Table Of Contents
X.25 Throughput Negotiation
Contents
Restrictions for X.25 Throughput Negotiation
Information about X.25 Throughput Negotiation
How to Configure X.25 Throughput Negotiation
Prerequisites
Examples
Configuration Examples for X.25 Throughput Negotiation
`Basic' example
`Never' example
Additional References
Related Documents
Technical Assistance
Command Reference
x25 subscribe throughput
X.25 Throughput Negotiation
This feature enables a router to negotiate X.25 throughput parameters on behalf of end devices, thereby making it possible for X.25 calls to reach devices that may not themselves be able to negotiate throughput.
History for the X.25 Throughput Negotiation Feature
Release
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Modification
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12.3(11)YN
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This feature was introduced.
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12.4(4)T
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This feature was integrated into Cisco IOS 12.4(4)T.
|
Finding Support Information for Platforms and Cisco IOS Software Images
Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn. You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel when presented with the login screen and then follow the instructions that subsequently appear.
Contents
•
Restrictions for X.25 Throughput Negotiation
•Information about X.25 Throughput Negotiation
•How to Configure X.25 Throughput Negotiation
•Configuration Examples for X.25 Throughput Negotiation
•Command Reference
Restrictions for X.25 Throughput Negotiation
This feature currently supports only basic throughput classes; extended throughput classes are not supported.
Information about X.25 Throughput Negotiation
In order for end devices in a network to support X.25 calls, they need to be able to negotiate X.25 throughput parameters. This feature enables a router to handle that negotiation on behalf of end devices that cannot do it themselves.
Figure 1
Router Negotiating Throughput Between a Network and an End Device
The router does this by stripping out or inserting values, as appropriate for each case, in the "throughput facility field" of the X.25 calls' setup and confirmed messages (specifically, in the Call Request, Incoming Call, Call Accepted, and Call Confirmed packets).
In order to insert values appropriately, the router interface connected to the end device must earlier have been configured with the input and output bit rates that are intended to be used by the eventual X.25 call.
The rules according to which the router removes or inserts those bit rates are set by the command x25 subscribe throughput, which can have three distinct states: no, basic or never. These forms of the command work as follows when the router receives a call from the network and forwards that call onward to the end device:
a. If the router has been configured by the command "no x25 subscribe throughput", it will make no change to the values it receives in the call's facility field. The router merely forwards the message, and those values, onward.
b. If the router has been configured by the "x25 subscribe throughput basic" form of this command, the router will insert the bit rate values previously configured on its interface into the call's facility field. (The only exception is when those values are larger than the call's values, in which case the router will leave the call's smaller values in place when it forwards the message.)
In cases when the router has substituted its own configured values for the values it detected in the incoming call, the router also reports those new values in a Call Confirmed packet back out through the network to the source device.
c. If the "x25 subscribe throughput never" form of the command has been entered, the router will remove the values it receives in the call's facility field. (And if the values previously configured on the router's interface are smaller than those contained in the call, the router will also replace the call's values with those smaller ones when it forwards the end device's Call Confirmed packet back out to the network.)
How these behavior rules apply to each possible case is presented in Table 1.
When calls originate not in the network but in the end device, this command's three states can have somewhat different results, which are detailed in Table 2.
Table 1 Router Treatment of Throughput Facility Field in Incoming Call*
Incoming call's `Call Request' packet
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Cisco IOS commands applied
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Results
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Is interface configured with throughput values?
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How is Serial Line's throughput subscription configured?
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Within `Incoming Call' packet
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Within `Call Confirmed' packet
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Contains throughput facility field
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YES:
"x25 facility throughput xxx yyy"
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no x25 sub throughput
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Facility field in message from network is sent to end device unmodified.
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End device includes no facility field in its Call Accepted packet to the router. And the router includes no facility field in the Call Confirmed packet it sends out to the network.
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x25 sub throughput never
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Router strips out facility field, then forwards message to end device.
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Router sends values out to network only if the values configured on its interface are smaller than those received in network call.
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x25 sub throughput basic
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Router compares values in message with those configured on its interface, and sends to end device the lower set.
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Router sends that lower set out to the network.
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Has no throughput facility field
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no x25 sub throughput
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No facility field sent to end device.
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No facility field sent out to network.
