By Doug Arnold. Which delay measurement mechanism is best for deploying IEEE ? Why this is the case should become apparent as we review how these two mechanisms work. With peer-to-peer the slave calculates its clock offset with respect to the master as follows:. No need to combine four timestamps like we did with end-to-end networks. But wait, how did the slave know the network delay?

Instead of sending delay measurement messages from the slave to the master, as with the end-to-end approach, each device on the network exchanges peer-delay measurement messages. That way each device can keep track of the delays between itself and its immediately connected neighbors.

The diagram below shows how this works. Each device periodically initiates an exchange of peer-delay messages on every connected port. Clock A wants to know the delay to Clock B. Clock A also saves the time it sent that message, t1. Clock B saves the time, on its clock, when this message arrives, t2. Clock B will also initiate the same series of messages in the reverse direction so that both clocks know the peer-delay. In the peer-to-peer case we only making that assumption over a cable, not the whole network, and there are no queues.

So unless the cable is very long, that is a good assumption. What about the queues in the switches? At the beginning of this post I said that peer-to-peer only works well when every switch is either a transparent clock or a boundary clock. That way the switch will take care of its own queuing delays. Although the end-to-end mechanism is more versatile, because it can handle ordinary switches and routers, the peer-to-peer mechanism has several advantages in networks where it does work:.

I have a question.In the world of collections, key performance indicators KPIs are incredibly pervasive — and vitally important in measuring recovery on receivables. KPIs are a form of measures used in evaluating how well an organization or employee is meeting certain performance goals. The raw number of available KPIs can get overwhelming. How does one distinguish the most relevant to your bottom line? Although what fits best may vary for different collections departments and organizations, and many collections professionals may have their own favorite KPIs, below are the five that are the most likely indicators of the success and health of your operations.

DSO is the number of days it takes a customer to pay after an invoice has been generated or a sale has been made. One of the most commonly used metrics, DSO is used to calculate how long, on average, it takes to collect from debtors. This makes it easy to compare the performance of your organization against others in the industry to see whether and by how much your performance could stand to improve. It is a measure of the amount collected during a specific period of time against the amount of total receivables during that same period.

CEI should likely be measured by just about any collections organization, as it can track the direction in which your operations are moving over longer periods of time. For collections organizations, the higher this number, the better, since a high score indicates a high success rate of locating debtors.

There are a variety of other KPIs related to calls, such as the number of calls handled and average call time, but perhaps the most relevant to the efficiency and success of your organization is whether these calls are connecting to the correct individual on the other end of the line — which is exactly what the RPC rate measures. Any collections organization with a call center should be using this KPI, and the metric may be improved through using a sophisticated proprietary data and public records solution that leverages real-time data to get the most information possible on the debtor in question.

The PTP rate is as important as your RPC rate in measuring efficiency, and it is the next logical step to a successful collection of debt. With its label being as descriptive as it is, this KPI may not warrant much of an additional explanation: It measures the percentage of all calls made that ended with a promise to pay by the debtor. In short, where the RPC rate measures the success rate of dialing the correct individual, this metric measures the success rate of those RPC calls.

This is another percentage that you want as close to as possible. If your numbers are lower than your peers in the industry, you may have to evaluate the tactics being used by your employees during these calls — not to mention any related employee training programs.

Locating the correct contact is essential to securing a promise to pay. And one of the fastest and easiest methods of finding a correct contact is through a technology solution that offers copious, up-to-date data from sources such as utilities and credit reporting agencies, and one that can dig even deeper by locating known associates of your search target. Finally, PPA measures how much profit is generated on average by each account in collections.

In short, this KPI measures how much each account impacts your bottom line. There are a variety of factors that can work to hinder efforts to maximize profits, essentially all of which can be traceable to one of the inputs in the PPA calculation i.

For example, too sudden of an increase in accounts managed without a corresponding increase in gross profit may lower your PPA. Perhaps further analysis can identify an age beyond which accounts are very unlikely to produce a return of any kind, and thus it would be a waste of resources to attempt to collect on them. Caution may be necessary here, since the constant effort to control costs may limit the tools available to your organization to maximize its effectiveness.

