SmartNA-X
™
1G/10G User Guide 1.4
©
2015 Network Critical Solutions Limited
Chapter
8
Working with the V-Line Module
About V-Line modules
V-Line
™
Modules allow inline tools to be integrated into a live network. The V-Line Module can be configured to bypass
a failed inline appliance to allow the network to continue running, or it can be configured to stop the live network if the
appliance is a critical component.
The V-Line Module provides V-Line
™
, Breakout, Aggregation and Egress TAP applications. Data passed through the
module ports preserves fragments and other illegal frames transparently. The V-Line module has flexible packet slicing
and packet injection capabilities, and supports standard port features for LFP, LMP, and TAP mode for the live network
ports (A, B) to preserve the network connections if the device loses power.
For safety, tools connected inline are continuously monitored for availability using heartbeat packets sent across the live
ports, passing through the inline tool along the way (heartbeat packets are removed by the system to prevent them being
transmitted onto the live network). If the heartbeat packets stop being received—meaning the inline tool is unavailable
—the system immediately switches into bypass mode and either connects the live ports to keep the network running or
disconnects the live ports from the network stopping all traffic on the network, depending on the bypass mode selected.
TAP mode on V-Line modules
TAP mode is available on V-Line modules on the
AB
port pair only. On these modules, the
AB
ports always have either
LFP or LMP enabled unless it is running in Egress mode. However, in V-Line mode, if the Reverse Bypass setting is
enabled this will break the
AB
link if there is a power outage. For more information, see
on page 43.
V-Line module functionality
The V-Line Module provides three primary areas of functionality, although there is some overlap in the normal usage. The
three functions are:
• a V-Line facility with heartbeat based protection switching
• a general TAP mode allowing breakout and aggregation tap operations
• an egress packet slicing mode
V-Line mode
In V-Line mode the V-Line module is dedicated to supporting an inline tool that sees and can optionally filter all traffic
flowing on the main live network.
The inline tool health is permanently monitored by the card by sending special heartbeat packets to it and watching to
make sure the tool passes these packets correctly. The heartbeat packets are added to the streams sent to the C and D tool
ports and are removed from the streams received from the C and D tool ports. Heartbeat packets are never allowed onto
the live data network
If, for any reason the network tool stops passing heartbeat packets in either direction, the card will consider this a tool
failure. Depending on whether auto-bypass or reverse-bypass has been configured in the TAP, a failed tool will either be
automatically bypassed or the network will be stopped.
Optionally, packets received on the live network ports (A, B) can be passed to other modules in the system with or without
slicing the packets to a pre-set length. The slicing length can be set independently for each port.