Administrator Guide
its own forwarding table, and sends a control frame to the Transit nodes, instructing them to clear their forwarding tables and re-
learn the topology.
During the time between the Transit node detecting that its link is restored and the Master node detecting that the ring is restored,
the Master node’s Secondary port is still forwarding trac. This can create a temporary loop in the topology. To prevent this, the
Transit node places all the ring ports transiting the newly restored port into a temporary blocked state. The Transit node remembers
which port has been temporarily blocked and places it into a pre- forwarding state. When the Transit node in the pre-forwarding
state receives the control frame instructing it to clear its routing table, it does so and unblocks the previously blocked ring ports on
the newly restored port. Then the Transit node returns to the Normal state.
Multiple FRRP Rings
Up to 255 rings are allowed per system and multiple rings can be run on one system.
More than the recommended number of rings may cause interface instability. You can congure multiple rings with a single switch
connection; a single ring can have multiple FRRP groups; multiple rings can be connected with a common link.
Member VLAN Spanning Two Rings Connected by One Switch
A member VLAN can span two rings interconnected by a common switch, in a gure-eight style topology.
A switch can act as a Master node for one FRRP group and a Transit for another FRRP group, or it can be a Transit node for both
rings.
In the following example, FRRP 101 is a ring with its own Control VLAN, and FRRP 202 has its own Control VLAN running on another
ring. A Member VLAN that spans both rings is added as a Member VLAN to both FRRP groups. Switch R3 has two instances of
FRRP running on it: one for each ring. The example topology that follows shows R3 assuming the role of a Transit node for both
FRRP 101 and FRRP 202.
Force10 Resilient Ring Protocol (FRRP)
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