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A Method for Load Balancing across Parallel APPN Extended Intersubnetwork Boundaries

IP.com Disclosure Number: IPCOM000013015D
Original Publication Date: 1999-Nov-01
Included in the Prior Art Database: 2003-Jun-12
Document File: 3 page(s) / 53K

Publishing Venue

IBM

Related People

Govind Sampathkumar: AUTHOR [+6]

Abstract

Problem Statement. Advanced Peer to Peer Networking (APPN) Extended Border Nodes (EBNs) as currently architected attempt to search for cross-subnet resources by using any available path(s). So, typically more than one search subprocedure exits the origin subnet if there are multiple exit points from the subnet. They also have the property that sessions are brought up across the intersubnet boundaries across which the search succeeded. Once a resource is found and its location is cached by the EBNs across the subnet boundaries, subsequent searches for that resource also traverse the same path. Because of this, subsequent sessions get setup across the same subnetwork boundaries. This can result in concentration of load on specific subnetwork boundary EBNs. This could be undesirable especially if this subnetwork boundary is known to be not the best available one. In a customer environment where multiple subnetwork boundaries have been defined and some sort of parallel connections are available for redundant connectivity, it is desirable to have a way of controlling which intersubnet boundary is used for setting up the sessions with which resources. The solution proposed in this disclosure addresses these problems, and under stable network conditions, guarantees deterministic search exit and session-setup through a user configured "preferred EBN", provisions configuring backup paths that will be used if there are failures in the preferred path, after recovery of preferred path from failure, the session-setup reverts back to across the preferred path automatically. The solution works by letting the customer select a "preferred exit EBN" for searching for a particular resource or a set of resources. This, the customer sets up by configuring the SRLs (Subnet Routing Lists) on each EBN in the subnet. Once the preferred exit EBNs are setup for the resources, the searches for those resources are made to exit the subnet via the preferred exit EBN. This in turn ensures that the sessions get setup across that boundary.

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  A Method for Load Balancing across Parallel APPN Extended Intersubnetwork Boundaries
Problem Statement.

Advanced Peer to Peer Networking (APPN) Extended Border Nodes (EBNs) as currently architected attempt to search for cross-subnet resources by using any available path(s). So, typically more than one search subprocedure exits the origin subnet if there are multiple exit points from the subnet. They also have the property that sessions are brought up across the intersubnet boundaries across which the search succeeded. Once a resource is found and its location is cached by the EBNs across the subnet boundaries, subsequent searches for that resource also traverse the same path. Because of this, subsequent sessions get setup across the same subnetwork boundaries. This can result in concentration of load on specific subnetwork boundary EBNs. This could be undesirable especially if this subnetwork boundary is known to be not the best available one. In a customer environment where multiple subnetwork boundaries have been defined and some sort of parallel connections are available for redundant connectivity, it is desirable to have a way of controlling which intersubnet boundary is used for setting up the sessions with which resources.

The solution proposed in this disclosure addresses these problems, and under stable network conditions, guarantees deterministic search exit and session-setup through a user configured "preferred EBN", provisions configuring backup paths that will be used if there are failures in the preferred path, after recovery of preferred path from failure, the session-setup reverts back to across the preferred path automatically.

The solution works by letting the customer select a "preferred exit EBN" for searching for a particular resource or a set of resources. This, the customer sets up by configuring the SRLs (Subnet Routing Lists) on each EBN in the subnet. Once the preferred exit EBNs are setup for the resources, the searches for those resources are made to exit the subnet via the preferred exit EBN. This in turn ensures that the sessions get setup across that boundary.

Main elements of the solution.

The following extensions to the current EBN architecture are necessary for this solution:

Redirection of searches to Native EBNs: Provide ability for EBNs to send SRL searches to native

EBNs for searches not received over an Inter-Subnet Transmission Group (ISTG). In the current architecture, this ability is present only for searches for which the EBN acts as the Network Node Server (NNS) for the OLU, which includes the case where the search is received over an ISTG. Search queuing for deterministic subnet search exit: EBNs receiving SRL searches from native EBNs

and having an outstanding search of the same Fully Qualified Procedure Correlation IDentifier (FQPCID) and Procedure Resubmit Number (PRN) -- but not the same PCID modifier -- that has exited the subnet, queue up the received searches behind the outstandin...