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x25 sub throughput never
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No facility field sent to end device.
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No facility field sent back out to network.
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x25 sub throughput basic
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Router inserts facility field into message, and forwards that to the end device.
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No facility field sent back out to network.
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Contains throughput facility field
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NO:
"no x25 facility throughput"
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no x25 sub throughput
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Facility field sent to end device.
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End device includes no facility field in its Call Accepted packet to the router. And the router includes no facility field in the Call Confirmed packet it sends out to the network.
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x25 sub throughput never
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Router strips out facility field, then forwards message to end device.
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No facility field sent back out to network.
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x25 sub throughput basic
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Facility field sent on to end device.
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No facility field sent back out to network.
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Has no throughput facility field
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no x25 sub throughput
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No facility field sent to end device.
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No facility field sent out to network.
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x25 sub throughput never
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No facility field sent to end device.
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No facility field sent back out to network.
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x25 sub throughput basic
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No facility field sent to end device.
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No facility field sent out to network.
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*Shaded rows (in PDF version) describe calls that contain no throughput facility field before they reach the router.
Table 2 Router Treatment of Throughput Facility Field in Outgoing Call*
Outgoing call's `Call Request' packet
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Cisco IOS commands applied
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Results
|
Is interface configured with throughput values?
|
How is Serial Line's throughput subscription configured?
|
Within outgoing `Call Request' packet
|
Within received `Call Confirmed' packet
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Contains throughput facility field
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YES:
"x25 facility throughput xxx yyy"
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no x25 sub throughput
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Router forwards facility field it receives in the end device's Call Request packet out to the network unmodified.
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Router forwards facility field it receives in the Call Confirmed packet from the network on to the end device unmodified.
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x25 sub throughput never
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Router refuses to forward call on to the network, and cancels it, sending back to the end device a Clear Request packet with the Cause Code field set to 3 (`3' stands for "Invalid Facility Request"). Router also sends to the end device a Diagnostic Code field set to 65 (which stands for "Facility Code Not Allowed").
|
x25 sub throughput basic
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Router compares values in message with those configured on its interface, and sends to network the lower set.
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Router sends that lower set to the end device, unless still different values are received in the Call Confirmed message from the network. In that case, the router forwards that network set to the end device.
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Has no throughput facility field
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no x25 sub throughput
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No facility field sent to network.
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No facility field sent to end device.
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x25 sub throughput never
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Router sends values configured on its interface out to the network.
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No facility field sent to end device.
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x25 sub throughput basic
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Router inserts facility field into message, and forwards that to the network.
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Router sends the inserted facility field to the end device.
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Contains throughput facility field
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NO:
"no x25 facility throughput"
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no x25 sub throughput
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Router forwards facility field it receives in the end device's Call Request packet out to the network unmodified.
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Router forwards facility field it receives in the Call Confirmed packet from the network on to the end device unmodified.
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x25 sub throughput never
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Router refuses to forward call on to the network, and cancels it, sending back to the end device a Clear Request packet with the Cause Code field set to 3 (`3' stands for "Invalid Facility Request"). Router also sends to the end device a Diagnostic Code field set to 65 (which stands for "Facility Code Not Allowed").
|
x25 sub throughput basic
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Facility field sent on to network.
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Facility field sent back to end device.
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Has no throughput facility field
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no x25 sub throughput
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No facility field sent to network.
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No facility field sent to end device.
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x25 sub throughput never
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No facility field sent to network.
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No facility field sent to end device.
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x25 sub throughput basic
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No facility field sent to network.
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No facility field sent to end device.
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*Shaded rows (in PDF version) describe calls that contain no throughput facility field before they reach the router.
How to Configure X.25 Throughput Negotiation
Prerequisites
If you will be choosing the "basic" option in Step 4 below, the interface should already have been configured with the appropriate throughput values by use of the command x25 facility throughput in out . [That command is documented in the Cisco IOS Release 12.0 Wide-Area Networking Command Reference, viewable online at
http://www.cisco.com/en/US/docs/ios/wan/command/reference/wan_book.html
SUMMARY STEPS
1. enable
2. configure terminal
3. interface interface-id
4. x25 subscribe throughput { never | basic }
5. exit
DETAILED STEPS
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Command or Action
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Purpose
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Step 1
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enable
Example:
Router> enable
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Enables privileged EXEC mode.
