43: Configuring SAToP and CESoPSN
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© Virtual Access 2018
GW6600 Series User manual
Issue: 1.7
Page 485 of 519
43
Configuring SAToP and CESoPSN
SAToP and CESoPSN are supported on all hardware models that have synchronous serial
cards such as X.21, E1 and analogue Leased Line (LL).
43.1
What are SAToP and CESoPSN?
SAToP is an abbreviation for “Structure-Agnostic Time Division Multiplexing (TDM) over
Packet (SAToP)”. It is defined in IETF RFC4553 and is currently supported on Virtual
Access router models fitted with an E1 interface. It is used to carry an entire E1 signal
over a packet switched network.
CESoPSN is an abbreviation for “Circuit Emulation Services over Packet Switched
Network”. It is defined in IETF RFC5086 and is currently supported on Virtual Access
router models fitted with LL, X.21 or E1/T1 interfaces. It is used to carry an analogue
leased line, an X.21 interface, an E1 timeslot or a group of E1 timeslots over a packet
switched network.
Both SAToP and CESoPSN are pseudowire protocols.
43.2
Clocking
For the SAToP/CESoPSN function to work satisfactory it is essential that you synchronize
the clocks used for the TDM signals of the routers. That is, run at exactly the same
frequency, otherwise over-runs and under-runs in the packet buffers will occur.
Router models supporting SAToP/CESoPSN can use the following clock sources:
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Internal clock
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Clock recovered from E1 interface in TE mode
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Clock input on X.21 interface in DTE mode
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Clock recovered from pseudo-wire
When there is a SAToP or CESoPSN connection between two routers then one of them
should use clock recovered from pseudo-wire.
It is also necessary to configure the customer equipment correctly so that the same
clock is used by the two routers and two customer equipments.
Note:
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E1 interfaces in TE mode are clock slaves
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E1 interfaces in NT mode are clock masters
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X.21 interfaces in DTE mode are clock slaves
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X.21 interfaces in DCE mode are clock masters
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LL interfaces do not carry a clock
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Ensure you enable clock recovery on the clock slave only