NSX-T Edge Packet drops in a setup using Bridge Firewall configuration due to exhaustion of mbuf_pool_socket_0
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Article ID: 311845
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Updated On:
Products
VMware NSX
Issue/Introduction
Symptoms: 1) Intermittent packet drops are observed in an environment with High number of fragmented packets. 2) From the Edge node support bundle, users observe rx_nombufs on one or several physical ports less ./edge/physical-ports-stats | grep -iE "name|rx_misses|rx_nombufs" "name": "fp-eth0", "rx_misses": 29221, << "rx_nombufs": 205794159, <<
AND Users would observe that a lot of packets sitting in the fragmentation queue. less ./edge/fw-if-total-stats | grep frag "reason-queued-frag": 54917, << These 2 counters key identifiers of the issue "reason-other-frag": 54381, <<
Environment
VMware NSX-T Data Center 3.x VMware NSX-T Data Center
Cause
The fragmented packets share the same mempool as the other packets. In NSX-T 3.1.X and earlier versions, the fragmented packets may stay in reassembly queues, in which case the buffer is not returned to the pool. In an environment with a high fragmented packet count, this can deplete the mempool, resulting in packet drop due to exhaustion on mbufs.
Resolution
The Edge Datapath is optimized in the NSX-T 3.2.x and above to efficiently handle the fragmented packets.