Redirection to a virtual router

• US 7,136,383 B1
• Filed: 03/18/2005
• Issued: 11/14/2006
• Est. Priority Date: 12/26/2000
• Status: Expired due to Fees

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Wilson, Ian
• Primary Examiner(s): Pham, Chi
• Assistant Examiner(s): JONES, PRENELL P
• Application Number:
  US11/083,727
• Time in Patent Office: 606 Days
• Field of Search: 370389-395, 370/351, 370/535, 370/331, 370401-402, 370/219, 370/229, 370/400, 709/245, 709/244, 709/202, 709/230, 709/231
• US Class Current: 370/392
• CPC Class Codes: H04L 12/56 Packet switching systems

Abstract

Methods and apparatus for sending a redirect packet to a host are disclosed. In a first router that supports a virtual router protocol, a method of sending a redirect packet to a host, the redirect packet notifying the host that specific packets are to be redirected to a second router, includes receiving a packet from a host, the packet including a source address identifying the host and a destination address identifying a destination network. The first router ascertains the destination network of the packet from the destination address and obtains from a routing table an address of a next router to the packet'"'"'s destination network. The first router then determines whether to send a redirect packet to the host. In accordance with one embodiment, this is performed by determining whether the next router and the host identified by the source address of the packet are on the same network. When it is determined that the next router and the host are on the same network, the first router composes and sends the redirect packet to the host. The redirect packet serves to notify the host that packets addressed to the destination network are to be redirected to a virtual address of the next router.

Claims

1. A first router that supports a virtual router protocol, the first router being capable of sending a redirect packet to a host, the redirect packet notifying the host that specific packets are to be redirected to a second router, comprising:

a processor; and

a memory, at least one of the processor and the memory being adapted for;

receiving a packet from the host, the packet including a source address identifying the host and a destination address identifying a destination network;

ascertaining the destination network of the packet from the destination address;

obtaining from a routing table an address of a next router that is coupled to the packet'"'"'s destination network;

determining whether the next router and the host identified by the source address of the packet are on the same network; and

when it is determined that the next router and the host are on the same network, composing the redirect packet notifying the host that packets addressed to the destination network are to be redirected to a virtual address of the next router and sending the redirect packet to the host;

wherein determining whether the next router and the host identified by the source address of the packet are on the same network comprises;

determining from the routing table that a next hop to reach the destination network is back out the same interface that the packet was received on.

2. A first router that supports a virtual router protocol, the first router being capable of sending a redirect packet to a host, the redirect packet notifying the host that specific packets are to be redirected to a second router, comprising:

a processor; and

a memory, at least one of the processor and the memory being adapted for;

receiving a packet from the host, the packet including a source address identifying the host and a destination address identifying a destination network;

ascertaining the destination network of the packet from the destination address;

obtaining from a routing table an address of a next router that is coupled to the packet'"'"'s destination network;

determining whether the next router and the host identified by the source address of the packet are on the same network; and

when it is determined that the next router and the host are on the same network, composing the redirect packet notifying the host that packets addressed to the destination network are to be redirected to a virtual address of the next router and sending the redirect packet to the host and

replacing an IP address of the next router in the redirect packet with the virtual address of the next router.

3. A first router that supports a virtual router protocol, the first router being capable of sending a redirect packet to a host, the redirect packet notifying the host that specific packets are to be redirected to a second router, comprising:

a processor; and

a memory, at least one of the processor and the memory being adapted for;

receiving a packet from the host, the packet including a source address identifying the host and a destination address identifying a destination network;

ascertaining the destination network of the packet from the destination address;

obtaining from a routing table an address of a next router that is coupled to the packet'"'"'s destination network;

determining whether the next router and the host identified by the source address of the packet are on the same network; and

when it is determined that the next router and the host are on the same network, composing the redirect packet notifying the host that packets addressed to the destination network are to be redirected to a virtual address of the next router and sending the redirect packet to the host;

wherein the virtual router protocol is VRRP or HSRP.

