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8.3.17.0 - Force10 Networks

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Configuration Source Election<br />

When an auto-upstream or auto-downstream port receives a DCB configuration from a peer, the port first<br />

checks to see if there is an active configuration source on the switch.<br />

• If a configuration source already exists, the received peer configuration is checked against the local<br />

port configuration. If the received configuration is compatible, the DCBX marks the port as<br />

DCBX-enabled. If the configuration received from the peer is not compatible, a warning message is<br />

logged and the DCBX frame error counter is incremented. Although DCBX is operationally disabled,<br />

the port keeps the peer link up and continues to exchange DCBX packets. If a compatible peer<br />

configuration is later received, DCBX is enabled on the port.<br />

• If there is no configuration source, a port may elect itself as the configuration source. A port may<br />

become the configuration source if the following conditions exist:<br />

• No other port is the configuration source.<br />

• The port role is auto-upstream.<br />

• The port is enabled with link up and DCBX enabled.<br />

• The port has performed a DCBX exchange with a DCBX peer.<br />

• The switch is capable of supporting the received DCB configuration values through either a<br />

symmetric or asymmetric parameter exchange.<br />

A newly elected configuration source propagates configuration changes received from a peer to the other<br />

auto-configuration ports. Ports receiving auto-configuration information from the configuration source<br />

ignore their current settings and use the configuration source information.<br />

Propagation of DCB Information<br />

When an auto-upstream or auto-downstream port receives a DCB configuration from a peer, the port acts<br />

as a DCBX client and checks if a DCBX configuration source exists on the switch.<br />

• If a configuration source is found, the received configuration is checked against the currently<br />

configured values that are internally propagated by the configuration source. If the local configuration<br />

is compatible with the received configuration, the port is enabled for DCBX operation and<br />

synchronization.<br />

• If the configuration received from the peer is not compatible with the internally propagated<br />

configuration used by the configuration source, the port is disabled as a client for DCBX operation and<br />

synchronization and a syslog error message is generated. The port keeps the peer link up and continues<br />

to exchange DCBX packets. If a compatible configuration is later received from the peer, the port is<br />

enabled for DCBX operation.<br />

Note: When a configuration source is elected, all auto-upstream ports other than the configuration source<br />

are marked as willing disabled. The internally propagated DCB configuration is refreshed on all<br />

auto-configuration ports and each port may begin configuration negotiation with a DCBX peer again.<br />

64 | Data Center Bridging (DCB)

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