Subject: [mpls-tp] (no subject)

From: [email-masked]
Date: Tue, 27 Jul 2010 11:02:46 +0800

Hi Maarten,

I have some questions about SD. Correct me if I'm wrong. Thanks! 

1) Frame/Packet loss (per priority) of one path/channel is used for 
checking SD, but protection for path/channel does not base on one 
priority.

2) in the future, maybe all packet links will run over OTN, but now, other 
interfaces(e.g. SDH, Ethernt) are being for thansport. It's worth to 
consider present state.

Thanks!

Regards,
Ma

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发件人:  [email-masked]
2010-07-15 上午 10:20
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主题
mpls-tp Digest, Vol 25, Issue 72

Curtis,

I agree with you that the standard values are better being changed for the
application you describe. The SDH/SONET equipment as you remember supports
that. In SONET equipment you could choose the poisson based error rate
method and configure e.g. 1E-9 or 1E-11 (detection may take some time) as 
SD
trigger, and in burst based error method configure a low number of EBs 
(e.g.
5%, 1%) as SD trigger.

OTN equipment also support configuration of the number of EBs per second 
to
determine a BAD second. But when all links run with E-FEC, then your frame
loss due to bit errors will be either 0, or >80% with essentially nothing 
in
between. From a soft fault (range of values, SD type) the frame loss due 
to
bit errors is becoming a hard fault (only two values (GOOD, BAD), SF 
type).

Frame loss (per priority) due to congestion can have a large range of
values; if your committed traffic is being dropped due to congestion, then
SD can be triggered when the FLR (per second, for M seconds) exceeds e.g. 
5%
or 10%.

In future all packet links will run over OTN and be protected with OTN FEC
(S-FEC and E-FEC). Possibly bit errors will not longer play a role and we
can/should ignore it as condition in our considerations for packet 
transport
performance. Only frame/packet loss due to congestion may/should be
considered as performance parameter.

Regards,
Maarten

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