4. A first router that supports a virtual router protocol, the first router being capable of sending a redirect packet to a host, the redirect packet notifying the host that specific packets are to be redirected to a second router, comprising:

a processor; and

a memory, at least one of the processor and the memory being adapted for;

receiving a packet from the host, the packet including a source address identifying the host and a destination address identifying a destination network;

ascertaining the destination network of the packet from the destination address;

obtaining from a routing table an address of a next router that is coupled to the packet'"'"'s destination network;

determining whether the next router and the host identified by the source address of the packet are on the same network; and

when it is determined that the next router and the host are on the same network, composing the redirect packet notifying the host that packets addressed to the destination network are to be redirected to a virtual address of the next router and sending the redirect packet to the host;

wherein the redirect packet is an ICMP redirect.

5. A first router that supports a virtual router protocol, the first router being adapted for sending a redirect packet to a host, the redirect packet notifying the host that packets to be sent to a particular network are to be redirected to a second router, comprising:

a processor; and

a memory, at least one of the processor and the memory being adapted for;

determining whether to send a redirect packet to a primary IP address of the second router or to a virtual IP address of the second router, the virtual IP address being associated with one or more routers;

when it is determined to send a redirect packet to the primary IP address of the second router, composing a redirect packet indicating that packets to be sent to a specific network are to be redirected to the primary IP address of the second router and sending the redirect packet to the host; and

when it is determined to send a redirect packet to the virtual IP address of the second router, composing a redirect packet indicating that packets to be sent to the specific network are to be redirected to the virtual IP address of the second router and sending the redirect packet to the host;

wherein the first router implements a virtual router protocol.

6. The first router as recited in claim 5, wherein the virtual router protocol is VRRP or HSRP.

7. A first router that supports a virtual router protocol, the first router being adapted for sending a redirect packet to a host, the redirect packet notifying the host that packets to be sent to a particular network are to be redirected to a second router, comprising:

a processor; and

a memory, at least one of the processor and the memory being adapted for;

determining whether to send a redirect packet to a primary IP address of the second router or to a virtual IP address of the second router, the virtual IP address being associated with one or more routers;

when it is determined to send a redirect packet to the primary IP address of the second router, composing a redirect packet indicating that packets to be sent to a specific network are to be redirected to the primary IP address of the second router and sending the redirect packet to the host; and

when it is determined to send a redirect packet to the virtual IP address of the second router, composing a redirect packet indicating that packets to be sent to the specific network are to be redirected to the virtual IP address of the second router and sending the redirect packet to the host;

wherein the redirect packet is an ICMP redirect.

8. A first router that supports a virtual router protocol, the first router being adapted for sending a redirect packet to a host, the redirect packet notifying the host that packets to be sent to a particular network are to be redirected to a second router, comprising:

a processor; and

a memory, at least one of the processor and the memory being adapted for;

determining whether to send a redirect packet to a primary IP address of the second router or to a virtual IP address of the second router, the virtual IP address being associated with one or more routers;

when it is determined to send a redirect packet to the primary IP address of the second router, composing a redirect packet indicating that packets to be sent to a specific network are to be redirected to the primary IP address of the second router and sending the redirect packet to the host; and

when it is determined to send a redirect packet to the virtual IP address of the second router, composing a redirect packet indicating that packets to be sent to the specific network are to be redirected to the virtual IP address of the second router and sending the redirect packet to the host;

wherein determining whether to send a redirect packet to a primary IP address of the second router or to a virtual IP address of the second router comprises;

determining whether a virtual router protocol is running on the first router.

9. The first router as recited in claim 8, wherein determining whether a virtual router protocol is running on the first router comprises:

receiving a packet; and

determining whether a virtual router protocol is running on an interface of the first router on which the packet was received.

10. The first router as recited in claim 9, wherein when it is determined that a virtual router protocol is not running on the interface of the first router on which the packet was received, it is determined to send a redirect packet to the primary IP address of the second router.

