# US 2021/0243095 A1 · Routing network traffic

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- Number: US 2021/0243095 A1
- Document ID: US20210243095A1
- Status: Published application
- Kind: A1
- Application number: 17/239,361
- Filed: 2021-04-23
- Published: 2021-08-05
- Earliest claimed: 2017-05-09
- Assignees: Cisco Technology, Inc.
- Applicants: Cisco Technology, Inc.
- Inventors: Murtuza Attarwala; Lars Olof Stefan Olofsson; Himanshu Shah
- Web page: https://patentgrep.com/patent/US20210243095A1

## CPC

- H04L 47/2433: {Allocation of priorities to traffic types}
- H04L 43/08: Monitoring or testing based on specific metrics, e.g. QoS, energy consumption or environmental parameters
- H04L 45/123: {Evaluation of link metrics (techniques for monitoring network metrics H04L43/08)}
- H04L 45/124: {using a combination of metrics}
- H04L 45/125: based on throughput or bandwidth
- H04L 45/22: {Alternate routing}
- H04L 45/302: Route determination based on requested QoS
- H04L 45/306: {Route determination based on the nature of the carried application}
- H04L 61/4511: using domain name system [DNS]
- H04L 45/04: {Interdomain routing, e.g. hierarchical routing}
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

A method may include receiving a domain name system (DNS) query at a network device, where the DNS query may be associated with a traffic flow identified for rerouting through an alternative path utilizing an alternative network device instead of a default path. The method may also include rewriting the DNS query such that the DNS query is routed through the alternative network device along the alternative path and to a DNS server associated with the alternative path. The method may additionally include receiving a DNS response from the DNS server, where a resource identified in the DNS response may be based on the DNS query coming through the alternative network device.

## Claims

### Claim 1

A method, comprising:
determining multiple paths from an origin of a traffic flow to a destination, each of the multiple paths including a first network domain path and a second network domain path;
obtaining first performance scores for the first network domain paths and the second network domain paths;
combining, for each path of the determined multiple paths, a first performance score for the first network domain path and a second performance score for the second network domain path;
designating a path with the best combined performance score as a primary path;
routing traffic along the primary path; and
rerouting traffic, in response the combined score of the primary path falling below a threshold, from the primary path to a backup path.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
designating, after the combining and before the routing, a path other than the primary path as the backup path.

### Claim 3 (depends on 2)

The method of claim 2, wherein the designating comprises designating as the backup path a path with different initial edge network device than the primary path.

### Claim 4 (depends on 2)

The method of claim 2, wherein the rerouting traffic comprises rerouting traffic to the designated backup path.

### Claim 5 (depends on 1)

The method of claim 1, wherein the first network domain path is within an internal network domain, and the second network domain path is outside the internal network domain.

### Claim 6 (depends on 1)

The method of claim 1, wherein the first designating comprises:
identifying at least two paths of the determined multiple paths to have identical best combined performance scores; and
applying equal cost multiple path routing to identifying the primary path.

### Claim 7

At least one non-transitory computer readable medium storing instructions which when executed by at least one processor, cause the at least one processor to:
determine multiple paths from an origin of a traffic flow to a destination, each of the multiple paths including a first network domain path and a second network domain path;
obtain first performance scores for the first network domain paths and the second network domain paths;
combine, for each path of the determined multiple paths, a first performance score for the first network domain path and a second performance score for the second network domain path;
designate a path with the best combined performance score as a primary path;
route traffic along the primary path; and
reroute traffic, in response the combined score of the primary path falling below a threshold, from the primary path to a backup path.

### Claim 8 (depends on 7)

The at least one non-transitory computer readable medium of claim 7, further comprising instructions which when executed by the at least one processor, cause the at least one processor to:
designate, after the combining and before the routing, a path other than the primary path as the backup path.

### Claim 9 (depends on 8)

The at least one non-transitory computer readable medium of claim 8, instructions which when executed by the at least one processor, cause the at least one processor to: designate as the backup path a path with different initial edge network device than the primary path.

### Claim 10 (depends on 8)

The at least one non-transitory computer readable medium of claim 8, wherein the reroute traffic comprises reroute traffic to the designated backup path.

### Claim 11 (depends on 7)

The at least one non-transitory computer readable medium of claim 7, wherein the first network domain path is within an internal network domain, and the second network domain path is outside the internal network domain.

### Claim 12 (depends on 7)

The at least one non-transitory computer readable medium of claim 7, instructions which when executed by the at least one processor, cause the at least one processor to:
identify at least two paths of the determined multiple paths to have identical best combined performance scores; and
apply equal cost multiple path routing to identifying the primary path.

### Claim 13

A system, comprising:
at least one processor;
a non-transitory computer readable medium storing instructions which when executed by the at least one processor causes the at least one processor:
determine multiple paths from an origin of a traffic flow to a destination, each of the multiple paths including a first network domain path and a second network domain path;
obtain first performance scores for the first network domain paths and the second network domain paths;
combine, for each path of the determined multiple paths, a first performance score for the first network domain path and a second performance score for the second network domain path;
designate a path with the best combined performance score as a primary path;
route traffic along the primary path; and
reroute traffic, in response the combined score of the primary path falling below a threshold, from the primary path to a backup path.

### Claim 14 (depends on 13)

The system of claim 13, further comprising instructions which when executed by the at least one processor, cause the at least one processor to:
designate, after the combining and before the routing, a path other than the primary path as the backup path.

### Claim 15 (depends on 14)

The system of claim 14, further comprising instructions which when executed by the at least one processor, cause the at least one processor to:
designate as the backup path a path with different initial edge network device than the primary path.

### Claim 16 (depends on 14)

The system of claim 14, wherein the reroute traffic comprises reroute traffic to the designated backup path.

### Claim 17 (depends on 13)

The system of claim 13, wherein the first network domain path is within an internal network domain, and the second network domain path is outside the internal network domain.

### Claim 18 (depends on 13)

The system of claim 13, further comprising instructions which when executed by the at least one processor, cause the at least one processor to:
identify at least two paths of the determined multiple paths to have identical best combined performance scores; and
apply equal cost multiple path routing to identifying the primary path.