Example would be destination port going into STP non-fowarding, policy rule changes, etc. This happens when a rule that went into the formation of the flow has changed. This happens when no packet has hit the flow in 40 seconds. The layer of the flow (L2/元/L4) will depend on which apps (routing, policy, etc) are active.īut, the flow establishment is still based on old-fashioned learning of the MAC addresses. What specifically triggers the creation and tearing down of a TCP flow? SYN with no accompanying ACK, at the beginning? A RST or FIN at the end? Does Netflow operates bidirectionally? The DFE does not pay attention to TCP options when creating/tearing down flows.įlows (TCP or not) are created when a packet has the MAC DA learned on a port, and there are no rules to prevent that packet being switched to that port.Each record will have the stats for the period it covers. So if a flow is active for 75 minutes, we will generate a record at 30 minutes, another at 60 minutes, and another at 75 minutes (when it ages out). This defaults to 30 minutes, and can be set as low as 1 minute. It defines that if a flow is active for X minutes we will generate a netflow record for that flow every X minutes. How long do flows for UDP persist? Are records exported at the beginning and the end of the flow? Nothing unique for UDP.Īll flows exist until they age out or are torn down by firmware (see reply to #3).Is there a record exported when the flow is terminated? There is no unique Neflow processing for ICMP or any other types.Īs long as we have a hardware connection established for that flow we generate records as described below. Are records for ICMP exported? Is an ICMP flow terminated immediately or do they persist for a configurable period of time?.However, the destination IP address and optionally the UDP port may be configured. What defines the destination for the exported Netflow records? There is no default destination IP address, and the default destination UDP port is 2055.
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