Cisco SCE8000 GBE - The Cisco SCE8000 GBE Optical Bypass; Optical Bypass Functionality; Optical Bypass Module Connectivity

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Cisco SCE8000 GBE Installation and Configuration Guide
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Chapter 2 Introduction to the Cisco SCE8000 GBE Platform
The Cisco SCE8000 GBE Optical Bypass
The Cisco SCE8000 GBE Optical Bypass
• Optical Bypass Functionality, page 2-10
• Optical Bypass Module (OPB-SCE8K-2L), page 2-11
The Cisco SCE8000 GBE platform optical bypass module preserves the service provider traffic links
under all circumstances. At power failure the bypass is automatically activated. It can also be activated
by the Cisco SCE8000 GBE software or hardware.
The Cisco SCE8000-SIP module already includes an internal electrical bypass, but it is strongly
recommended to use the optical bypass module for addressing the following scenarios:
• During platform reboot (SW reload)—If the external bypass module is not used, there is a 11-second
period during which the link is forced down (cutoff functionality). If any routing or spanning tree
protocols are used in the network, this delay may be extended.
• During a power failure —The Cisco SCE8000 GBE has two power supplies. A power failure occurs
only when both of them fail.
In a case where the Cisco SCE8000 GBE platform must be replaced, it is possible to remove the bypass
modules from the SCE8000 GBE chassis without disconnecting them from the network and then
reinstall them in the new SCE platform, so that traffic links are preserved even in a case of complete
failure and replacement of the Cisco SCE8000 GBE platform. (See Replacing the Optical Bypass
Module without Disrupting Traffic on the Link, page 9-28.)
Optical Bypass Functionality
The optical bypass module is connected bump-in-the-wire in the traffic link. It is then connected to the
Cisco SCE8000 GBE platform with two types of connections:
• GBE optical connections for data link traffic — connections from the optical bypass module to one
pair of the SPA ports.
• Control connection — Connection to the RJ-11 External Bypass connector on the SCE8000-SCM,
so the optical bypass is activated if the Cisco SCE8000 GBE platform fails.
“Y” RJ-11 control cables that control two optical bypass modules are provided with the SCE8000
GBE platform.
Optical Bypass Module Connectivity
The optical bypass module functions as follows:
• Under normal conditions, the bypass module directs traffic to flow via the Cisco SCE8000 GBE
GBE.
• Under failure conditions, the optical bypass shortcuts the interfaces that are connected to the traffic
link, and all traffic flows through the optical bypass module, bypassing the SCE platform.
Figure 2-6 displays the SCE8000 GBE optical bypass module connectivity.