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MNLB packets not being processed by Forwarding Agents

Troubleshooting


Problem

z/OS is sending MultiNode Load Balancing (MNLB) packets with a TTL of 4. The packets are not being processed by the Forwarding Agents on the routers.

Cause

PQ97846 changed the z/OS Service Manager to send MNLB packets with a TTL of 4 instead of 1. z/OS 1.7 and later releases will always send MNLB packets with a TTL of 4. The MNLB packets are multicast to the forwarding agents. Since the TTL is greater than 1, the forwarding agents are first checking if they are configured to route multicast traffic. If they are not configured this way, the packets will be dropped.

Resolving The Problem

After applying PQ97846 or migrating to z/OS 1.7 or later, ip pim dense-mode must be configured on the Forwarding Agents to allow the MNLB packets to be processed.

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Document Information

Modified date:
15 June 2018

UID

swg21211426

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