Extended Edge Switching Rings
Extended Edge Switching rings allow two Extended Edge Switching (VPEX) cascades to be joined together to form a control plane ring. If a link breaks or a bridge port extender (BPE) otherwise leaves, the remaining BPEs reform two data plane cascades, thus keeping both control and data plane connectivity to the controlling bridge (CB) alive. This provides a redundant connection from any BPE in the ring to the CB. This is especially useful in a wiring closet application where the BPEs are located in the closet, and the CB is located more centrally, and there are only two links wired from the CB to the closet. Each cascade is formed from the control plane perspective only; the data plane acts as if there were two cascades consisting of BPEs that are each present in only one cascade. You can only achieve full redundancy with redundant CBs (see Redundant Controlling Bridges).
Rings are not explicitly configured, but rather are detected and created automatically. A ring contains the BPEs that were used in its formation. The life of a ring is ended by either a configuration command that changes one or both cascades, or a reboot of the CBs.
To support a wiring closet with only two links, each BPE that directly connects to the CB connects with only one link in its MLAG. To support this capability without forcing you to reserve and not use a port on one of the CBs, ExtremeXOS supports “one-arm” MLAGs where one CB has a connection reserved, and the other does not (see One-Arm MLAGs). This allows MLAG operation as if one link were down, meaning that both CBs are able to switch to the MLAG. ExtremeXOS also supports regular cross-connected MLAG at the top of the ring.
Multiple rings are supported. However, each ring must be completely separate from all others. For example, a simple ring could be formed from a single CB ports 1:1 and 1:2, while a separate ring could be formed from ports 1:3 and 1:4. Multiple rings cannot otherwise intersect, except at the CB itself.
- A maximum of 8 BPEs per ring is supported.
- A ring can be formed from exactly one or two cascades. A cascade (or any part thereof) can be a part of at most one ring.
- Three-way MLAG is not supported.
For information about setting up a ring, see Configuring Extended Edge Switching Ring Topology.