EXPEDITED FABRIC PATHS IN SWITCH FABRICS

1 . A switch fabric, comprising:

a set of network switches connected by a set of physical links;

an expedited fabric path comprising an additional physical link between two access switches in the set of network switches that is isolated from the set of physical links; and

a selection mechanism that selects a subset of network traffic for forwarding on the expedited fabric path based on an attribute of the network traffic.

2 . The switch fabric of claim 1 , wherein the selection mechanism comprises:

a network controller that provides, to at least one of the two access switches, a rule for forwarding the subset of network traffic on the expedited fabric path.

3 . The switch fabric of claim 2 , wherein the rule comprises at least one of:

a class of service;

a type of service;

a label;

a port;

an address;

a source;

a destination; and

a link aggregation group.

4 . The switch fabric of claim 1 , wherein:

the selection mechanism comprises a host connected to one of the two access switches, and

the attribute comprises:

a first segment encoded in a packet from the host to the access switch; and

a second segment encoded in the packet from the access switch to the expedited fabric path.

5 . The switch fabric of claim 4 , wherein:

the first segment comprises an Internet Protocol version 6 (IPv6) segment, and

the second segment comprises a Multiprotocol Label Switching (MPLS) segment.

6 . The switch fabric of claim 1 , further comprising:

a forwarding mechanism in at least one of the two access switches, wherein the forwarding mechanism is configured to forward the subset of network traffic from the application on the expedited fabric path when a parameter in the subset of network traffic matches the attribute.

7 . The switch fabric of claim 6 , wherein the forwarding mechanism is further configured to:

remove the parameter from packets in the subset of network traffic prior to forwarding the packets on the expedited fabric path.

8 . The switch fabric of claim 1 , wherein the expedited fabric path further comprises one or more expedited fabric path switches between the pair.

9 . The switch fabric of claim 1 , wherein the additional physical link connects a first access switch and a second access switch within a logical unit of a network.

10 . The switch fabric of claim 1 , wherein the additional physical link connects a first access switch in a first logical unit of a network and a second access switch in a second logical unit of the network.

11 . A method, comprising:

identifying network traffic for transmission between two access switches in a switch fabric;

selecting a subset of the network traffic for forwarding on an expedited fabric path comprising a physical link between the two access switches that is isolated from other physical links in the switch fabric; and

forwarding, by an access switch in the two access switches, the subset of the network traffic on the expedited fabric path.

12 . The method of claim 11 , further comprising:

forwarding a remainder of the network traffic on one or more of the other physical links in the switch fabric.

13 . The method of claim 11 , wherein selecting the subset of the network traffic for forwarding on the expedited fabric path comprises:

receiving, by the access switch from a network controller, a rule for forwarding the subset of network traffic on the expedited fabric path.

14 . The method of claim 13 , wherein the rule comprises at least one of:

a class of service;

a type of service;

a label;

a port;

an address;

a source;

a destination; and

a link aggregation group.

15 . The method of claim 11 , wherein selecting the subset of the network traffic for forwarding on the expedited fabric path comprises:

receiving, from a host connected to the access switch, a request to forward the subset of the network traffic from the host on the expedited fabric path.

16 . The method of claim 11 , wherein selecting the subset of the network traffic for forwarding on the expedited fabric path comprises:

matching, at the access switch, a parameter in the subset of the network traffic to an entry in a forwarding table for forwarding the subset of the network traffic on the expedited fabric path.

17 . The method of claim 11 , wherein selecting the subset of the network traffic for forwarding on the expedited fabric path comprises:

identifying, at the access switch, a parameter in the subset of the network traffic for forwarding the subset of the network traffic on the expedited fabric path; and

removing the parameter from packets in the subset of network traffic prior to forwarding the packets on the expedited fabric path.

18 . The method of claim 11 , wherein forwarding the subset of the network traffic on the expedited fabric path comprises:

placing a packet from the subset of the network traffic in a dedicated input queue for the expedited fabric path.

19 . An apparatus, comprising:

one or more processors; and

memory storing instructions that, when executed by the one or more processors, cause the apparatus to:

identify network traffic for transmission between two access switches in a switch fabric;

select a subset of the network traffic for forwarding on an expedited fabric path comprising a physical link between the two access switches that isolated from other physical links in the switch fabric; and

forward the subset of the network traffic on the expedited fabric path.

20 . The apparatus of claim 19 , wherein forwarding the subset of the network traffic on the expedited fabric path comprises:

placing a packet from the subset of the network traffic in a dedicated input queue for the expedited fabric path.