Cisco SGE2000 Configuration Guide - Page 35

Chapter 3 Information About Topology Information About Topology Considerations In case the primary SCE 2000 fails, the two SCE 2000 s switch their roles, and this way fail-over is provided. Figure 3-5 Two SCE Platforms: Dual Link Inline Topology Subscriber Router Link 1 Router Network PWR A PWR B STATUS BYPASS LINK RX TX LINK RX TX Cisco SCE 2000 Series 4xGBE LINK RX TX LINK RX TX RX MM TX RX MM TX GBE-1 SUB LINE NET RX MM TX RX MM TX GBE-2 SUB LINE/CASCADE NET PWR A PWR B STATUS BYPASS LINK RX TX LINK RX TX Cisco SCE 2000 Series 4xGBE LINK RX TX LINK RX TX RX MM TX RX MM TX GBE-1 SUB LINE NET RX MM TX RX MM TX GBE-2 SUB LINE/CASCADE NET 92800 Subscriber Router Link 2 Router Network This fail-over solution preserves the SCE 2000 functionality and the network link: • The two SCE 2000 s are simultaneously aware of the subscriber contexts, and subscriber states are constantly exchanged between them, such that if the primary SCE 2000 fails, the secondary can take over with minimum state loss. • When one SCE 2000 fails (depending on the type of failure) its link traffic is still bypassed to the functioning SCE 2000 and processed there, so the traffic processing continues for both the links. • The bypass of the traffic through the failed SCE 2000 is configurable, and the user may choose to always cutoff the line that goes through the failed SCE 2000 . In this case network redundancy protocols like HSRP are responsible for identifying the line cutoff and switching all the traffic to go through the functioning SCE 2000 . OL-7824-06 Cisco SCE 2000 4xGBE Installation and Configuration Guide 3-9