Version 3.1 SP2 Reference Guide - Extreme Networks

Chapter 11Each of the two switches maintains the MLAG state for each of the MLAG ports and communicateswith the other to learn the MLAG states, MAC FDB, and IP multicast FDB of the peer MLAG switch.ISC Blocking FiltersThe ISC blocking filters are used to prevent looping and optimize bandwidth utilization. When at leastone MLAG peer port is active, the upper layer software initiates a block of traffic that ingresses the ISCport and needs to be forwarded to the local MLAG ports. This is considered to be the steady statecondition.In normal steady state operation most network traffic does not traverse the ISC. All unicast packetsdestined to MLAG ports are sent to the local MLAG port only. However, flood and multicast traffictraverses the ISC but is dropped from MLAG peer port transmission by the ISC blocking filtermechanism.The ISC blocking filter matches all Layer 2 traffic received on the ISC and blocks transmission to allMLAG ports that have MLAG peer ports in the active state. When there are no active MLAG peer ports,the upper layer software initiates an unblocking of traffic that ingresses the ISC port and needs to beforwarded to the local MLAG ports thus providing redundancy. This is considered to be the failed state.Inter-Switch CommunicationKeep-alive ProtocolMLAG peers monitor the health of the ISC using a keep-alive protocol that periodically sends healthcheckmessages. The frequency of these health-check hellos can be configured.MLAG Status CheckpointingEach switch sends its MLAG peer information about the configuration and status of MLAGs that arecurrently configured over the ISC link. This information is checkpointed over a TCP connection that isestablished between the MLAG peers after the keep-alive protocol has been bootstrapped.Viewing MLAG InformationYou can view information about an MLAG peer, including an MLAG peer switch state, MLAG groupcount, and health-check statistics.You can also view each MLAG group, including local port number, local port status, remote MLAG portstate, MLAG peer name, MLAG peer status, local port failure count, remote MLAG port failure count,and MLAG peer failure count.To see if a port is part of an MLAG group or an ISC port, complete the following steps:Ridgeline Reference Guide199