Chain topology
shows a chain topology in which data flows through the head port to all switches in the
chain. When a connection within the chain is broken, data flows through both the head
and tail ports to reach all switches in the chain.
Chain topology
Chain - Each switch can be head, tail or
member.
When the role is chain/head, one ring port is the head port and another is the
member port. In normal state, both ring ports are forwarded.
When the role is chain/tail, one ring port is the tail port and another is the
member port. The tail port is a redundant port. In normal state, the tail port is
blocked.
When the role is chain/member, both ring ports are member ports. In normal state,
both ring ports are forwarded.
Balancing Chain Topology
Balancing chain topology
shows a chain topology in which data flows through terminal ports at both ends to the
central block in the chain. When a connection within the chain is broken, data flows
along the chain to reach all switches in the chain.
Balancing chain topology
Balancing Chain - Each switch can be
central-block, terminal-1/2 or member.
When the role is
balancing-chain/central-block, one ring port is the member port and another is the
block port. The block port is a redundant port. In normal state, the block port is
blocked.
When the role is
balancing-chain/terminal-1/2, one ring port is the terminal port and another is the
member port. In normal state, both ring ports are forwarded.
When the role is
balancing-chain/member, both ring ports are member ports. In normal state, both ring
ports are forwarded.
Topology Change Notification (TCN)
When an ISW chain or balancing chain is restored after an interruption, the ISW switches
at the end of the chain generate a TCN BPDU packet. The packet is processed by the VSP
switches that are connected to the ISW chain, resulting in fast (less than 100ms)
network redundancy recovery time.
This feature provides the following benefits:
Fast recovery time.
When the chain topology changes, the VSP switches will fast age MAC addresses
learned on the VLANs extended into the ISW chains.
VSP switches connected to the same
chain no longer need to share a virtual interswitch trunk (vIST) to keep MAC
addresses synchronized across both switches.
This feature is present in firmware version v01.01.03.0013 or later. No configuration
steps are required to activate it on the ISW switches, and it works even though Spanning
Tree Protocol (STP) has been disabled on the ISWs in order to activate the RingV2
chain..
Note
On the VSP switches, Spanning Tree
must be enabled on the ports that connect to the ISW switches.
