Using Fabric Port-Channels to Scale IP Connectivity to Hosts in Directly Connected Subnets in Massive Scale Data Centers

• US 20140064270A1
• Filed: 08/30/2012
• Published: 03/06/2014
• Est. Priority Date: 08/30/2012
• Status: Abandoned Application

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Kapadia, Shyam, Shah, Nilesh, Kanekar, Bhushan Mangesh
• Application Number:
  US13/599,446
• Publication Number:
  US 20140064270A1
• Time in Patent Office: Days
• US Class Current: 370/389
• CPC Class Codes: H04L 12/4675 Dynamic sharing of VLAN information amongst network nodes configuration of the network or of network elements H04L41/08
• CPC Class Codes: H04L 49/354 for supporting virtual local area networks [VLAN]

Abstract

Systems and methods are provided for using fabric port-channels for Switched Virtual Interfaces (SVIs) to scale IP connectivity for hosts in directly connected subnets in massive scale data centers. By representing SVIs by internal fabric port-channels, ToRs hosting the SVI can share routed traffic directed toward hosts within the associated vlan in a load-balanced manner without frequent updates to the FIB/Adjacency tables.

Claims

1. A method for IP scaling comprising:

installing a single subnet entry corresponding to a remote SVI/vlan in a FIB table for each of a plurality of non-local ToRs;

installing a plurality of server IP address entries corresponding to a plurality of hosts in a local vlan in a FIB table for each of one or more local ToRs;

programming ToR membership information for one or more SVI/vlans into a fabric hardware table;

receiving a packet on a first ToR in a first vlan, wherein the packet is directed to a host in a second vlan for which the first ToR is non-local;

performing a lookup for a destination index associated with an internal fabric port-channel that represents an egress ToR;

directing the packet from a switch fabric to a selected ToR out of the local ToRs;

performing a lookup for the destination server at the selected ToR;

determining whether an ARP entry for the destination server has been resolved; and

installing the destination server IP address entry in a FIB table if the ARP entry has been resolved.

2. The method of claim 1, wherein selection of the selected ToR out of the local ToRs is the result of a generated hash function.

3. The method of claim 1, wherein ToR membership information comprises a set of candidate next-hops to be installed on all non-local ToRs whose FIB entry has a subnet entry for the vlan associated with the ToR.

4. The method of claim 1, further comprising determining whether a final port of exit is local or non-local.

5. The method of claim 4, further comprising rewriting and transmitting the packet out of a local port if the final port of exit is determined to be local.

6. The method of claim 1, further comprising:

hitting a glean subnet prefix entry if the ARP entry has not been resolved;

triggering an ARP request to retrieve a MAC address for a corresponding destination IP address; and

installing the corresponding destination IP address on all local ToRs.

7. The method of claim 4, further comprising rewriting and transmitting the packet out to a ToR that has the destination as a directly-connected-host if the final port of exit is determined to be non-local.

8. The method of claim 1 further comprising:

detecting that a ToR leaves or enters membership of a certain vlan; and

updating the fabric hardware table with updated membership information.

9. A method for IPv4 scaling comprising:

representing a plurality of SVIs with a plurality of corresponding internal fabric port-channels;

receiving a packet at a first SVI destined for a host in a second SVI;

hitting a subnet entry in a FIB table corresponding to a destination index, wherein the destination index is associated with an internal fabric port-channel that represents an egress SVI interface; and

directing the packet to the egress SVI interface.

10. The method of claim 9, further comprising:

generating a hash function for selection of candidate ToRs at the switch fabric.

11. The method of claim 10, further comprising employing the generated hash function to select one of the candidate ToRs.

12. The method of claim 11, wherein generated hash function is based at least in part on a SMAC field contained in the packet.

13. The method of claim 9 wherein the subnet entry indicates rewrites to be made to the packet.

14. The method of claim 13, further comprising:

triggering an ARP request to retrieve a MAC address for a corresponding destination IP address; and

installing the corresponding destination IP address on all local ToRs.

15. The method of claim 13, further comprising:

determining whether the egress SVI interface is local or non-local.

16. A method comprising:

representing each of a plurality of internal port channels by a unique index;

detecting a packet directed to a first unique index; and

selecting a first ToR out of one or more candidate ToRs associated with a first SVI, wherein the SVI is identified by the first unique index.

17. The method of claim 16, further comprising:

generating a hash function for use in the selection of the first ToR, wherein the hash function is based on one or more fields within a received packet.

18. The method of claim 17, wherein the hash function is generated at a forwarding engine.

19. The method of claim 18, further comprising adding the hash function to the received packet.

20. The method of claim 17, further comprising generating the hash function at a switch fabric upon detecting the packet heading to a first internal port channel.