Cisco SGE2000 Configuration Guide - Page 29

Bypass Mechanism, Maintaining the Network Links vs Maintaining SCE 2000 Platform Functionality

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Chapter 3 Information About Topology Information About Topology Considerations Note that when the SCE 2000 is connected to the network through an optical splitter, a failure of the SCE 2000 does not affect the traffic flow, as the traffic continues to flow through the optical splitter. • Bypass Mechanism • Maintaining the Network Links vs Maintaining SCE 2000 Platform Functionality Bypass Mechanism The SCE 2000 includes a Network Interface Card with a bypass mechanism that is enabled upon SCE 2000 failure. In addition, when connected in-line it can also be enabled in normal operation to simultaneously bypass traffic flow to the other side and direct it internally for analysis. In this case it maintains "receive-only"-like monitoring functions, when control functionality is not required. The bypass card supports the following four modes: • Bypass - The bypass mechanism preserves the network link, but traffic is not processed for monitoring or for control. • Forwarding - This is the normal operational mode, in which the SCE 2000 processes the traffic for monitoring and control purposes. • Sniffing - The bypass mechanism preserves the network link, while in parallel allowing the SCE 2000 to process the traffic for monitoring only. • Cutoff - There is no forwarding of traffic, and the physical link is forced down (cutoff functionality at layer 1). Maintaining the Network Links vs Maintaining SCE 2000 Platform Functionality When a single SCE 2000 is deployed, the user may decide that in case of a failure, maintaining the network link is more important than providing the SCE 2000 functionality. In this scenario, when the SCE 2000 detects a failure that requires a reboot process for recovering, it immediately switches to Bypass mode, allowing all traffic to bypass the SCE 2000 . The SCE 2000 stays in Bypass mode maintaining the network link, albeit without SCE 2000 processing, until the SCE 2000 fully recovers from the failure and is ready to resume normal functioning. Alternatively, the user may decide that the SCE 2000 functionality is sufficiently crucial to require severing the link if the SCE 2000 platform fails. In this case, when the SCE 2000 detects a failure that requires a reboot process for recovering, it immediately switches to Cutoff mode, stopping all traffic flow. The SCE 2000 stays in Cutoff mode, halting all traffic, until it fully recovers from the failure and is ready to resume normal functioning. In Cutoff the physical interface is blocked, enabling the network device connected to the SCE 2000 to sense that the link is down. Information About Asymmetric Routing Topology • Asymmetric Routing Topology • Asymmetric Routing and Other Service Control Capabilities OL-7824-06 Cisco SCE 2000 4xGBE Installation and Configuration Guide 3-3

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3-3
Cisco SCE 2000 4xGBE Installation and Configuration Guide
OL-7824-06
Chapter 3
Information About Topology
Information About Topology Considerations
Note that when the
SCE 2000
is connected to the network through an optical splitter, a failure of the
SCE 2000
does not affect the traffic flow, as the traffic continues to flow through the optical splitter.
•
Bypass Mechanism
•
Maintaining the Network Links vs Maintaining SCE 2000 Platform Functionality
Bypass Mechanism
The
SCE 2000
includes a Network Interface Card with a bypass mechanism that is enabled upon
SCE
2000
failure. In addition, when connected in-line it can also be enabled in normal operation to
simultaneously bypass traffic flow to the other side and direct it internally for analysis. In this case it
maintains "receive-only"-like monitoring functions, when control functionality is not required.
The bypass card supports the following four modes:
•
Bypass
— The bypass mechanism preserves the network link, but traffic is not processed for
monitoring or for control.
•
Forwarding
— This is the normal operational mode, in which the
SCE 2000
processes the traffic
for monitoring and control purposes.
•
Sniffing
— The bypass mechanism preserves the network link, while in parallel allowing the
SCE
2000
to process the traffic for monitoring only.
•
Cutoff
— There is no forwarding of traffic, and the physical link is forced down (cutoff
functionality at layer 1).
Maintaining the Network Links vs Maintaining SCE 2000 Platform Functionality
When a single
SCE 2000
is deployed, the user may decide that in case of a failure, maintaining the
network link is more important than providing the
SCE 2000
functionality. In this scenario, when the
SCE 2000
detects a failure that requires a reboot process for recovering, it immediately switches to
Bypass mode, allowing all traffic to bypass the
SCE 2000
. The
SCE 2000
stays in Bypass mode
maintaining the network link, albeit without
SCE 2000
processing, until the
SCE 2000
fully recovers
from the failure and is ready to resume normal functioning.
Alternatively, the user may decide that the
SCE 2000
functionality is sufficiently crucial to require
severing the link if the
SCE 2000
platform fails. In this case, when the
SCE 2000
detects a failure that
requires a reboot process for recovering, it immediately switches to Cutoff mode, stopping all traffic
flow. The
SCE 2000
stays in Cutoff mode, halting all traffic, until it fully recovers from the failure and
is ready to resume normal functioning. In Cutoff the physical interface is blocked, enabling the network
device connected to the
SCE 2000
to sense that the link is down.
Information About Asymmetric Routing Topology
•
Asymmetric Routing Topology
•
Asymmetric Routing and Other Service Control Capabilities