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Hi
Mahesh,
The
packet latency specified for basic NxDS0 CESoPSN PWs is not related to the
latency of the signaling packets carrying CAS when this service is extended to
carry CAS. In fact, the notion of packet latency is not applicable to these
packets, since they are not transmitted periodically.
Extension of the Basic NxDS0 CESoPSN service with CAS
is based on the reference PE architecture described in Appendix B of RFC 5086.
It assumes that the Framer identifies the changes in the CE Application state
(specifically, change in the CAS bits associated with any of the DS0
channels comprising the basic NxDS0 service) and triggers transmission of the
signaling packet carrying the new state. A more detailed description of the
transmission logic of the signaling packets is given in Appendix A. This logic
provides for resilience against occasional loss of the signaling packets and
deterministic recovery of the CE application state upon recovery from the packet
loss state. In particular, this logic includes transmission of the signaling
packet when the (basic) CESoPSN PW has been set up. In order to meet this
requirement while using separate PWs for carrying TDM PW and CE application
signaling, the PW carrying the signaling packets must be set up before the PW
that carries TDM data.
Hopefully these notes address your
concerns.
Regards,
Sasha
Hi
All,
I have some doubts on
Extended NxDS0 CAS mode setup. I have listed them
below.
a.
Does the packet latency specified
for Basic NxDS0 holds good for Extended NxDS0 mode with CAS. Because, when we
say CAS, are we not trunk-specific.
b.
When ever we need CAS, the TDM
interface should be in multi frame mode. It can be 16 frames or 24 frames
based on E1 or T1 interface. But if we configure for 1 ms packet latency then
we are required to send data for each 8 frames as payload. But CAS retrieval
aligns to SF number of frames (16 or 24). Does this mean, do we need to send
previously stored CAS state.
c.
My second doubt is on two
pseudowires. One for CAS and one for data. How does the user see this. For
example, Does single configuration to enable two pseudowires is required or
separate configuration for two pseudowires is recommended. In the later case,
though they are configured in sequence for CAS pseudowire and data pseudowire,
do we need to enable them at same time. Can signaling PW become active first
and data PW after some time.
Regards,
Mahesh
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