Cisco Cisco ONS 15454 SONET Multiservice Provisioning Platform (MSPP) Guía De Diseño

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 Some network devices can be configured to ignore a loss of carrier condition.  If such a 

device attaches to a G-Series card at one end then alternative techniques (such as use of Layer 
2 or Layer 3 protocol keep alive messages) are required to route traffic around failures.  The 
response time of such alternate techniques is typically much longer than techniques that use link 
state as indications of an error condition. 
 

Enabling or disabling port level flow control on the test set or other Ethernet device attached 

to the Gig-E port can affect the transmit (Tx) laser of the G-Series Ethernet card.  This can result 
in unidirectional traffic flow, if flow control is not enabled on the test set or other Ethernet device. 
 

 
The end-to-end Ethernet link integrity feature of G-Series cards can be used in combination with 
Gigabit EtherChannel capability on attached devices.  The combination provide an Ethernet traffic 
restoration scheme that has a faster response time than alternate techniques such as spanning 
tree re-routing, yet is more bandwidth efficient because spare bandwidth does not need to be 
reserved. 
 
G-Series Ethernet cards supports all forms of Link Aggregation technologies including Gigabit 
EtherChannel (GEC) which is a Cisco proprietary standard as well as the IEEE 802.3ad standard.  
The end-to-end link integrity feature of the G-Series cards allows a circuit to emulate an Ethernet 
link.  This allows all flavors of Layer 2 and Layer 3 re-routing, as well as technologies such as link 
aggregation, to work correctly with the G-Series cards.  The G-Series cards support Gigabit 
EtherChannel (GEC), which is a Cisco proprietary standard similar to the IEEE link aggregation 
standard (IEEE 802.3ad).  Figure 5-16 illustrates G-Series GEC support. 
 

 

 

 

 
Although G-Series cards do not actively run GEC, they do supports the end-to-end GEC  
functionality of attached Ethernet devices.  If two Ethernet devices running GEC connect through 
G-Series cards to an ONS 15454 network, the ONS 15454 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 Gig-E 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 Gig-E data links together to provide more aggregated bandwidth.  STP 
operates as if the bundled links are one link and permits GEC to utilize these multiple parallel