Reference Guide

Important FRRP Points
FRRP provides a convergence time that can generally range between 150ms and 1500ms for Layer 2 networks.
The Master node originates a high-speed frame that circulates around the ring. This frame, appropriately, sets up or breaks
down the ring.
● The Master node transmits ring status check frames at specified intervals.
● You can run multiple physical rings on the same switch.
● One Master node per ring — all other nodes are Transit.
● Each node has two member interfaces — primary and secondary.
●
There is no limit to the number of nodes on a ring.
● Master node ring port states — blocking, pre-forwarding, forwarding, and disabled.
● Transit node ring port states — blocking, pre-forwarding, forwarding, and disabled.
● STP disabled on ring interfaces.
● Master node secondary port is in blocking state during Normal operation.
● Ring health frames (RHF)
○ Hello RHF: sent at 500ms (hello interval); Only the Master node transmits and processes these.
○ Topology Change RHF: triggered updates; processed at all nodes.
Important FRRP Concepts
The following table lists some important FRRP concepts.
Concept
Explanation
Ring ID Each ring has a unique 8-bit ring ID through which the ring is identified (for example, FRRP 101 and FRRP
202, as shown in the illustration in Member VLAN Spanning Two Rings Connected by One Switch.
Control VLAN Each ring has a unique Control VLAN through which tagged ring health frames (RHF) are sent. Control
VLANs are used only for sending RHF, and cannot be used for any other purpose.
Member VLAN Each ring maintains a list of member VLANs. Member VLANs must be consistent across the entire ring.
Port Role Each node has two ports for each ring: Primary and Secondary. The Master node Primary port generates
RHFs. The Master node Secondary port receives the RHFs. On Transit nodes, there is no distinction
between a Primary and Secondary interface when operating in the Normal state.
Ring Interface
State
Each interface (port) that is part of the ring maintains one of four states”
● Blocking State — Accepts ring protocol packets but blocks data packets. LLDP, FEFD, or other
Layer 2 control packets are accepted. Only the Master node Secondary port can enter this state.
● Pre-Forwarding State — A transition state before moving to the Forward state. Control traffic is
forwarded but data traffic is blocked. The Master node Secondary port transitions through this state
during ring bring-up. All ports transition through this state when a port comes up.
● Pre-Forwarding State — A transition state before moving to the Forward state. Control traffic is
forwarded but data traffic is blocked. The Master node Secondary port transitions through this state
during ring bring-up. All ports transition through this state when a port comes up.
● Disabled State — When the port is disabled or down, or is not on the VLAN.
Ring Protocol
Timers
● Hello Interval — The interval when ring frames are generated from the Master node’s Primary
interface (default 500 ms). The Hello interval is configurable in 50 ms increments from 50 ms to 2000
ms.
● Dead Interval — The interval when data traffic is blocked on a port. The default is three times the
Hello interval rate. The dead interval is configurable in 50 ms increments from 50 ms to 6000 ms.
Ring Status The state of the FRRP ring. During initialization/configuration, the default ring status is Ring-down
(disabled). The Primary and Secondary interfaces, control VLAN, and Master and Transit node information
must be configured for the ring to be up.
● Ring-Up — Ring is up and operational.
● Ring-Down — Ring is broken or not set up.
308 Force10 Resilient Ring Protocol (FRRP)