Load Information Conveyance [RFC8583] AVPs

Diameter Load Information Conveyance (RFC8583)

This interface defines a mechanism to convey load information in Diameter networks, addressing specific requirements from [RFC7068] that are not fulfilled by the existing Diameter Overload Indication Conveyance (DOIC) mechanism [RFC7683]. In particular, it meets the needs for enabling load-balancing decisions and for providing load-level indications even when overload conditions are not present, thereby assisting nodes in proactively preventing overload.

Purpose of the Diameter Load Information Conveyance Interface

• Enhanced Load Awareness: The mechanism provides Diameter nodes with additional load information that goes beyond overload reports. This data enables load-balancing nodes to divert messages from overloaded upstream nodes to alternative nodes with greater capacity, addressing critical requirements (REQ 23 and REQ 24) from [RFC7068].
• Proactive Overload Prevention: By conveying load levels even in non-overload conditions, the mechanism assists nodes in making informed routing decisions to prevent overload from occurring. This proactive approach ensures a more stable network environment and improves the overall distribution of traffic.

Key Elements:

• Piggybacking of Load AVPs: Similar to DOIC, load information is conveyed by piggybacking specific Load AVPs onto existing Diameter messages. However, unlike DOIC, there is no capability negotiation; nodes simply include load data with the expectation that supporting nodes will utilize it in their routing decisions.

Two Types of Load Reports:

• Host-Load Report: Contains the load information of the endpoint sending the answer message and is transmitted end-to-end. This report is used by any Diameter node making server selection decisions.
• Peer-Load Report: Intended for use by Diameter nodes to select the next-hop peer. This report is removed by the first supporting node that processes it, making it effective only for local routing decisions.

Load Value Specification:

• The load report includes a value, ranging from 0 to 65535, indicating the relative load of the sending node. The value is designed to be consistent with DNS SRV weight values, where a higher Diameter Load value reflects a lower load (e.g., a node with zero load reports a value of 65535, while a fully loaded node reports 0).

Implementation Considerations:

• The distribution algorithm, the method for calculating the Load value, and the frequency of sending load reports are left as implementation decisions. The goal is to ensure that all nodes have a sufficiently accurate view of the load to support effective server selection and load-balancing, much in the same way as DNS SRV-based mechanisms.

For complete technical specification of Diameter Routing Message Priority please refer to: [RFC8583]

package com.mobius.software.telco.protocols.diameter.primitives.rfc8583