Operator Switch Commands in PBBTE

1
Operator Switch Commands in PBB-TE

• Zehavit Alon
• IEEE Plenary Meeting November 2008

2
Definitions from G.8031

• Manual switch normal traffic signal to
  protection In the absence of a failure of a
  working or protection transport entity, forces
  normal traffic signal to be selected from the
  protection transport entity.
• Force switch normal traffic signal to protection
  Forces normal traffic signal to be selected
  from the protection transport entity.

3
State machines in G.8031 non-revertive
modeSignal Fail on working
4
Switch to Protection in non-revertive mode
Protection
Force Switch

• Start
• Force switch
• Working fails
• Working recovers
• Protection fails

Working
Manual Switch
Protection

• Start
• Manual switch
• Working fails
• Working recovers
• Protection fails

Working
Force switch command and manual switch command
have the same functionality in non-revertive mode
in G.8031 In PBB-TE, failure of the protection
entity after force switch will not result a
switchover to the working entity and traffic will
be lost, while in manual switch traffic will be
switched to working
5
State machines in G.8031 revertive modeSignal
Fail on working
6
Switch to Protection in revertive mode
Protection
Force Switch

• Start
• Force switch
• Working fails
• Working recovers

Working
Protection
Manual Switch

• Start
• Manual switch
• Working fails
• Working recovers

Working
In this case, the functionality of manual switch
is unexpected and not intuitive traffic is
restored to the working.
7
Suggestions

• EITHER
• Change the priority of MStoProtection to be
  higher than w.SF
• and
• Change the Clear manual Switch state machine so
  that w.SF will not clear MStoProtection
• OR
• Remove the manual switch command and leave only
  the force switch command as it is defined in the
  G.8031 so that p.SF has higher priority than FS.

8
Thank You

• zehavit.alon_at_nsn.com

9
Backup
10
State machines in G.8031
In revertive mode, the difference between force
switch and manual switch for local request
clear (h) is that the state changes to No
request (A) instead of Do Not Revert (H)
11
Conclusions

• There are differences between PBB-TE and G.8031
• In PBB-TE, the precedence of FS is higher than
  p.SF, while in G.8031, the precedence of p.SF is
  higher than FS.
• PBB-TE supports the manual switch to working
  command this is not supported in G.8031.
• PBB-TE supports the 11 protection scheme only,
  while G.8031 supports additional schemes, such as
  1N and 11.
• In G.8031, the only meaningful difference between
  manual switch and force switch is the
  non-intuitive difference in revertive mode
  functionality.
• If the working entity fails and recovers after a
  manual switch, traffic will be mapped to the
  working entity. However, after force switch it
  will remain in the protection entity.

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Differences between G.8031 and PBB-TE

• In G.8031, the switch command operates on the
  selector, while in PBB-TE there is no selector.
• There is no manual switch to working in G.8031.
• The precedence of p.SF and FS is inverted.

G.8031
PBB-TE