Hi,
Here are my views regarding your query.
RE based sampling limitations:
- Since RE is handling all the control traffic on the router, we cannot configure very aggresive sampling rate as it will result in RE CPU getting over utilized resulting in instability.
- Routing Engine based sampling is not supported on VPN routing and forwarding (VRF) instances.
PFE based or inline sampling restrictions and limitations:
- You can configure inline sampling only on MX Series routers that have Trio-based line cards.
- You can apply Version 9 flow template only to IPv4 traffic.
- You can configure only one sampling instance on an Flexible PIC Concentrator (FPC).
- You can configure only one type of sampling–either PIC-based sampling or inline sampling–per family in a sampling instance. However, you can configure PIC-based and inline sampling for different families in a sampling instance.
- You can configure only one collector for inline sampling.
The following considerations apply to the inline flow-monitoring instance configuration:
- Sampling run-length and clip-size are not supported.
- For inline configurations, each family can support only one collector.
- Inline sampling instances can handle only up to 65536 AS paths. If the total number of AS paths exceed the maximum limit, the AS paths that have AS index greater than 65536 are discarded and counted as error. Flow records associated with such AS paths show the AS value as 0xFFFFFFFF . However, this limitation does not impact normal forwarding operations.
- On routers with Multiservices PICs or Multiservices DPCs, all fragments of a fragmented IPv4 packet other than the first fragment of the packet are processed accurately by the flow monitoring application running on MS-PIC or MS-DPC. The flow monitoring mechanism handles such fragments accurately by setting the layer 4 related fields in the associated flows to zero.
For more details, please refer to following links:
Hope this helps.
If this post was helpful, please mark this post as an "Accepted Solution".
Kudos are always appreciated!
Thanks