Limitations

The following limitations apply for MCT peers to support intermediate router functionality. The limitations are due to load-sharing and fast convergence trade-offs.
  • PIM-DM is not supported.
  • A few packets may be lost during the convergence interval or forwarding duplication may occur.
  • An MCT client will do flow-based load-sharing, not per-packet load-sharing.
  • Traffic loss or duplication will occur when the keep-alive VLAN, CCP, or the ICL between MCT peers is not up.
  • Multicast routing configurations on a session VLAN is not supported and restricted in configuration.
  • The load will only be shared and may or may not be balanced across the CCEPs.
  • During the convergence interval, a few packets may be lost. In the case of recoveries, some packets may end up being forwarded by both cluster routers during the interval.
  • Both the MCT peers maintain the state for traffic and pull down traffic for all multicast flows from the core, whether or not the chassis is forwarding this stream to the local CCEP. This could potentially waste the bandwidth inside the core and on the uplink.
  • You can configure both MCT peers to do either PIM routing or multicast snooping in MCT VLANs. However, configuring one MCT peer to do PIM routing and the other to do multicast snooping in the same MCT VLAN is not supported.
  • A PIM neighbor on the CEP in an MCT VLAN is not supported if the MCT cluster is running PIM on the same MCT VLAN.
  • IPv6 multicast routing on MCT is not supported on MCT clusters.
  • If loose mode is configured without a keep-alive VLAN, packet forwarding will be unpredictable. It is therefore recommended not to use loose mode without a keepalive VLAN.
  • If a core device is not a MCT client, convergence may not be optimal during cluster peer reload or failover, or when the ICL lag flaps. For better convergence it is recommended that the core is also an MCT client.
  • When clients are PIMrouters, a momentary traffic spike may occassionally occur when an ICL lag flaps, or when a cluster peer rejoins after a reload.
Parent topic: PIM Over MCT Intermediate Router Functionality