84 CHAPTER 4: XRN CONFIGURATIONIf you configure the same entry in the same ROM group for devices of a fabric to bedifferent values, the entry values of all the conflicting devices will adopt that of theconflicting device with the smallest Unit ID when you synchronize the devices. Such amechanism eliminates configuration conflicts between the devices in a fabric.After the device configurations converge, you can collect RMON history and statisticsdata of any units from any switch in the fabric.ConfigurationCommands for RMON onXRNAfter the configurations of the switches in a fabric converge, you can use thefollowing commands to collect RMON data of the devices in the fabric.Clustering on XRN Through neighbor topology discovery protocol (NTDP), Clustering can collect theinformation about the connection relations of the devices in a network and candidatedevices, consequently maintaining and managing the cluster topology.With Clustering employed, the NTDP topology information collecting function isenabled by default on the management device of the cluster. And the timer is set to 1minute. A management device can also perceive in time any changes of the clustertopology caused by new devices being added to the cluster and determine thecandidate switches among the detected devices. By sending joining-request packetsto candidate switches, the management device also enables these devices to beplug-and-play.Peer Fabric PortDetectionAs the basis of the XRN function, the fabric topology management (FTM) modulemanages and maintains the entire topology of a fabric. The FTM module alsoimplements the peer fabric port detection function.A device can join a fabric only when the following conditions are met.n The number of the existing devices in the fabric does not reach the maximumnumber of devices allowed by the fabric.n The fabric names of the device and the existing devices in the Fabric are the same.n The software version of the device is the same as that of the existing devices in thefabric.n The device passes the security authentication if security authentication is enabledin the fabric.Work Flow of the PeerFabric Port DetectionFunctionAfter a switch is powered on, the FTM module releases device information of theswitch through the fabric ports. The device information includes UNIT ID, CPU MAC,device type ID, fabric port information, and all fabric configuration information. Thedevice information is released in the form of discovery packet (DISC). A new devicecan join a fabric only when its DISC packets pass the authentication performed by theexisting devices in the fabric.n If a fabric port of a switch is connected to a non-fabric port, the switch will notreceive DISC packets from the peer. In this case, the switch cannot join the fabric.Table 69 Configuration commands on RMON on XRNOperation Command DescriptionCollect the RMON statistics data ofa specified unitdisplay rmon statistics unitunit-idYou can execute the displaycommand in any view.Collect the RMON history data of aspecified unitsdisplay rmon history unitunit-id
