Cisco Nexus 5000 Series Switch CLI Software Configuration Guide (OL-16597-01, July 2009)

• One side of a link remains up while the other side of the link is down
In these cases, the UDLD aggressive mode disables one of the ports on the link, which prevents traffic from
being discarded.
About Interface Speed
A Cisco Nexus 5000 Series switch has a number of fixed 10-Gigabit ports, each equipped with SFP+ interface
adapters. The Cisco Nexus 5010 switch has 20 fixed ports, the first 8 of which are switchable 1-Gigabit and
10-Gigabit ports. The Cisco Nexus 5020 switch has 40 fixed ports, the first 16 of which are switchable
1-Gigabit and 10-Gigabit ports.
About the Cisco Discovery Protocol
The Cisco Discovery Protocol (CDP) is a device discovery protocol that runs over Layer 2 (the data link layer)
on all Cisco-manufactured devices (routers, bridges, access servers, and switches) and allows network
management applications to discover Cisco devices that are neighbors of already known devices. With CDP,
network management applications can learn the device type and the Simple Network Management Protocol
(SNMP) agent address of neighboring devices running lower-layer, transparent protocols. This feature enables
applications to send SNMP queries to neighboring devices.
CDP runs on all media that support Subnetwork Access Protocol (SNAP). Because CDP runs over the data-link
layer only, two systems that support different network-layer protocols can learn about each other.
Each CDP-configured device sends periodic messages to a multicast address, advertising at least one address
at which it can receive SNMP messages. The advertisements also contain time-to-live, or holdtime information,
which is the length of time a receiving device holds CDP information before discarding it. Each device also
listens to the messages sent by other devices to learn about neighboring devices.
The switch supports both CDP Version 1 and Version 2.
Default CDP Configuration
The following table shows the default CDP configuration.
Table 8: Default CDP Configuration
Default SettingFeature
EnabledCDP interface state
60 secondsCDP timer (packet update frequency)
180 secondsCDP holdtime (before discarding)
EnabledCDP Version-2 advertisements
About the Debounce Timer Parameters
The port debounce time is the amount of time that an interface waits to notify the supervisor of a link going
down. During this time, the interface waits to see if the link comes back up. The wait period is a time when
traffic is stopped.
Cisco Nexus 5000 Series Switch CLI Software Configuration Guide
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Information About Ethernet Interfaces
About Interface Speed