1 chapter 5 (supplementary) zigbee multicast. 2 outline introduction upon receipt of a multicast...
TRANSCRIPT
1
Chapter 5 (Supplementary)
ZigBee Multicast
2
Outline
Introduction Upon Receipt of A Multicast Frame from The Next
Higher Layer Member Mode Multicast
Initiating A ‘Member Mode’ Multicast Upon Receipt of A Member Mode Multicast Frame
Non-Member Mode Multicast Initiating A ‘Non-Member Mode’ Multicast Upon Receipt of A Non-member Mode Multicast Frame
Research Issues
3
Introduction Multicast addressing is accomplished by 16-bit multicast group ID
s. A multicast group is a collection of nodes
Registered under the same multicast group ID. Physically separated by a hop distance of no more than MaxNon
MemberRadius. Each node has a group ID Table
Contains a set of 16-bit group identifiers to which the device belongs.
nwkGroupIDTable is an attribute of the NIB (Network Information Base).
Attribute ID Type Read Only Range Description Default
nwkGroupIDTable 0x99 Set No Variable The set of group identifiers, in the
range 0x0000-0xffff, for groups of
which this device is a member.
Null Set
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Introduction (Cont.) ‘Member Mode’
The original message was created by a member of the group.
Relayed by means of broadcasts. ‘Non-Member Mode’
The original message was created by a non-member of the group.
Relayed by means of unicasts towards a group member.
Once reaching any member, switch to ‘Member Mode’.
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Basic Idea of ZigBee Multicast
N MN
N
N
N
MM
N
N
N
M
N
M
N
Non-membermode
(unicast)
Membermode
(k-hop broadcast)Membermode
(k-hop broadcast)
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Example
M
M
M
N
N
N
N
N
N
broadcast
broadcast
broadcastbroadcast
broadcast
Member mode multicast
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Example
MN
Non-Member mode multicast
N
unicast unicast
Switch to member mode and broadcast N
N
N
M
M
M
M
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Upon Receipt of A Multicast Frame from the Higher Layer
NLDE-DATA.request is received from its next higher level and the DstAddrMode is 0x01.
An entry exists in the nwkGroupIDTable?
Yes : Initiating a Member Mode Multicast
No : Initiating a Non-member Mode Multicast
0x01 implies this is Group ID, not address
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Member Mode Multicast
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Initiating A Member Mode Multicast
Set the multicast mode sub-field of the multicast control field to 0x01 (member mode).
If the BTT (Broadcast Transmission Table) is full and contains no expired entries.
The message shall not be sent. Issue the NLDE-DATA.confirm primitive with a Status value of BT_TABL
E_FULL. If the BTT is not full or contains an expired BTR (Broadcast Transmission R
ecord) Create a new BTR. Transmit the message.
0x01
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Upon Receipt of A Member Mode Multicast Frame Compare the sequence number and the source
address of the multicast frame with the records in its BTT.
If the device has a BTR of this multicast frame
discard the frame (duplicate message!) If no record is found and the BTT is full and contains no
expired entries
discard the frame (buffer full!) If no record is found and the BTT is not full or contains an
expired BTR
(OK!) create a new BTR, then continue processing (see the next page).
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Upon Receipt of A Member Mode Multicast Frame (Cont.) An entry exists in the nwkGroupIDTable?
Yes : (I am a member!) Pass the message to the next higher layer. Set the multicast mode sub-field of the multicast control field to
0x01 (member mode). Set the value of the NonmemberRadius sub-field to the value
of the MaxNonmemberRadius sub-field in the multicast control field.
Re-broadcast the frame. No : (I am not a member!)
Examine the frame's multicast NonmemberRadius field. 0 discard the frame along with the newly added BTR. Otherwise decrease NonmemberRadius field by 1 and re-broad
cast the frame.
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Upon Receipt of A Member Mode Multicast Frame (Cont.)
Each member mode multicast message shall be transmitted nwkMaxBroadcastRetries times and delay a period of nwkPassiveAckTimeout seconds between retransmissions.
The NWK layer issues an MCPSDATA.request primitive to the MAC sub-layer. DstAddrMode parameter set to 0x02 (16-bit network a
ddress). DstAddr parameter set to 0xffff.
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Example
M
N
MaxNonmemberRadius = 3 Current NonmemberRadius = 1
•NonmemberRadius = 1
•Entry isn’t found in nwkGroupIDTable
•Decrease NonmemberRadius to 0
•NonmemberRadius = 0
•Entry isn’t found in nwkGroupIDTable
•Discard the frame
N
•NonmemberRadius = 0
•Entry is found in nwkGroupIDTable
•Set NonmemberRadius to MaxNonmemberRadius (3)
A member mode multicast frame with NonmemberRaduis = 1
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Non-Member Mode Multicast
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Initiate a Non-Member Mode Multicast Set the multicast mode sub-field of the multicast control field to 0x00
(non-member mode). An entry corresponding to the GroupID destination in the routing tabl
e? Yes : examine the entry's status field (a route exists!)
If the status is ACTIVE, then transmit the frame. If the status is VALIDATION_UNDERWAY, then change the status to
ACTIVE and transmit the frame. Issue the NLDEDATA.confirm primitive with the Status value received
from the MCPSDATA.confirm primitive. No : (no route exists!)
DiscoverRoute parameter is 0x00 : Discard the frame Issue the NLDE-DATA.confirm primitive with a Status value of ROUTE_DI
SCOVERY_FAILED. DiscoverRoute parameter is 0x01 :
Initiate route discovery
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Upon Receipt of A Non-member Mode Multicast Frame An entry exists in the nwkGroupIDTable?
Yes : (I am a member!) Set multicast control field to 0x01 (member mode). The message shall be processed as if it had been received as
a member mode multicast. No : (I am not a member!) check its routing table for an entry
corresponding to the GroupID destination No such entry discard the frame. (There would be a record i
n routing table if we had initiated a non-member mode multicast frame and we had tried to find a route)
Otherwise examine the entry's status field. If the status is ACTIVE, then the device shall (re)transmit the frame. If the status is VALIDATION_UNDERWAY, then the status shall be change
d to ACTIVE and the device shall (re)transmit the frame. Issues an MCPSDATA.request primitive to the MAC sublayer.
DstAddrMode set to 0x02 (16-bit network address) DstAddr parameter set to the next hop as determined from the matching
routing table entry.
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Example
MN N
unicast unicastbroadcast
•Entry isn’t found in nwkGroupIDTable
• Route to GroupID destination is available
•Forward to the next hop according to the routing table
•Entry isn’t found in nwkGroupIDTable
• Route to GroupID destination is available
•Forward to the next hop according to the routing table
•Entry is found in nwkGroupIDTable
• Switch to member mode multicast
A non-meber mode multicast frame
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Summary: Research Issues
Some unspecified parameters. MaxNonmemberRadius nwkMaxBroadcastRetries nwkPassiveAckTimeout
Membership maintenance Join/Leave a multicast group.