Connectivity Guide

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.
Ring Health-
Check Frame
(RHF)
The Master node generates two types of RHFs. RHFs never loop the ring because they terminate at the
Master node’s secondary port.
● Hello RHF (HRHF) — These frames are processed only on the Master node’s Secondary port. The
Transit nodes pass the HRHF through without processing it. An HRHF is sent at every Hello interval.
● Topology Change RHF (TCRHF) — These frames contains ring status, keepalive, and the control
and member VLAN hash. The TCRHF is processed at each node of the ring. TCRHFs are sent out the
Master Node’s Primary and Secondary interface when the ring is declared in a Failed state with the
same sequence number, on any topology change to ensure that all Transit nodes receive it. There is
no periodic transmission of TCRHFs. The TCRHFs are sent on triggered events of ring failure or ring
restoration only.
Implementing FRRP
● FRRP is media and speed independent.
● FRRP is a Dell proprietary protocol that does not interoperate with any other vendor.
● You must disable the spanning tree protocol (STP) on both the Primary and Secondary interfaces before you can enable
FRRP.
● All ring ports must be Layer 2 ports. This is required for both Master and Transit nodes.
● A VLAN configured as a control VLAN for a ring cannot be configured as a control or member VLAN for any other ring.
● The control VLAN is not used to carry any data traffic; it carries only RHFs.
● The control VLAN cannot have members that are not ring ports.
Force10 Resilient Ring Protocol (FRRP)
335