Statistical multiplexing of inline network tools

1. A method comprising:

receiving a data packet at a network ingress port of a packet broker connected to a network;

applying a packet-matching criterion to identify a predetermined sequence of inline network tools through which the data packet is to be guided;

determining that a tool egress port that corresponds to an inline network tool within the predetermined sequence of inline network tools is part of a trunk,

wherein the trunk includes a defined subset of tool egress ports that are coupled to corresponding inline network tools, and

wherein each tool egress port of the defined subset of tool egress ports is a member of a Virtual Local Area Network (VLAN) membership group;

hashing a field of the data packet to produce a hash value; and

guiding the data packet through the predetermined sequence of inline network tools, wherein said guiding includes

dispatching the data packet to a particular tool egress port of the predefined subset of tool egress ports based on the hash value,

translating an internal identifier added to the data packet to an external identifier before transmission of the data packet by the packet broker to each of the inline network tools, and

translating the external identifier to a different internal identifier of the packet broker each time the data packet is received by the packet broker at a tool ingress port coupled to one of the inline network tools.

2. The method of claim 1 , wherein said hashing and said dispatching cause a traffic flow to be guided through the corresponding inline network tools in a load-balanced manner.

3. The method of claim 1 , further comprising:

receiving user input that specifies the corresponding inline network tools; and

forming the trunk responsive to receiving the user input.

4. The method of claim 1 , wherein the data packet is dispatched to the particular tool egress port based on the hash value, each of the corresponding inline network tools being associated with a different hash value.

5. The method of claim 1 , wherein the field of the data packet is specified by a user.

6. The method of claim 1 , wherein the field is an Internet Protocol (IP) source field or an IP destination field.

7. A method comprising:

receiving a data packet at a network ingress port of a packet broker connected to a network;

identifying a sequence of inline network tools through which the data packet is to be guided;

determining that a tool egress port corresponding to an inline network tool within the sequence of inline network tools is part of a trunk that includes a defined subset of tool egress ports coupled to corresponding inline network tools;

hashing a field of the data packet to produce a hash value;

dispatching the data packet to a particular tool egress port of the defined subset of tool egress ports based on the hash value;

identifying egress ports through which the packet broker forwards data packets to inline network tools;

for each egress port, implementing an egress translation scheme that causes an internal identifier appended to each data packet by the packet broker to be translated to an external identifier before transmission to a corresponding inline network tool;

identifying ingress ports through which the packet broker receives data packets from the inline network tools; and

for each ingress port, implementing an ingress translation scheme that causes the external identifier appended to a particular data packet by the packet broker to be translated to a different internal identifier each time the particular data packet is received from one of the inline network tools in the sequence.

8. The method of claim 7 , wherein the data packet is guided through the sequence of inline network tools in accordance with a packet guiding arrangement.

9. The method of claim 7 , wherein each internal identifier assigned to a given data packet upon receipt by the packet broker is unique across all traffic flows received by the packet broker and all inline network tools coupled directly to the packet broker.

10. The method of claim 7 , further comprising:

continually monitoring whether each inline network tool within the trunk is in a non-functioning state.

11. A method comprising:

receiving a data packet at a network ingress port of a packet broker connected to a network;

identifying a sequence of inline network tools through which the data packet is to be guided;

determining that a tool egress port corresponding to an inline network tool within the sequence of inline network tools is part of a trunk that includes a defined subset of tool egress ports coupled to corresponding inline network tools;

hashing a field of the data packet to produce a hash value;

dispatching the data packet to a particular tool egress port of the defined subset of tool egress ports based on the hash value;

continually monitoring whether each inline network tool within the trunk is in a non-functioning state;

determining that a single inline network tool has entered the non-functioning state; and

redistributing the traffic flow between one or more remaining inline network tools within the trunk by

removing the single inline network tool from the trunk, and

removing the single inline network tool from a Virtual Local Area Network (VLAN) membership group that includes the corresponding inline network tools.

12. The method of claim 10 , further comprising:

determining a state of the trunk.

13. A method comprising:

receiving a data packet at a network ingress port of a packet broker connected to a network;

identifying a sequence of inline network tools through which the data packet is to be guided;

determining that a tool egress port corresponding to an inline network tool within the sequence of inline network tools is part of a trunk that includes a defined subset of tool egress ports coupled to corresponding inline network tools;

hashing a field of the data packet to produce a hash value;

dispatching the data packet to a particular tool egress port of the defined subset of tool egress ports based on the hash value; and

continually monitoring whether each inline network tool within the trunk is in a non-functioning state,

wherein the state of the trunk is determined to be functioning if a number of inline network tools within the trunk in the non-functioning state is lower than a specified threshold.

14. The method of claim 13 , wherein the state of the trunk is non-functioning if the number of inline network tools within the trunk in the non-functioning state is higher than the specified threshold.

15. The method of claim 14 , further comprising:

upon determining the trunk is in a non-functioning state, declaring the trunk as defective; and

readjusting egress translation schemes and ingress translation schemes implemented by the packet broker to avoid the corresponding inline network tools of the trunk.

16. A packet broker comprising:

a network port at which to receive data packets transmitted over a network to which the packet broker is connected;

a plurality of tool ports connected to a plurality of inline network tools that are external to the packet broker; and

a programmable switching fabric configured to:

identify a sequence of inline network tools through which a data packet received at the network port is to be guided;

determine that a tool port corresponding to an inline network tool within the sequence of inline network tools is part of a trunk that includes a defined subset of tool ports coupled to corresponding inline network tools;

hash a field of the data packet to produce a hash value;

dispatch the data packet to a particular tool port of the defined subset of tool ports based on the hash value;

translate an internal identifier added to the data packet to an external identifier before transmission of the data packet by the packet broker to each of the inline network tools; and

translate the external identifier to a different internal identifier of the packet broker each time the data packet is received by the packet broker at a tool ingress port coupled to one of the inline network tools.

17. The packet broker of claim 16 , wherein the programmable switching fabric is further configured to:

receive input indicative of a user request to form the trunk; and

responsive to receiving the input, form the trunk that includes the defined subset of tool ports.