Cisco Systems 4500 SVI Autostate, User-Based Rate Limiting, Unidirectional Ethernet, Unidirectional Link Detection

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Software Configuration Guide—Release 15.0(2)SG
OL-23818-01
Chapter 1 Product Overview Layer 2 Software Features
SVI Autostate
When an SVI has multiple ports on a VLAN, normally the SVI will go down when all the ports in the
VLAN go down. You can design your network so that some ports are not counted in the calculation of
SVI “going up or down.” SVI Autostate provides a knob to mark a port so that it is not counted in the
SVI “going up and down” calculation and applies to all VLANs that are enabled on that port.
User-Based Rate Limiting
User-Based Rate Limiting (UBRL) enables you to adopt microflow policing to dynamically learn traffic
flows and rate limit each unique flow to an individual rate. UBRL is available only on the Supervisor
Engine V-10GE with the built-in NetFlow support.
For information about UBRL, see the “Configuring User-Based Rate-Limiting” section on page 37-37.
Note Microflow is only supported on Supervisor Engine V-10GE.
Unidirectional Ethernet
Note Unidirectional Ethernet is not supported on either Supervisor Engine 6-E, Supervisor 6L-E, Catalyst
4900M, or Catalyst 4948E.
Unidirectional Ethernet uses only one strand of fiber for either transmitting or receiving one-way traffic
for the Gigaport, instead of two strands of fiber for a full-duplex Gigaport Ethernet.
For information about Unidirectional Ethernet, see Chapter 29, “Configuring Unidirectional Ethernet.”
Unidirectional Link Detection
The Unidirectional Link Detection (UDLD) protocol allows devices connected through fiber-optic or
copper Ethernet cables to monitor the physical configuration of the cables and detect a unidirectional
link.
With standard UDLD, the time to detect a unidirectional link can vary from a few seconds to several
minutes depending on how the timers are configured. Link status messages are exchanged every couple
of seconds. With Fast UDLD, you can detect unidirectional links in under one second (this also depends
on how the timers are configured). Link status messages are exchanged every couple of hundred
milliseconds.
For information about UDLD and Fast UDLD, see Chapter 28, “Configuring UDLD.”