On Jun 11, 2009, at 9:22 PM, Jeff Bacon wrote:
Is there a good list of these caveats somewhere I can look at?
NetFlow:
256K mls tables at 93% efficiency (~233K entries).
No packet-sampled control of flow creation can lead to mls table
overflow & non-deterministic skewing of stats/heuristics; small mls
table size contributes to this in environments with diverse traffic
patterns and/or high pps, such as SP edge. NetFlow 'sampling' on
6500/7600 is actually NDE output telemetry sampling only, not the same
as packet-sampled control of flow creation on software platforms, GSR,
ASR 1K, CRS-1, N7K.
No logical OR of TCP flags observed throughout a TCP flow, only the
last flag.
No dropped traffic stats/heuristics.
ACLs:
ACLs must be carefully crafted to avoid LOU exhaustion & subsequent
software switching self-DoS:
<https://www.cisco.com/en/US/products/hw/switches/ps708/products_white_paper09186a00800c9470.shtml#wp43500
>
uRPF:
uRPF mode must be the same for all interfaces in a chassis.
Note that these are all edge features. These boxes are fine running
in the core and/or other areas in which these particular edge features
aren't required; it's the edge which can be problematic.
-----------------------------------------------------------------------
Roland Dobbins <[email protected]> // <http://www.arbornetworks.com>
Unfortunately, inefficiency scales really well.
-- Kevin Lawton
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