Thus, although costs must indeed be monitored and controlled, the return on investment offered by such tools often outweighs the upfront expense in productivity gains several times over. Organizations will likely want to use even more KPIs than these five, and there is certainly no shortage to choose from. Nevertheless, these specific metrics have been highlighted as those that may be the most telling on the overall health of your operations.

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Details about Arista's use of cookies can be found here. Section 6. The switch uses the system clock for displaying the time and for time-stamping messages. The system clock is set to Coordinated Universal Time UTC ; the switch calculates local time based on the time zone setting. Time-stamps and time displays are in local time. The time zone setting is used by the switch to convert the system time UTC to local time. To specify the time zone, use the clock timezone command. The clock set command manually configures the system clock time and date, in local time.

Any NTP servers properly configured on the switch override time that is manually entered. To display the local time and configured time zone, enter the show clock command.

Network Time Protocol NTP is enabled on the switch by default, and time settings from any properly configured NTP server will override manual setting of the system clock. The switch supports NTP versions 1 through 4. The default is version 4. After configuring the switch to synchronize with an NTP server, it may take up to ten minutes for the switch to set its clock.

End-to-End Versus Peer-to-Peer

The running-config lists NTP servers that the switch is configured to use. The ntp server command adds a server to the list or modifies the parameters of a previously listed address. NTP is enabled by default.

To disable NTP, use the no ntp command.

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The ntp local-interface command configures an interface as the source of NTP packets. For an ntp local-interface command to take effect, the specified interface and the NTP server must both belong to the same VRF. To configure the switch to accept NTP requests on all interfaces, use the ntp serve all command to enable NTP server mode globally on the switch. To configure an individual interface to accept or deny NTP requests, use the ntp serve command.

Interface level settings override the global settings, and changing the settings at either the global or interface level also causes the switch to re-synchronize with its upstream NTP server. NTP server mode is disabled by default.

SPAG: Clocking & Sync Part 2/3: IEEE 1588 and PTPv2

The switch can be configured to synchronize its clock using NTP packets only from an authenticated source. NTP authentication is disabled by default.You can subscribe to this list here. Showing 25 50 results of You seem to have CSS turned off. Please don't fill out this field. Please provide the ad click URL, if possible:. Help Create Join Login. Operations Management.

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Flat Threaded. Oh no! Some styles failed to load. Sign Up No, Thank you. Thanks for helping keep SourceForge clean. X You seem to have CSS turned off. Briefly describe the problem required :. Upload screenshot of ad required :. Mar 2. May Jul Aug GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. If nothing happens, download GitHub Desktop and try again.

If nothing happens, download Xcode and try again. If nothing happens, download the GitHub extension for Visual Studio and try again. The dual design goals are to provide a robust implementation of the standard and to use the most relevant and modern Application Programming Interfaces API offered by the Linux kernel. Supporting legacy APIs and other platforms is not a goal. The source code is managed using the git version control system.

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To get your own copy of the project sources, use the following command. If the git protocol is blocked by your local area network, then you can use the alternative HTTP protocol instead. In order to run this software, you need Linux kernel version 3. Check whether your network interface supports PTP with the following command.

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This command shows whether a MAC supports hardware or software time stamping. The following example output indicates support for hardware time stamping. The next example shows the case where the MAC only supports software time stamping. If this is lacking, then the MAC cannot be used at all. However, adding this capability entails adding a single line of code to the device driver.

If you would like to get involved in improving the software, please join the linuxptp-devel mailing list. Skip to content. Dismiss Join GitHub today GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. Sign up. C Roff Other. Branch: master. Find file. Sign in Sign up. Go back. Launching Xcode If nothing happens, download Xcode and try again. Latest commit. Instead, move on to search for a valid non-faulty state.

If supported, the fault is logged so that management can notice later, but that logging isn't a requirement. Latest commit eee6d0f Oct 24, Supports IEEE Modular design allowing painless addition of new transports and clock servos.

Implements unicast operation.Get the cross timestamping information. The gPTP subsystem uses these samples to calculate ratios which can be used to translate or extrapolate one clock into another clock reference. The gPTP service uses these supplied cross timestamps to perform internal rate estimation and conversion functions. Gets current sync count value.

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It is set to zero when master and incremented at each sync received for slave. Initializes the port. Creates network interface, initializes hardware timestamper and create OS locks conditions.