11. A first router that supports a virtual router protocol, the first router being adapted for sending a redirect packet to a host, the redirect packet notifying the host that packets to be sent to a particular network are to be redirected to a second router, comprising:

a processor; and

a memory, at least one of the processor and the memory being adapted for;

determining whether to send a redirect packet to a primary IP address of the second router or to a virtual IP address of the second router, the virtual IP address being associated with one or more routers;

when it is determined to send a redirect packet to the primary IP address of the second router, composing a redirect packet indicating that packets to be sent to a specific network are to be redirected to the primary IP address of the second router and sending the redirect packet to the host; and

when it is determined to send a redirect packet to the virtual IP address of the second router, composing a redirect packet indicating that packets to be sent to the specific network are to be redirected to the virtual IP address of the second router and sending the redirect packet to the host;

wherein determining whether to send a redirect packet to a primary IP address of the second router or to a virtual IP address of the second router comprises;

determining whether one or more HSRP groups are configured for the second router; and

when it is determined that no HSRP groups are configured for the second router, it is determined to send the redirect packet to the primary IP address of the second router.

12. A first router that supports a virtual router protocol, the first router being adapted for sending a redirect packet to a host, the redirect packet notifying the host that packets to be sent to a particular network are to be redirected to a second router, comprising:

a processor; and

a memory, at least one of the processor and the memory being adapted for;

determining whether to send a redirect packet to a primary IP address of the second router or to a virtual IP address of the second router, the virtual IP address being associated with one or more routers;

when it is determined to send a redirect packet to the primary IP address of the second router, composing a redirect packet indicating that packets to be sent to a specific network are to be redirected to the primary IP address of the second router and sending the redirect packet to the host; and

when it is determined to send a redirect packet to the virtual IP address of the second router, composing a redirect packet indicating that packets to be sent to the specific network are to be redirected to the virtual IP address of the second router and sending the redirect packet to the host;

wherein determining whether to send a redirect packet to a primary IP address of the second router or to a virtual IP address of the second router comprises;

performing a lookup in a virtual router table for the primary IP address of the second router;

determining from the virtual router table whether one or more HSRP groups are configured for the second router; and

when it is determined that no HSRP groups are configured for the second router, it is determined to send a redirect packet to the primary address of the second router.

13. A first router that supports a virtual router protocol, the first router being adapted for sending a redirect packet to a host, the redirect packet notifying the host that packets to be sent to a particular network are to be redirected to a second router, comprising:

a processor; and

a memory, at least one of the processor and the memory being adapted for;

determining whether to send a redirect packet to a primary IP address of the second router or to a virtual IP address of the second router, the virtual IP address being associated with one or more routers;

when it is determined to send a redirect packet to the primary IP address of the second router, composing a redirect packet indicating that packets to be sent to a specific network are to be redirected to the primary IP address of the second router and sending the redirect packet to the host; and

when it is determined to send a redirect packet to the virtual IP address of the second router, composing a redirect packet indicating that packets to be sent to the specific network are to be redirected to the virtual IP address of the second router and sending the redirect packet to the host;

wherein determining whether to send a redirect packet to a primary IP address of the second router or to a virtual IP address of the second router comprises;

performing a lookup in a virtual router table for the primary IP address of the second router; and

determining whether the second router is an active router for the virtual router protocol.

14. The first router as recited in claim 13, wherein when it is determined that the second router is an active router for the virtual router protocol, it is determined to send the redirect packet to a virtual address of the second router.

15. The first router as recited in claim 14, wherein composing a redirect packet when it is determined to send the redirect packet to a virtual address of the second router comprises:

obtaining one of one or more virtual IP addresses associated with the primary IP address of the second router; and

composing a redirect packet including the obtained virtual IP address associated with the primary IP address of the second router.

16. The first router as recited in claim 13, wherein when it is determined that the second router is not an active router for the virtual router protocol, it is determined that a redirect packet is not to be sent to the host.