Digital Equipment DECbridge 500, Problem Solving

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B–2 DECbridge 500/600 Series Problem Solving
Rule 1: PHY B of This Node accepts connection to PHY A of Other Node if:
•
PHY A of This Node is not connected, or
•
PHY A of This Node is connected to PHY B or PHY S of another node.
Rule 2
: PHY A of This Node accepts connection to PHY B of Other Node if:
•
PHY B of This Node is not connected, or
•
PHY B of This Node is connected to PHY A or PHY S of another node.
See also Note 2.
Rule 3
: PHY A of This Node accepts the connection to PHY M of Other Node if:
•
PHY B of This Node is not connected, or
•
PHY B of This Node is connected to PHY A or PHY S of another node.
See also Note 2.
Note 1 :
Backup tree connection (dual homing)
The connection of PHY B of This Node to PHY M of Other Node always takes precedence
over the connection of PHY A of This Node to PHY M of another node.
When a connection between PHY A of This Node and a PHY M or PHY B of another node
exists, it is disabled when PHY B of This Node connects to PHY M of Other Node.
If the connection breaks between PHY B of This Node and PHY M of Other Node, the con-
nection is reestablished between PHY A of This Node and PHY M of another node.
Note 2 :
Tree connections are preferred over dual ring connections
Tree connections are preferred over dual ring connections when only one of two connections
may be accepted.
The connection of PHY A or B of This Node to PHY M of Other Node always takes prece-
dence over the connection of the remaining PHY (A or B) of This Node to PHY A or PHY
B of another node.
The connection is disabled between the remaining PHY (A or B) of This Node and PHY A
or PHY B of another node when PHY A or PHY B of This Node connects to PHY M of Other
Node.