Restores the serialized state from the buffer. Copies the information from buffer to the variables in that order :. Sets link delay information. Signed value allows this to be negative result because of inaccurate timestamps.

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Adjusts the clock frequency. FALSE otherwise. Adds a foreign master. Adds a new qualified announce the port. IEEE Parameters msg PTP announce message Returns void. Adds New sock addr map. Parameters destIdentity [in] PortIdentity remote remote [in] remote link layer address Returns void.

Switches port to a gPTP master. Returns void. Switches port to a gPTP slave. Gets the "best" announce. Gets the announce interval.

Returns Announce interval. Gets the asCapable flag. Returns asCapable flag. Returns Pointer to clock. FALSE in case of error.

ptp neighbor rate ratio

Gets extended error message from hardware timestamper. Parameters msg [out] Extended error message Returns void. Returns Last pdelay request. Returns Last pdelay response. Returns last pdelay response follow up. Gets last sync message. Gets the link delay information. Increments announce sequence id and returns. Returns Next announce sequence id. Increments PDelay sequence ID and returns.On a local area networkit achieves clock accuracy in the sub-microsecond range, making it suitable for measurement and control systems.

InIEEE was released as a revised standard; also known as PTP Version 2, it improves accuracy, precision and robustness but is not backward compatible with the original version. It is also designed for applications that cannot bear the cost of a GPS receiver at each node, or for which GPS signals are inaccessible. The IEEE standards describe a hierarchical master-slave architecture for clock distribution. Under this architecture, a time distribution system consists of one or more communication media network segmentsand one or more clocks.

ptp neighbor rate ratio

An ordinary clock is a device with a single network connection and is either the source of master or destination for slave a synchronization reference. A boundary clock has multiple network connections and can accurately synchronize one network segment to another.

A synchronization master is selected for each of the network segments in the system. The root timing reference is called the grandmaster. The boundary clocks with a presence on that segment then relay accurate time to the other segments to which they are also connected. A simplified PTP system frequently consists of ordinary clocks connected to a single network, and no boundary clocks are used. A grandmaster is elected and all other clocks synchronize directly to it.

The transparent clock modifies PTP messages as they pass through the device. This scheme improves distribution accuracy by compensating for delivery variability across the network. PTP typically uses the same epoch as Unix time start of 1 January Synchronization and management of a PTP system is achieved through the exchange of messages across the communications medium.

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To this end, PTP uses the following message types. Messages are categorized as event and general messages. Event messages are time-critical in that accuracy in transmission and receipt timestamp accuracy directly affects clock distribution accuracy. General messages are more conventional protocol data units in that the data in these messages is of importance to PTP, but their transmission and receipt timestamps are not. A domain [i] is an interacting set of clocks that synchronize to one another using PTP.

Domains allow multiple clock distribution systems to share the same communications medium. The best master clock BMC algorithm performs a distributed selection of the best candidate clock based on the following clock properties:.

IEEE uses a hierarchical selection algorithm based on the following properties, in the indicated order: [8] : Figure The current clock master transmits this information at regular interval. A clock which considers itself a better master clock will transmit this information in order to invoke a change of master clock. Once the current master recognises the better clock, the current master stops transmitting Sync messages and associated clock properties Announce messages in the case of IEEE and the better clock takes over as master.

Clocks determine the offset between themselves and their master.

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The master periodically broadcasts the current time as a message to the other clocks. Under IEEE broadcasts are up to once per second. Under IEEEup to 10 per second are permitted. Not all masters have the ability to present an accurate timestamp in the Sync message. It is only after the transmission is complete that they are able to retrieve an accurate timestamp for the Sync transmission from their network hardware.

In order to accurately synchronize to their master, clocks must individually determine the network transit time of the Sync messages. The transit time is determined indirectly by measuring round-trip time from each clock to its master.

One assumption is that this exchange of messages happens over a period of time so small that this offset can safely be considered constant over that period. Another assumption is that the transit time of a message going from the master to a slave is equal to the transit time of a message going from the slave to the master.

ptp neighbor rate ratio

Finally, it is assumed that both the master and slave can accurately measure the time they send or receive a message. The degree to which these assumptions hold true determines the accuracy of the clock at the slave device. IEEE standard lists the following set of features that implementations may choose to support:.


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