Port Management
Configuring Green Ethernet
167 Cisco 500 Series Stackable Managed Switch Administration Guide Release 1.3
10
Advertise Capabilities Negotiation
802.3az EEE support is advertised during the Auto-Negotiation stage. Auto-
Negotiation provides a linked device with the capability to detect the abilities
(modes of operation) supported by the device at the other end of the link,
determine common abilities, and configure itself for joint operation. Auto-
Negotiation is performed at the time of link-up, on command from management, or
upon detection of a link error. During the link establishment process, both link
partners to exchange their 802.3az EEE capabilities. Auto-Negotiation functions
automatically without user interaction when it is enabled on the device.
NOTE If Auto-Negotiation is not enabled on a port, the EEE is disabled. The
only exception is if the link speed is 1GB, then EEE still e enabled even though
Auto-Negotiation is disabled.
Link Level Discovery for 802.3az EEE
In addition to the capabilities described above, 802.3az EEE capabilities and
settings are also advertised using frames based on the organizationally-specific
TLVs defined in Annex G of IEEE Std 802.1AB protocol (LLDP). LLDP is used to
further optimize 802.3az EEE operation after auto-negotiation is completed. The
802.3az EEE TLV is used to fine tune system wake-up and refresh durations.
Availability of 802.3az EEE
Please check the release notes for a complete listing of products that support EEE.
Default Configuration
By default, 802.3az EEE and EEE LLDP are enabled globally and per port.
Interactions Between Features
The following describe 802.3az EEE interactions with other features:
• If auto-negotiation is not enabled on the port, the 802.3az EEE operational
status is disabled. The exception to this rule is that if the link speed is
1gigabyte, EEE still be enabled even though Auto-Negotiation is disabled.
• If 802.3az EEE is enabled and the port is going Up, it commences to work
immediately in accordance with the maximum wake time value of the port.
• On the GUI, the EEE field for the port is not available when the Short Reach
Mode option on the port is checked.
• If the port speed on the GE port is changed to 10Mbit, 802.3az EEE is
disabled. This is supported in GE models only.
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