guide_c07-690079

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The spine in this design is also used to perform the routing function between the FabricPath cloud and the rest of the network. The default gateway for the servers is located in the spine layer, which, being also the router in the topology, performs the function of an edge in FabricPath. At the time of this writing, the Cisco Nexus 7000 Series hardware combination that provides this capability consists of F1 cards (spine function) together with the M1 cards (routing function). In the topology shown in Figure 13, the spine layer, which is also an aggregation layer since it aggregates multiple edge switches, operates simultaneously in two modes: ● It forwards Layer 2 traffic between the edge devices exclusively based on the destination switch-id, without the need to learn MAC addresses (east-to-west traffic). ● It also learns MAC addresses exclusively for the purpose of encapsulating routed traffic into FabricPath frames (north-to-south traffic). Figure 13. Layer 3 Aggregation/Spine These two behaviors are completely independent, in that even if, as a theoretical example, the 128-K adjacency table of the M1 card fully filled up, the E-W Layer 2 traffic would still be forwarded based on the switch-id and not flooded. Compared with a spanning-tree design or a vPC design, this design includes the following advantages: ● Ease of configuration ● Multipath forwarding for unicast and multicast Layer 2 and Layer 3 traffic ● Faster convergence times ● Loop mitigation thanks to the use of a Time to Live (TTL) field in FabricPath frames The focus of this section is on the design of this hybrid Layer 2/Layer 3 spine/aggregation layer. This is not the only possible design option. For instance, you can also add Layer 3 to an edge switch and use the spine as a pure Layer 2 spine, or connect a pair of Layer 2 edge switches to dedicated routing devices, as highlighted in Figure 14. It is outside of the scope for this document to discuss these specific design options further. © 2011-2012 Cisco and/or its affiliates. All rights reserved. This document is Cisco Public Information. Page 16 of 54
Figure 14. Fabricpath design with separate L3 edge Topology Considerations FabricPath technology allows building multiple logical topologies on the same physical topology. At the time of this writing, this functionality has not yet been enabled by the software, so you should not attempt to create additional topologies besides the default topology 0. Declaring VLANs as FabricPath VLANs All VLANs that are meant to be forwarded according to Cisco FabricPath rules must be created as FabricPath VLANs. A VLAN needs to be explicitly configured for Classic Ethernet (CE) mode or for FabricPath mode. By default, all VLANs are in CE mode. These CE VLANs are not brought up on FabricPath core links. They can be forwarded on the FabricPath edge ports locally or to other Classic Ethernet switches. The command required to configure a VLAN in FabricPath mode is: DC1-Agg1(config)# vlan 101 DC1-Agg1(config-vlan)# mode fabricpath © 2011-2012 Cisco and/or its affiliates. All rights reserved. This document is Cisco Public Information. Page 17 of 54
Page 1 and 2: Cisco FabricPath Design Guide: Usin
Page 3 and 4: Edge Cisco Nexus 5500 Switch (DC1-5
Page 5 and 6: ● Cisco Nexus Fabric Extenders (F
Page 7 and 8: The Layer 3 demarcation point can b
Page 9 and 10: Each device in the topology is iden
Page 11 and 12: 0/121/0, number of next-hops: 0 via
Page 13 and 14: Figure 10. Unicast load balancing i
Page 15: Multicast Forwarding Multicast traf
Page 19 and 20: If an M1 card is present in the sam
Page 21 and 22: MAC Scalability Considerations In a
Page 23 and 24: Notice that even if the total MAC c
Page 25 and 26: As a result of this configuration,
Page 27 and 28: Agg1: fabricpath domain default roo
Page 29 and 30: ● Consider using manually configu
Page 31 and 32: Direct Connectivity between Edge Sw
Page 33 and 34: In addition, even if the vPC+ peer-
Page 35 and 36: Figure 31. Traffic routing by M1 ca
Page 37 and 38: Figure 34. Impact of multiple links
Page 39 and 40: Sample Configurations This section
Page 41 and 42: priority 110 ip 10.30.0.1 interface
Page 43 and 44: fabricpath domain default root-prio
Page 45 and 46: interface port-channel2 description
Page 47 and 48: vrf context management ip route 0.0
Page 49 and 50: interface port-channel1 description
Page 51 and 52: no feature ssh cfs eth distribute f
Page 53: switchport mode fex-fabric fex asso

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