

Please elucidate me on the following.

1.      Which field in the delay response indicates the value to the slave announed by the master? Is it logMessageInterval?
2.      DelayReq packet is sent by the slave. Thus, the number of DelayReq packets to be sent is to be controlled by the slave. Am I right? Why should it be an option with master?

An answer to my own question: It is the master being burdened to respond to possibly many number of slaves. Hence, it controls the number. Is this the rationale for what you have mentioned below?

Thanking you in anticipation,
Regards,
Chandra

(c) : 0175508142
(O): 701.6412

"Knowledge speaks, Wisdom listens"


-----Original Message-----
From: Miroslav Lichvar [mailto:mli...@re...]
Sent: Tuesday, March 17, 2015 7:34 PM
To: Chandra Mallela
Cc: Ledda William EXT; lin...@li...
Subject: Re: [Linuxptp-users] Port option: logMinDelayReqInterval

On Tue, Mar 17, 2015 at 11:18:20AM +0000, Chandra Mallela wrote:
> I think I have resolved the issue though not sure whether it is the right way. When I have used the option 'logMinDelayReqInterval -5' in ptp4l.conf at both slave and master (as opposed to just at the slave), I could see that the frequency of delay calculations has increased. Perhaps, at the slave, the option might imply 'number of delay request packets to be sent' and at the master, 'number of delay request packets to be processed'. Only when they match, the ptp4l is taking the option into consideration.

That option needs to be set on master. On slaves it sets only the initial value, after receiving first delay response message they will switch to the value announced by the master.

--
Miroslav Lichvar



  ________________________________

Confidentiality Notice.
This message may contain information that is confidential or otherwise protected from disclosure. If you are not the intended recipient, you are hereby notified that any use, disclosure, dissemination, distribution, or copying of this message, or any attachments, is strictly prohibited. If you have received this message in error, please advise the sender by reply e-mail, and delete the message and any attachments. Thank you.

Re: [Linuxptp-users] Port option: logMinDelayReqInterval

[Miroslav L. <mli...@re...>]

On Tue, Mar 17, 2015 at 12:47:13PM +0000, Chandra Mallela wrote:
> 1.      Which field in the delay response indicates the value to the slave announed by the master? Is it logMessageInterval?

Yes.

> 2.      DelayReq packet is sent by the slave. Thus, the number of DelayReq packets to be sent is to be controlled by the slave. Am I right? Why should it be an option with master?

Master tells slaves how often they should be polling the master.

> An answer to my own question: It is the master being burdened to respond to possibly many number of slaves. Hence, it controls the number. Is this the rationale for what you have mentioned below?

Yes, I think that's correct. The sync interval is controlled by
master, so the delay interval should be too.

-- 
Miroslav Lichvar

Re: [Linuxptp-users] Port option: logMinDelayReqInterval

[Ledda W. E. <Wil...@it...>]

If you are able to take a look into the IEEE 1588 standards, see section 9.5.11 (Transmission of a Delay_req message) and in particular section 9.5.11.2 (Timing requirements). It states that:

The transmission of the Delay request message from a port SHALL be limited as follows:

- The initial may be transmitted when required
- Following messages in a way such that the mean interval, in seconds, is not less than the value of 2^logMinDelayreqInterval seconds (where logMinDelayreqInterval  us the logMessageInterval field of the last Delay response received)

The standard provides also two option to meet this requirement.

HTH

William
-----Original Message-----
From: Miroslav Lichvar [mailto:mli...@re...] 
Sent: 17 March 2015 14:03
To: Chandra Mallela
Cc: Ledda William EXT; lin...@li...
Subject: Re: [Linuxptp-users] Port option: logMinDelayReqInterval

On Tue, Mar 17, 2015 at 12:47:13PM +0000, Chandra Mallela wrote:
> 1.      Which field in the delay response indicates the value to the slave announed by the master? Is it logMessageInterval?

Yes.

> 2.      DelayReq packet is sent by the slave. Thus, the number of DelayReq packets to be sent is to be controlled by the slave. Am I right? Why should it be an option with master?

Master tells slaves how often they should be polling the master.

> An answer to my own question: It is the master being burdened to respond to possibly many number of slaves. Hence, it controls the number. Is this the rationale for what you have mentioned below?

Yes, I think that's correct. The sync interval is controlled by master, so the delay interval should be too.

--
Miroslav Lichvar