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10-8
Cisco ONS 15600 Reference Manual, R7.2
Chapter 10 Ethernet Operation
10.7 Gigabit EtherChannel/IEEE 802.3ad Link Aggregation
Figure 10-4 Autonegotiation
10.7 Gigabit EtherChannel/IEEE 802.3ad Link Aggregation
The end-to-end Ethernet link integrity feature can be used in combination with Gigabit EtherChannel
(GEC) capability on attached devices. The combination provides an Ethernet traffic restoration scheme
that has a faster response time than alternate techniques such as spanning tree rerouting, yet is more
bandwidth efficient because spare bandwidth does not need to be reserved.
The ASAP card supports all forms of link aggregation technologies including GEC, which is a Cisco
proprietary standard, and the IEEE 802.3ad standard. The end-to-end link integrity feature ASAP card
allows a circuit to emulate an Ethernet link. This allows all flavors of Layer 2 and Layer 3 rerouting to
work correctly with the ASAP card. Figure 10-5 illustrates GEC support.
Figure 10-5 ASAP Gigabit EtherChannel (GEC) Support
Although the ASAP card does not actively run GEC, it supports the end-to-end GEC functionality of
attached Ethernet devices. If two Ethernet devices running GEC connect through the ASAP card to an
ONS network, the ONS SONET side network is transparent to the EtherChannel devices. The
EtherChannel devices operate as if they are directly connected to each other. Any combination of parallel
circuit sizes can be used to support GEC throughput.
GEC provides line-level active redundancy and protection (1:1) for attached Ethernet equipment. It can
also bundle parallel data links together to provide more aggregated bandwidth. Spanning Tree Protocol
(STP) operates as if the bundled links are one link and permits GEC to utilize these multiple parallel
paths. Without GEC, STP permits only a single nonblocked path. GEC can also provide ASAP card-level
protection or redundancy because it can support a group of ports on different cards (or different nodes)
so that if one port or card has a failure, traffic is rerouted over the other port or card.
124486
Ethernet links
Autonegotiation
SONET network
Router Router
15xxx 15xxx
Autonegotiation
SONET Circuits
Gigabit EtherChannel
Gigabit EtherChannel
ONS Node
ONS Node