Hi
Hoang and all,
I
have some comments and would like to seek clarification on 17.2.7.4. See
below:
17.2.7.4 Path
Management when HR-BS and HR-MS change role
An HR-BS changing its role as
HR-RS may select alternative path for subordinate HR-MS in the event of
disruption.
[WL]
It seems that there are multiple alternative paths prepared for a HR-MS, and
HR-BS selects one in the event of disruption. Is that correct?
[Hoang] Nope. There's only one alternative path for each HR-MS.
However, when HR-BS changing its role to HR-RS. This signal that there's a big
event in the network (e.g HR-BS loss backbone connection) that affect a lot of
HR-MS, and neighboring HR-BS. So the serving HR-BS may re-select new
alternative path for its subordinate HR-MS and the HR-MS may switch to its
alternative path.
The HR-BS may switch to the
alternative path.
[WL]
I think HR-MS should be the station switching to use the alternative path and
perform fast network re-entry, and the signaling is done by the
HR-BS.
[Hoang] Sorry, this is a typo mistake. It should be: "The HR-MS
may switch to the alternative path."
When an HR-MS changes its role as
RS or returns to HR-MS from RS mode, alternative path may be selected for
subordinate HR-MS.
[WL]
Two issues here: (1) It is not clear which station selects the alternative
path. For consistency, I propose that the signaling to be done by the serving
HR-BS. (2) According to the SRD, alternative paths are used for fast network
recovery in event of disruption. Returning to HR-MS from RS mode has nothing
to do with disruptions, so alternative paths are ill-defined for this
purpose.
[Hoang]: For (1) I totally agree with you. I'll change the wordings to make it
clear that HR-BS is in charge of alternative path. For (2), returning to HR-MS
from RS mode may render current alternative path (for its subordinate
HR-MS) in-valid, since there could be no RS serving subordinate HR-MS,
hence HR-BS may need to assign new alternative path to affected
HR-MS.
Regards,
Wai
Leong
From: Hoang Vinh Dien
[mailto:hvdien@NICT.COM.SG]
Sent: Thursday, May 05, 2011 10:23
AM
To: STDS-802-16@LISTSERV.IEEE.ORG
Subject:
[STDS-802-16] [802.16n] [MM] Proposed harmonized text for Path
management
Following the
teleconference discussion, I had revised the harmonized text for the path
management in three points:
1. Make clear that
Alternative path is determined by the HR-BS
2. Remove the
access station, replace by superordinate
Changes are in the
red in the text below. The track-change document can be found in the RG upload
directory, file name: C80216n-rg-11_0059r2.doc.
Please
have your comments on these.
[-------------------------------------------------Begin of Text
Proposal----------------------------------------------------]
17.2.7 Path Discovery and
Management
17.2.7.1 Alternative Path
Definition
An alternative path is used
for fast network recovery to a HR-MS in the event of disruption, e.g. when the
serving HR-RS or HR-BS fails. In normal operation, there are no active
connections on any alternative path. The alternative path will only be
activated when a single point of failure is
detected.
An alternative path is a link
or a list of continuous links between an HR-MS and the serving HR-BS, or an
alternative HR-BS. An alternative path is
determined by the serving HR-BS.
17.2.7.2 Alternative Path
Management
Alternative path management
consists of its establishment and maintenance, and the signaling for fast
network recovery when switching to the alternative
path.
The stations involved in the
alternative path management are the HR-MS, its superordinate and serving HR-BS, an
alternative superordinate and an alternative
HR-BS.
17.2.7.2.1 Alternative Path
Establishment
?
Serving HR-BS
? Choose an alternative path including mode change for of
its subordinate HR-MSs
? The algorithm and criteria for choosing the alternative
path: TBD
? Store alternative path
information
? Inform HR-MS of the path and path
information
?
Superordinate of HR-MS
? TBD
?
HR-MS
? Store Alternative Superordinate
? Store fast network re-entry
information
?
Alternative HR-BS (may be different from
serving HR-BS)
? Store alternative path
information
? Store HR-MS information
?
Alternative Superordinate
? Store HR-MS information
17.2.7.2.2 Maintenance of
Alternative Path
?
Serving
HR-BS
? Whenever an alternative path
is invalid or better alternative path is available
? Update alternative path
information for all HR-MS
? Inform HR-MS of the path and
path information
?
Superordinate of
HR-MS
? TBD
?
HR-MS
? Monitor alternative access
link
? Inform serving HR-BS
if alternative access link is unavailable
?
Alternative
HR-BS (may be different from serving HR-BS)
? TBD
?
Alternative
Superordinate
? Remove when alternative path
is not needed
17.2.7.2.3 Failure
Detection
The failure detection can be
performed by the stations around the point of failure and the reports from the
stations around the point of failure may be used for HR-BS?s decision to
establish the path using alternative path information. The detection procedure
and reporting messages is TBD.
17.2.7.3 Switching to
Alternative Path after SPOF
?
HR-MS
? Perform fast network
re-entry to alternative superordinate using stored
information
? Inform serving
HR-BS
?
Alternative
HR-BS (may be different from serving HR-BS)
? Allow network
re-entry
?
Alternative
Superordinate
? Allow network
re-entry
17.2.7.4 Path
Management when HR-BS and HR-MS change role
An HR-BS changing its role as
HR-RS may select alternative path for subordinate HR-MS in the event of
disruption. The HR-BS may switch to the alternative
path.
When an HR-MS changes its role as
RS or returns to HR-MS from RS mode, alternative path may be selected for
subordinate HR-MS.
[-------------------------------------------------End of Text
Proposal----------------------------------------------------]