Madge Networks Token Ring Switch - Manual (Page 55)

55
Smart DeskStream Technical Presentation 55
n DeskStream supports IEEE
n DeskStream participates in negotiation
Spanning Tree
IEEE Spanning Tree Support
Ring Number 101
IEEE SPT
X
DeskStream CRF and BRF send out and respond
to IEEE spanning tree frames
CRF
BRF
Ring Number 102
CRF to BRF link has a very low path cost to avoid
blocking within the DeskStream
Blocking will therefore occur at backbone port
In a more complex resilient network the CRF/BRF takes part in the
bridging conversations since it is a bridge. The responses to
Spanning Tree management frames is completely normal and so will
it will depend on path cost, ring number or MAC address as to which
ports are designated or standby (forwarding or blocking).
Note on internal blocking:
This is not a problem if the only BRF port is an uplink, but ALL BRF
ports will use this interface, so if it is blocking this may impact other
connections - dual attached servers for instance? If the BRF or Local
interface blocks it may result in the majority of traffic taking a longer,
less efficient route.
For that reason, it is important that all blocking/standby ports are
external to the DeskStream i.e. in a Ringswitch.