Joint IEEE-SA and ITU Workshop on Ethernet
Multipoint Ethernet Connection
Protection (MECP)
Taesik Cheung
Principal Researcher
ETRI
Geneva, Switzerland, 13 July 2013
MECP Overview
MECP is a study point of Q9/WP3.
Scope of MECP is to protect single rootedmultipoint (RMP) Ethernet connections in
Ethernet transport networks.
Contributions have been provided for a
mechanism based on G.8031 APS protocol
to support
1+1 and 1:1 protection
Per-tree and per-leaf protection
Geneva, Switzerland, 2 13 July 2013
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Problem Statements
G.8031 (APS) or G.8032
(R-APS) can be used
between root and each leaf
node.
Root node should process
multiple (R)-APS instances.
Root
Leaf 1
In case of a failure affecting
many leaf nodes, there
may be a need for many
(R)-APS instances to
switch-over simultaneously.
X
Switch
Leaf 2
Leaf 3
Root
Leaf 1
Geneva, Switzerland, 2 13 July 2013
Switch
Switch
Switch
Leaf 2
Leaf 3
n x APS
instances
Leaf n
n x R-APS
instances
Leaf n
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Use Cases of MECP
MECP could be used to
protect RMP
connections in a tree
network topology.
Potential use cases:
Mobile backhaul networks
Administrative networks
of provincial government
(Connection between leaf
nodes is not allowed.)
PTS
Working
tree
DU(1)
Single MECP
instance
Aggr.
Aggr.
DU(2)
DU(3)
Protection
tree
DU(m)
PTS: Packet Transport Switch, Aggr.: Aggregation switch, DU: Digital Unit
Geneva, Switzerland, 2 13 July 2013
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Per-tree Protection
A working tree is
protected by a dedicated
protection tree.
A single failure on the
working tree which affects
only a portion of the leaf
nodes causes the whole
traffic flowing on the
working tree to be switched
to the protection tree.
Geneva, Switzerland, 2 13 July 2013
L1
Working tree
L2
R
Protection tree
Working tree
Lm
X
L1
L2
R
Protection tree
Lm
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Per-leaf Protection
A working tree is
protected by a dedicated
protection tree.
In the event of a failure
on the working tree, perleaf protection switches
over the traffic that
belongs to the affected
leaf node.
Geneva, Switzerland, 2 13 July 2013
L1
Working tree
L2
R
Protection tree
Working tree
Lm
X
L1
L2
R
Protection tree
Lm
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A proposal to
base MECP protocol on G.8031
West node
East node
B
S
Working P2P EC
S
APS
B
Protection P2P EC
B: Bridge
S: Selector
APS
NR(0,0)
NR(0,0)
SF(1,1)
1-phase
APS Protocol
SF detected on working path
Set bridge/selector to
protection path
Send request
Accept request
NR(1,1)
Geneva, Switzerland, 2 13 July 2013
Set bridge/selector to
protection path
Send confirmation
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Per-tree protection architecture
Root node
Leaf node (1)
B
S
S
B
APS(R)
APS(L1)
Geneva, Switzerland, 2 13 July 2013
S
B
Working RMP EC
Root node has one bridge and
one selector.
Each leaf node has one bridge
and one selector.
Root node sends identical APS
messages to all the leaf nodes.
(using multicast DA)
Each leaf node sends APS
messages to the root node.
Protection RMP EC
Leaf node (2)
APS(L2)
Leaf node (m)
S
B
APS(Lm)
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Per-leaf protection architecture
N
W
Root node
P
Selector bridge
N
W
Leaf node (1)
Wr
B
S
W1~Wm
S
P1~Pm
P
Broadcast bridge
APS(L1)
Leaf node (2)
S
B
Working RMP EC
Protection RMP EC
Root node has one broadcast
bridge and multiple selectors.
Each leaf node has one bridge
and one selector.
Root node sends different APS
messages to each leaf nodes.
(using unicast DA)
Each leaf node sends APS
messages to the root node.
B
Pr
APS(R)
APS(L2)
Leaf node (m)
S
B
APS(Lm)
Wr: Working tree (root  all leaves) Wm: Working path (leaf m  root)
Pr: Protection tree (root  all leaves) Pm: Protection path (leaf m  root)
Geneva, Switzerland, 2 13 July 2013
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Issues under discussion
Architecture and mechanism for per-leaf
protection
Consideration on various triggers for per-tree
protection
Benefits of per-tree protection comparing with
per-leaf protection
Monitoring methods for working/protection tree
Trade-off in terms of processing/management
of per-tree protection vs. using N APS/R-APS
processes
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