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Comparison of designated and undesignated intercluster connectivity

Unlike undesignated intercluster connectivity between clusters in their respective default IPspaces, designated intercluster connectivity uses a non-default IPspace to contain the interactions that a cluster has with its peer. Understanding how connectivity differs helps you decide if you want to use designated intercluster connectivity.

Undesignated intercluster connectivity operates within the default IPspaces of the clusters. Because of the pair-wise full-mesh connectivity requirement within an IPspace, all of the intercluster LIFs of the two clusters in the cluster peer relationship must be able to connect to each other. This connectivity requirement does not allow separation of connectivity that storage service providers might need. You would have to introduce hardware, such as a router, into the network to separate intercluster connectivity between clusters.

Designated intercluster connectivity operates within a specified non-default IPspace on at least one of the clusters in the peer relationship. The requirement of pair-wise full-mesh connectivity still exists, but the connectivity is within the IPspace that each cluster defines for the peering relationship and not across IPspaces. This keeps the intercluster connectivity isolated from different IPspaces that a cluster might have with other peers and also reduces the scope of the full-mesh connectivity requirement. In this way, a storage service provider can control the intercluster connectivity separation that might be needed.

As an example, you want Cluster A to have a peering relationship with two other clusters, Cluster B and Cluster C. Additionally, you want the connectivity between Cluster A and Cluster B to be separate from the connectivity between Cluster A and Cluster C. To do this, you can create two IPspaces on Cluster A. The first IPspace, called ipspaceAB, will contain the intercluster LIFs of Cluster A that you want to use to communicate with Cluster B. Likewise, the second IPspace, called ipspaceAC, will contain the intercluster LIFs of Cluster A that you want to use to communicate with Cluster C.

The intercluster LIFs on Cluster B and Cluster C are contained in the default IPspaces of their respective clusters. It is not a requirement that these intercluster LIFs be in the default IPspace. These intercluster LIFs can be in the default IPspace or in their own designated IPspaces.

For the peering relationship between Cluster A, Cluster B, and Cluster C, Cluster A would use only those LIFs in IPspace ipspaceAB to communicate with Cluster B, and only those LIFs in IPspace ipspaceAC to communicate with Cluster C. There is no requirement that intercluster LIFs in Cluster B communicate with any other intercluster LIFs on Cluster A other than those in IPspace ipspaceAB, and no requirement that intercluster LIFs in Cluster C communicate with any other intercluster LIFs on Cluster A other than those in IPspace ipspaceAC.