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Peer DNS Address Resolution

The

Spacevars
0 series4

 supports defining a Diameter Peer by its IP address or using the Fully Qualified Domain Name (FQDN). In the latter case, the actual address is resolved through Domain Name System (DNS) queries. For each Diameter peer FQDN IP address resolution, the

Spacevars
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generates a maximum sequence of DNS query types: NAPTR, SRV, and A/AAAA. Depending on the FQDN prefix configuration, each Trunk Group is assigned a Policy and Charging Rule Function (PCRF) realm (pcrfRealm) with matching Diameter realm route. Traffic generated on these Trunk Groups is directed to the peers in their corresponding realm route. Similarly, DNS address resolution is directed to the Trunk Group's DNS server group with the same realm assignment.

Caption
0 Figure 1 DNS Query

 

Multiple IP Connections per Peer

The

Spacevars
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 supports multiple IP connections per Diameter Peer. If a set of IP addresses are returned, the

Spacevars
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 connects to all IP addresses under the same peer. The parameter, sessionDistribution, handles the session distribution order.   

The

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 Diameter capacity for this feature is as follows:

Caption
0 Table 1 SBC Diameter capacity
Parameter Maximum Capacity Diameter Node 1 Diameter Peers per Node 10 Diameter Realm Routes per Node 10 IP Connections per Peer 10 SRV Records Processed 5 Maximum Diameter Peer Connections (system-wide) 32

Note
IP connections (per peer) connect to the first 10 A/AAAA queried IP addresses, and the rest are ignored. SRV records process top five priority/weight records, and the rest are ignored.

Load Balancing Support Across Peers

Load Balancing for Static Peer

When using load balancing with a static peer configuration (when no DNS query is made and IP address is configured on the peer), the realmRoute configured for each peer must have the same priority to distribute the load evenly among all configured peers.

The example below demonstrates three peers with each peer associated with a realmRoute.

To exclude the peer from the load sharing. the corresponding realmRoute must be disabled (i.e to exclude peer d2 from load sharing, disable the realmRoute (realmRoute r2) associated with peer d2.

When realmRoute r2 is disabled, the load is evenly shared between d1 and d3.

Load Balancing for Dynamic Peer

For dynamic peer configuration (when DNS query is made to find the PCRF IP peer) and the SRV query results in multiple A records. To evenly distribute load among all peers, the peer sessionDistribution (addressContext default diamNode myDiamNode peer sessionDistribution) should be set to “round-robin”.

If one of the peer is down, the load gets automatically distribute among the remaining peers.

Info
For configuration details, refer to: EMA: Diam Node - Peer, Diam Peer Status CLI: Diameter Node - CLI