Path Protection - GE JungleMUX SONET Technical Practice

Path Protection

The TDM pipes connected in ring topologies offer the capability for traffic/route
diversity. Normally, unicast traffic is routed to the destination port through the
path with the fewer ETHER-1000/ETHER-100 hops and the broadcast/multicast
traffic is routed half way around the ring simultaneously in both clockwise and
counterclockwise directions in a "drop-and-continue" manner. If a failure occurs
in a JMUX unit, or a fiber is damaged, affected traffic will be automatically
rerouted to the other way around the ring typically within 5 ms.
Note: Path protection is carried out independently for each TDM pipe configured
and provisioned as a ring.
Physical ETHER-1000 unit redundancy can be achieved by equipping an
ETHER-1000 drop site with two ETHER-1000 units installed on separate
paddleboards. These units can either be installed on separate CBW ports (this
would assume establishing completely independent ETHER-1000 systems using
separate STS-1 channels), or on the same CBW ports (using two cascaded
ETHER-1000 units). At each ETHER-1000 drop site, an Ethernet station/LAN
would then be connected to both unit paddleboards through an external switch
with a protection-switching feature (e.g. Rapid Spanning Tree) enabled.
example of a fully redundant ETHER-1000 application at an OC-48 JungleMUX
node is shown in Figure 10.
When "redundant" ETHER-1000 units are simultaneously bridging the same
traffic, an Ethernet loop is created which can cripple the network if not
properly handled. Traffic must, therefore, be connected through an
external switch with a feature such as Spanning Tree or Rapid Spanning
Copyright  GE Multilin Inc. 2010-2012
CAUTION
Tree enabled.
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Issue 1.2
April 2012
Page 23
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