•Enter your password if prompted.
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Step 2
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configure terminal
Example:
Router# configure terminal
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Enters global configuration mode.
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Step 3
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interface interface-id
Example:
Router(config)# interface serial2/0
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Specifies the interface which is connected to the end device, and enters interface configuration mode.
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Step 4
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x25 subscribe throughput { never | basic }
Example:
Router(config-if)# x25 subscribe throughput basic
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Enables the router to negotiate X.25 throughput for the end device.
(In this example, the end device always expects the throughput facility field to be present in incoming call setup packets).
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Step 5
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exit
Example:
Router(config-if)# exit
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Exits interface configuration mode.
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Examples
In this example, the end device never expects the throughput facility field to be present in incoming
call setup packets:
Router# configure terminal
Router(config)# interface serial2/0
Router(config-if)# x25 subscribe throughput never
In this example, the end device always expects the throughput facility field to be present in incoming
call setup packets:
Router# configure terminal
Router(config)# interface serial0/0
Router(config-if)# x25 subscribe throughput basic
In this example, the active throughput negotiation capability on the just-illustrated interface (Serial
0/0) gets turned off:
Router(config)# interface serial0/0
Router(config-if)# no x25 subscribe throughput
Configuration Examples for X.25 Throughput Negotiation
`Basic' example
In this example, the end device always expects the throughput facility field to be present in Incoming Call packets. The router inserts its configured bit rate values—unless they are larger than the values in the incoming call.
Router# configure terminal
Router(config)# interface serial2/0
Router(config-if)# x25 facility throughput 300 300
Router(config-if)# x25 subscribe throughput basic
`Never' example
In this example, the end device never expects the throughput facility field to be present in Incoming Call packets. The router removes the facility field from incoming calls.
Router# configure terminal
Router(config)# interface serial2/0
Router(config-if)# x25 facility throughput 300 300
Router(config-if)# x25 subscribe throughput never
Additional References
The following provides a reference related to X.25 Throughput Negotiation.
Related Documents
Related Topic
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Document Title
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Configuring X.25 throughput facilities.
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Cisco IOS Release 12.0 Wide-Area Networking Command Reference, especially its chapter entitled, "X.25 and LAPB Commands".
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Technical Assistance
Description
|
Link
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The Cisco Technical Support website contains thousands of pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content.
|
http://www.cisco.com/techsupport
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Command Reference
This section documents a new command:
•x25 subscribe throughput
x25 subscribe throughput
To enable a router to negotiate X.25 throughput for end devices, use the x25 subscribe throughput command in interface configuration mode. To disable this feature, use the no form of this command.
x25 subscribe throughput {never | basic}
no x25 subscribe throughput
Syntax Description
never
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Use this keyword for devices connected to the router that never expect the throughput facility field to be in the incoming call setup packets.
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basic
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Use this keyword for devices connected to the router that always expect the throughput facility field to be present in the incoming call setup packets.
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Command Default
No X.25 throughput negotiation is performed by the router for end devices.
Command Modes
Interface configuration
Command History
Release
|
Modification
|
12.3(11)YN
|
This command was introduced.
|
12.4(4)T
|
This command was integrated into Cisco IOS Release 12.4(4)T.
|
Examples
In this example, the end device never expects the throughput facility field to be present in incoming call setup packets:
Router# configure terminal
Router(config)# interface serial2/0
Router(config-if)# x25 subscribe throughput never
In this example, the end device always expects the throughput facility field to be present in incoming call setup packets:
Router# configure terminal
Router(config)# interface serial0/0
Router(config-if)# x25 subscribe throughput basic
In this example, the active throughput negotiation capability on the just-illustrated interface (Serial 0/0) is disabled:
Router(config)# interface serial0/0
Router(config-if)# no x25 subscribe throughput
Related Commands
Command
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Description
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x25 facility throughput
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Specifies the input and output bit rate values that the router should insert into the call setup packets' throughput-facility field.
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x25 subscribe flow-control
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Configures inclusion of X.25 flow-control parameter negotiation facilities in call setup packets.
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Copyright © 2005 Cisco Systems, Inc. All rights reserved.
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