CANONICAL NAME (CNAME) HANDLING FOR GLOBAL SERVER LOAD BALANCING

• US 20100011120A1
• Filed: 07/20/2009
• Published: 01/14/2010
• Est. Priority Date: 08/07/2002
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Foundry Networks Incorporated (Broadcom, Inc.)
• Inventors: Kommula, Sunanda Lakshmi
• Granted Patent: US 10,193,852 B2
• Time in Patent Office: Days
• US Class Current: 709/235
• CPC Class Codes: H04L 61/4511 using domain name system [DNS]
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/1008 based on parameters of servers, e.g. available memory or workload monitoring of computer activity G06F11/30
• CPC Class Codes: H04L 67/101 based on network conditions
• CPC Class Codes: H04L 67/1012 based on compliance of requirements or conditions with available server resources
• CPC Class Codes: H04L 67/1021 based on client or server locations

Abstract

Canonical name (CNAME) handling is performed in a system configured for global server load balancing (GSLB), which orders IP addresses into a list based on a set of performance metrics. When the GSLB switch receives a reply from an authoritative DNS server, the GSLB switch scans the reply for CNAME records. If a CNAME record is detected and it points to a host name configured for GSLB, then a GSLB algorithm is applied to the reply. This involves identifying the host name (pointed to by the CNAME record) in the reply and applying the metrics to the list of returned IP addresses corresponding to that host name, to reorder the list to place the “best” IP address at the top. If the CNAME record in the reply points to a host name that is not configured for GSLB, then the GSLB sends the reply unaltered to the inquiring client.

Claims

1. A method of providing load balancing in a network, the method comprising:

checking, by a load balance switch, a domain name system (DNS) reply for an alias associated with a canonical name (CNAME) record; and

if the alias associated with the CNAME record is detected in said DNS reply by said checking, applying by said load balance switch a load balancing algorithm to a list of network addresses provided in the DNS reply.

2. The method of claim 1 wherein the list of network addresses provided in the DNS reply includes virtual IP addresses.

3. The method of claim 1, further comprising sending by said load balance switch the list of network addresses, having the load balancing algorithm applied thereto, to a client program.

4. The method of claim 1 wherein said applying the load balancing algorithm includes arranging, by said load balance switch, the network addresses in said list based on a set of performance metrics.

5. The method of claim 1, further comprising enabling said load balance switch to check said DNS reply for the alias associated with the CNAME record.

6. The method of claim 1 wherein the alias includes a common zone relative to the host name but a different host.

13. The method of claim 1 wherein the DNS reply is received by said load balance switch as a reply to a DNS query to resolve a name into a network address.

7. An article of manufacture, comprising:

a storage medium having instructions stored thereon that are executable by a load balance switch to;

check, by said load balance switch, a domain name system (DNS) reply for an alias associated with a canonical name (CNAME) record; and

if the alias associated with the CNAME record is detected in said DNS reply by said check, apply by said load balance switch a load balancing algorithm to a list of network addresses provided in the DNS reply.

8. The article of manufacture of claim 7 wherein the storage medium further includes instructions stored thereon that are executable by said load balance switch to:

send by said load balance switch the list of network addresses, having the load balancing algorithm applied thereto, to a client program.

9. The article of manufacture of claim 7 wherein the instructions to apply the load balancing algorithm to the list of network addresses include instructions executable by said load balance switch to:

arrange by said load balance switch the network addresses as an ordered list based on a set of performance metrics.

14. The article of manufacture of claim 7 wherein the DNS reply is received by said load balance switch as a reply to a DNS query to resolve a name into a network address.

10. An apparatus to provide load balancing in a network, the apparatus comprising:

a load balance switch including;

a parser to check a domain name system (DNS) reply for an alias associated with a canonical name (CNAME) record; and

a controller coupled to the parser, the controller being operative to, if the alias associated with the CNAME record is detected in said DNS reply by the parser, apply a load balancing algorithm to a list of network addresses provided in the DNS reply.

11. The apparatus of claim 10 wherein said load balance switch further includes a proxy module to receive the DNS reply, which is a reply to a DNS query to revolve a name, wherein the DNS reply to the DNS query is received by the proxy module from an authoritative domain name server.

12. The apparatus of claim 10 wherein the load balancing algorithm includes an arrangement of the network addresses provided in the received DNS reply as an ordered list based on a set of performance metrics.