Information About Asymmetric Routing Topology; Asymmetric Routing Topology; Asymmetric Routing And Other Service Control Capabilities - Cisco SCE 2000 Installation And Configuration Manual

Information About Topology Considerations
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

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Asymmetric Routing Topology

In some Service Control deployments, asymmetrical routing occurs between potential service control
insertion points. Asymmetrical routing can cause a situation in which the two directions of a
bi-directional flow pass through different SCE platforms, resulting in each SCE platform seeing only one
direction of the flow (either the inbound traffic or the outbound traffic).
This problem is typically solved by connecting the two SCE platforms in cascade mode (or through an
MGSCP cluster), thereby making sure that both directions of a flow run through the same SCE platform.
However, this is sometimes not feasible, due to the fact that the SCE platforms sharing the split flow are
geographically remote (especially common upon peering insertion). In this type of scenario, the
asymmetric routing solution enables the SCE platform to handle such traffic, allowing SCA BB to
classify traffic based on a single direction and to apply basic reporting and global control features to
uni-directional traffic.

Asymmetric Routing and Other Service Control Capabilities

Asymmetric routing can be combined with most other Service Control capabilities, however there are
some exceptions.
Service Control capabilities that cannot be used in an asymmetric routing topology include the
following:
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Cisco SCE 2000 4xGBE Installation and Configuration Guide
3-4
Asymmetric Routing Topology, page 3-4
Asymmetric Routing and Other Service Control Capabilities, page 3-4
Subscriber redirect
Subscriber notification
Any kind of subscriber integration, including MPLS VPN. (Use subscriber-less mode or anonymous
subscriber mode instead)
Classical open flow mode , including the following:
Flow-open-mode classical explicitly enabled (ROOT level configuration)
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VAS traffic forwarding mode enabled
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Analysis layer transport mode enabled (ROOT level configuration)
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– 'no TCP bypass-establishment' mode enabled (ROOT level configuration)
– A traffic rule is configured for certain flows to use the classical open flow mode (ROOT level
configuration)
Chapter 3 Information About Topology
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