Force10 Resilient Ring Protocol; Protocol Overview - Dell Force10 C150 Configuration Manual

Force10 Resilient Ring Protocol

Force10 Resilient Ring Protocol
The E-Series ExaScale platform is supported with FTOS 8.1.1.0 and later.
Force10 Resilient Ring Protocol (FRRP) provides fast network convergence to Layer 2 switches
interconnected in a ring topology, such as a Metropolitan Area Network (MAN) or large campuses. FRRP
is similar to what can be achieved with the Spanning Tree Protocol (STP), though even with optimizations,
STP can take up to 50 seconds to converge (depending on the size of network and node of failure) may
require 4 to 5 seconds to reconverge. FRRP can converge within 150ms to 1500ms when a link in the ring
breaks (depending on network configuration).
To operate a deterministic network, a network administrator must run a protocol that converges
independently of the network size or node of failure. The Force10 Resilient Ring Protocol (FRRP) is a
proprietary protocol that provides this flexibility, while preventing Layer 2 loops. FRRP provides
sub-second ring-failure detection and convergence/re-convergence in a Layer 2 network while eliminating
the need for running spanning-tree protocol. With its two-way path to destination configuration, FRRP
provides protection against any single link/switch failure and thus provides for greater network uptime.

Protocol Overview

FRRP is built on a ring topology. Up to 255 rings can be configured on a system. FRRP uses one Master
node and multiple Transit nodes in each ring. There is no limit to the number of nodes on a ring. The
Master node is responsible for the intelligence of the Ring and monitors the status of the Ring. The Master
node checks the status of the Ring by sending Ring Health Frames (RHF) around the Ring from its Primary
port and returning on its Secondary port. If the Master node misses three consecutive RHFs, it determines
the ring to be in a failed state. The Master then sends a Topology Change RHF to the Transit Nodes
informing them that the ring has changed. This causes the Transit Nodes to flush their forwarding tables,
and re-converge to the new network structure.
One port of the Master node is designated the Primary port (P) to the ring; another port is designated as the
Secondary port (S) to the ring. In normal operation, the Master node blocks the Secondary port for all
non-control traffic belonging to this FRRP group, thereby avoiding a loop in the ring, like STP. Layer 2
switching and learning mechanisms operate per existing standards on this ring.
is supported on platforms
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