Systems and methods for hardware-implemented anomaly detection in VLAN network using loopback port

1. A switch comprising:

a plurality of ports;

storage circuitry; and

control circuitry configured to:

determine whether a diagnostic mode is enabled for a given port of the plurality of ports, the given port being part of a virtual local area network (VLAN);

in response to determining that the diagnostic mode is enabled for the given port:

designate a port of the plurality of ports as a loopback port, wherein a packet transmitted on the loopback port is forwarded according to an entry of a forwarding database stored at the storage circuitry;

generate a layer 2 multicast index, stored at the storage circuitry, comprising an entry for the given port and an entry for the loopback port;

program the forwarding database with an entry for a destination address of the switch pointing to the layer 2 multicast index;

generate a diagnostic packet; and

transmit the diagnostic packet on the loopback port;

determine whether the diagnostic packet is received by any port of the plurality of ports; and

in response to determining that the diagnostic packet is received by any port of the plurality of ports, determine a network problem exists and cause a diagnostic protocol to execute.

2. The switch of claim 1 , wherein the control circuitry is further configured, when determining whether the diagnostic packet is received by any port of the plurality of ports, to:

determine whether an incoming diagnostic packet is received at any port of the plurality of ports other than the loopback port;

in response to determining that the incoming diagnostic packet is received at any port of the plurality of ports other than the loopback port, determine whether a destination address of the incoming diagnostic packet matches an address of the switch; and

in response to determining that the destination address of the incoming diagnostic packet matches the address of the switch, determine that the diagnostic packet is received by any port of the plurality of ports.

3. The switch of claim 1 , wherein the control circuitry is further configured, when generating the diagnostic packet, to:

program a source media access control (MAC) address of the diagnostic packet to be a MAC address of the switch;

program a destination MAC address of the diagnostic packet to be the MAC address of the switch with a multicast bit set; and

program the diagnostic packet to include a VLAN tag indicative of the VLAN.

4. The switch of claim 1 , wherein the control circuitry is further configured to regulate traffic flow for packets with a destination address set to be a media access control (MAC) address of the switch.

5. The switch of claim 4 , wherein the traffic flow is regulated by way of a meter whose rate is set to a range of 100-300 packets per second.

6. The switch of claim 1 , wherein the diagnostic mode is specifically enabled on the given port for the VLAN, and wherein the control circuitry is further configured to:

determine whether the VLAN is the only VLAN for which the diagnostic mode is enabled on the given port;

in response to determining that the VLAN is the only VLAN for which the diagnostic mode is enabled on the given port, monitor packets transmitted by way of the given port to the VLAN to determine, for each such packet, whether a rule is matched, the rule being as follows:

a media access control (MAC) destination address is set to be a MAC address of the switch with a multicast bit set, and

an outgoing port field is set to be an identifier for the given port; and

in response to determining that the rule is matched, insert, into a packet that matches the rule, an inner VLAN tag comprising a unique identifier for the given port.

7. The switch of claim 6 , wherein the control circuitry is further configured, in response to transmitting the diagnostic packet on the loopback port, to:

based on the entry of the forwarding database pointing to the layer 2 multicast index, replicate the diagnostic packet to both the given port and the loopback port, wherein the packet that matches the rule was replicated to the given port.

8. The switch of claim 1 , wherein the control circuitry is further configured to:

determine whether the diagnostic mode is enabled on a port additional to the given port on the VLAN; and

in response to determining that the diagnostic mode is enabled on the port additional to the given port on the VLAN, add the port additional to the given port to the layer 2 multicast index.

9. The switch of claim 1 , wherein the control circuitry is further configured to:

determine whether the diagnostic mode has been disabled on all ports of the plurality of ports that are in the VLAN; and

in response to determining that the diagnostic mode has been disabled on all ports of the plurality of ports that are in the VLAN, delete the layer 2 multicast index.

10. The switch of claim 9 , wherein the diagnostic protocol being executed causes:

a determination that a loop exists in the VLAN; and

a disabling of the loop by way of execution of a loop recovery action.

11. A method comprising:

determining whether a diagnostic mode is enabled for a given port of a plurality of ports of a switch, the given port being part of a virtual local area network (VLAN);

in response to determining that the diagnostic mode is enabled for the given port:

designating a port of the plurality of ports as a loopback port, wherein a packet transmitted on the loopback port is forwarded according to an entry of a forwarding database;

generating a layer 2 multicast index comprising an entry for the given port and an entry for the loopback port;

programming the forwarding database with an entry for a destination address of the switch pointing to the layer 2 multicast index;

generating a diagnostic packet; and

transmitting the diagnostic packet on the loopback port;

determining whether the diagnostic packet is received by any port of the plurality of ports; and

in response to determining that the diagnostic packet is received by any port of the plurality of ports, determining a network problem exists and causing a diagnostic protocol to execute.

12. The method of claim 11 , wherein determining whether the diagnostic packet is received by any port of the plurality of ports comprises:

determining whether an incoming diagnostic packet is received at any port of the plurality of ports other than the loopback port;

in response to determining that the incoming diagnostic packet is received at any port of the plurality of ports other than the loopback port, determining whether a destination address of the incoming diagnostic packet matches an address of the switch; and

in response to determining that the destination address of the incoming diagnostic packet matches the address of the switch, determining that the diagnostic packet is received by any port of the plurality of ports.

13. The method of claim 11 , wherein generating the diagnostic packet comprises:

programming a source media access control (MAC) address of the diagnostic packet to be a MAC address of the switch;

programming a destination MAC address of the diagnostic packet to be the MAC address of the switch with a multicast bit set; and

programming the diagnostic packet to include a VLAN tag indicative of the VLAN.

14. The method of claim 11 , further comprising regulating traffic flow for packets with a destination address set to be a media access control (MAC) address of the switch.

15. The method of claim 14 , wherein the traffic flow is regulated by way of a meter whose rate is set to a range of 100-300 packets per second.

16. The method of claim 11 , wherein the diagnostic mode is specifically enabled on the given port for the VLAN, and wherein the method further comprises:

determining whether the VLAN is the only VLAN for which the diagnostic mode is enabled on the given port;

in response to determining that the VLAN is the only VLAN for which the diagnostic mode is enabled on the given port, monitoring packets transmitted by way of the given port to the VLAN to determine, for each such packet, whether a rule is matched, the rule being as follows:

a media access control (MAC) destination address is set to be a MAC address of the switch with a multicast bit set, and

an outgoing port field is set to be an identifier for the given port; and

in response to determining that the rule is matched, inserting, into a packet that matches the rule, an inner VLAN tag comprising a unique identifier for the given port.

17. The method of claim 16 , further comprising, in response to transmitting the diagnostic packet on the loopback port:

based on the entry of the forwarding database pointing to the layer 2 multicast index, replicating the diagnostic packet to both the given port and the loopback port, wherein the packet that matches the rule was replicated to the given port.

18. The method of claim 11 , further comprising:

determining whether the diagnostic mode is enabled on a port additional to the given port on the VLAN; and

in response to determining that the diagnostic mode is enabled on the port additional to the given port on the VLAN, adding the port additional to the given port to the layer 2 multicast index.

19. The method of claim 11 , further comprising:

determining whether the diagnostic mode has been disabled on all ports of the plurality of ports that are in the VLAN; and

in response to determining that the diagnostic mode has been disabled on all ports of the plurality of ports that are in the VLAN, deleting the layer 2 multicast index.

20. The method of claim 19 , wherein the diagnostic protocol being executed causes:

a determination that a loop exists in the VLAN; and

a disabling of the loop by way of execution of a loop recovery action.