Some CDN service providers leverage Equal Cost Multi-Path (ECMP) routing in the POPs. ECMP is a stateless hash-based method of routing packets across multiple equal paths wherein each caching server acts as a next hop in the routing path. A problem occurs when servers are either added or removed from a pool of available servers in the POP. In such a case, the hashing function can misroute packets. Additionally, a TCP layer on the servers can misconstrue the packet as being at the correct destination, which can result in a dropped connection.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a system according to one embodiment including a content-delivery network (CDN) having multiple POPs with servers for gossiping connection state and packet re-distribution between host server computers.
FIG. 2 is a system diagram showing further details of a POP with intra-domain packet re-distribution and inter-domain packet redistribution.
FIG. 3 shows details of a host server computer that generates a pre-computed header template based upon a gossip message related to a connection state.
FIG. 4 is a flowchart according to one embodiment for identifying host server computers available on a POP.
FIG. 5 is a flowchart according to one embodiment for generating gossip messages.
FIG. 6 is a flowchart according to one embodiment for receiving a gossip message, generating a pre-computed header and using the header to re-direct a network packet.
