Alcatel-Lucent 7450 ESS Series, Configuration Manual

Page: 479 / 540

Cflowd
7450 ESS OS Router Configuration Guide Page 479
Operation
Figure 24 depicts the basic operation of the cflowd feature. This sample flow is only used to
describe the basic steps that are performed. It is not intended to specify implementation.
Figure 24: Basic Cflowd Steps
1. As a packet ingresses a port, a decision is made to forward or drop the packet.
2. If the packet is forwarded, it is then decided if the packet should be sampled for cflowd.
3. If a new flow is found, a new entry is added to the cache. If the flow already exists in the
cache, the flow statistics are updated.
4. If a new flow is detected and the maximum number of entries are already in the flow cache, the
earliest expiry entry is removed. The earliest expiry entry/flow is the next flow that will expire
due to the active or inactive timer expiration.
5. If a flow has been inactive for a period of time equal to or greater then the inactive timer
(default 15 seconds), then the entry is removed from the flow cache.
6. If a flow has been active for a period of time equal to or greater than the active timer (default
30 minutes), then the entry is removed from the flow cache.
copy of header sent to cflowd
HEADER
INFORMATION
PROCESSED
AND FLOW CACHE
UPDATED
INGRESS PORT
FORWARD/
DROP ?
SAMPLE?
FINISH FORWARDING
PROCESS AND SEND
TO EGRESS PORT
EGRESS PORT
drop
BIT BUCKET
NEW OR
EXISTING
FLOW
?
existing flow
new
flow
ADD ENTRY
FLOW CACHE
EXPORT
TO
COLLECTOR
UPDATE
ENTRY