Specifications

ALAXALA Ring Configuration Guide (Edition 1)
Copyright © 2008, ALAXALA Networks Corporation. All rights reserved.
8
(3) Multi-ring configurations with shared links
When neighboring rings are connected at two or more nodes as contact points, multiple rings share a link. This
link is called a shared link, and a multi-ring configuration with this type of link is called a multi-ring
configuration with shared links.
When different VLANs are used for data frame transfer in each neighboring ring (VLAN-excluded), the rings
run as independent single rings. When a common VLAN is used for data frame transfer (VLAN-shared), the
rings perform failure detection and switching operations different from actions by the single ring configuration to
prevent a super loop
#
when failure occurs in the shared link.
In this VLAN-shared multi-ring configuration with shared links, one ring monitors failure and recovery from
failure on the shared link (shared link monitoring ring, or O-shaped ring), and the other rings do not monitor
failure and recovery from failure on the shared link (shared link non-monitoring ring, or C-shaped ring). The
nodes at both ends of the shared link are called shared nodes.
As described above, you can prevent a super loop due to a failure on the share link by making sure the rings do
not logically overlap.
# super loop:
This is a loop state across rings. A super loop occurs when neighboring rings are connected into a single ring without
any blocking points. This state occurs when the rings independently perform the same failure operations as the ones done
by single rings in response to a shared link failure.
(4) Configuration using the Ring Protocol and STP/GSRP together
The Ring Protocol supports combined use with the Spanning Tree Protocols (STPs) or with GSRP. A
configuration using the Ring Protocol with STP or GSRP is available in both single ring and multi-ring
configurations. You can also use the configuration with or without the shared link.
V
LAN-excluded
Multi-ring configurations with shared links
V
LAN-shared
Multi-ring configurations with shared links
O-shaped
ring
C-shaped
ring
When each ring on the right and left performs failure
operations as if each were in a single ring, both rings have
no blocking points and thus form a single large loop.
Configuration using the Ring
Protocol and STP
Ring STP
Configuration using the Ring
Protocol and GSRP
Ri
ng
GSRP