Apparatus and methods for network analysis

1. An apparatus comprising a non-transitory machine readable storage medium including instructions that, when executed by a network analysis expansion card coupled to a host device over a PCI-Express bus, cause the network analysis expansion card to:

receive a network data item from a network and duplicate the network data item into a first network data item and a second network data item;

store, using a capture module, the first network data item on a storage device;

buffer, in an input buffer coupled to a statistics module on the network analysis expansion card, the second network data item;

repeat the receive, duplicate, store, and buffer steps so that the input buffer contains a plurality of second network data items;

select from the input buffer, by the statistics module, one out of every X second network data items of the plurality of second network data items to form a subset of the plurality of second network data items, wherein the X is greater than one and is determined based on a utilization percentage of the input buffer and a rate of change in utilization percentage of the input buffer; and

perform, on the host device, network analysis on the subset of the plurality of second network data items, wherein a result of the network analysis is sent back to the statistics module over the PCI-Express bus.

2. The apparatus of claim 1 , wherein the storage device is random-access memory (RAM), and the capture module uses Direct Memory Access (DMA).

3. The apparatus of claim 1 , wherein the storage device is a hard disk drive (HDD), and the capture module stores the first network data item to the hard disk drive (HDD) using Direct-to-Disk.

4. The apparatus of claim 1 , wherein the capture module requires no operations to be performed by a host processor in support of capturing the first network data item.

5. The apparatus of claim 1 , wherein the statistics module sends instructions to a host processor to perform network analysis on the subset of the plurality of second network data items.

6. The apparatus of claim 5 , wherein the instructions are sent over a PCI Express bus.

7. The apparatus of claim 5 , wherein the statistics module receives statistics from the host processor based on the network analysis.

8. A method comprising:

receiving, on a network analysis expansion card coupled to a host device over a PCI-Express bus, a network data item from a network;

duplicating, on the network analysis expansion card, the network data item into a first network data item and a second network data item;

storing the first network data item on a storage device;

buffering, in an input buffer coupled to a statistics module on the network analysis expansion card, the second network data item;

repeating the receiving, duplicating, storing, and buffering steps so that the input buffer contains a plurality of second network data items;

selecting, by the statistics module, one out of every X second network data items of the plurality of second network data items from the input buffer to form a subset of the plurality of second network data items, wherein the X is greater than one and is determined based on a utilization percentage of the input buffer and a rate of change in utilization percentage of the input buffer; and

analyzing the subset of the plurality of second network data items using the host device, wherein a result of the analyzing is sent back to the statistics module over the PCI-Express bus.

9. The method of claim 8 , further comprising pre-filtering the network data item before duplicating the network data item.

10. The method of claim 8 , further comprising pre-filtering the network data item based on one or more of the following: source node, network or transmission protocol, or network traffic interest.

11. The method of claim 8 , wherein storing the first network data item on a storage device is performed using Direct Memory Access (DMA).

12. A system comprising:

a processor contained within a host device;

a network analysis expansion card coupled to the host device over a PCI-Express bus, the network analysis expansion card comprising:

a receiving module receiving a network data item from a network and duplicating the network data item into a first network data item and a second network data item;

a capture module receiving, from the receiving module, the first network data item and storing the first network data item on a storage device;

an input buffer buffering the second network data item received from the receiving module, in parallel with the capture module receiving the first network data item, wherein the receiving and duplicating by the receiving module, the receiving by the capture module, and the buffering by the input buffer are repeated so that the input buffer contains a plurality of second network data items; and

a statistics module selecting, from the input buffer, one out of every X second network data items of the plurality of second network data items to form a subset of the plurality of second network data items, sending the subset of the plurality of second network data items to the host device to perform network analysis on the subset of the plurality of second network data items, and receiving a result of the network analysis from the host device over the PCI-Express bus, wherein the X is greater than one and is determined based on a utilization percentage of the input buffer and a rate of change in utilization percentage of the input buffer.

13. The system of claim 12 , further comprising a storage device, the storage device including at least one of the following arrays of hard disk drives coupled to the system: a redundant array of inexpensive devices (RAID) or just a bunch of disks (JBOD) array.