First we’ll configure FabricPath on all the layer-2 interfaces on N7K3 and N7K4.Ĭonfigure FabricPath switchports N7K3(config)# int e4/13-16 Nothing yet, so let’s bring up some interfaces and look again.
System ID SNPA Level State Hold Time Interface N7K6(config)# show fabricpath isis adjacencyįabricpath IS-IS domain: default Fabricpath IS-IS adjacency database: Notice we can already run this command to look at the IS-IS adjacencies, which will be used to build our MAC-in-MAC routing topology and shortest path tree. N7K6(config)# show fabricpath switch-id local N7K5(config)# show fabricpath switch-id local N7K4(config)# show fabricpath switch-id local N7K3(config)# show fabricpath switch-id local We can statically configure these so they’re easier to recognize in the FabricPath domain.Ĭonfigure Static FabricPath Switch-ID N7K3(config)# fabricpath switch-id 73 * 76 e8ed.f339.4e45 Primary Confirmed Yes NoĪs you can see, these SIDs are a little all over the place. * 104 e8ed.f339.4f45 Primary Confirmed No No * 327 e8ed.f339.4e44 Primary Confirmed No No * 370 e8ed.f339.4f44 Primary Confirmed No No SWITCH-ID SYSTEM-ID FLAGS STATE STATIC EMULATED/ The system-id is the MAC of the switch or VDC (verify with show vdc internal mac_address_table on the Admin VDC) N7K3# show fabricpath switch-id This is a 12-bit address dynamically assigned via DRAP (Dynamic Resource Allocation Protocol), which is used for identifying the switch in the FabricPath domain. Notice below that we are already assigned a SID (switch-ID). Notice the default configuration of FabricPath N7K3# show run fabricpathĪll we’ve done so far is enable the FabricPath feature-set. Notice this automatically allows the feature-set in the VDC vdc N7K3 id 4Įnable the FabricPath feature-set on the switches/VDCs N7K3# conf t
Install the feature-set in the Admin VDC ADMIN# conf tĪDMIN(config)# install feature-set fabricpath Our end-goal will look like this, with FabricPath running between the N7Ks, and Classical Ethernet running to the bottom two switches. Hello Time 2 sec Max Age 20 sec Forward Delay 15 secīridge ID Priority 24616 (priority 24576 sys-id-ext 40)īridge ID Priority 24626 (priority 24576 sys-id-ext 50) We’ll take a look at this again in a few minutes.
Before we dive into the configuration, let’s check out the current VLAN database and Spanning-Tree on N7K3. We will be using this topology for this walkthrough. When traffic comes into the FabricPath domain, a single lookup is performed to identify the switch closest to the destination, providing optimal flows. If there is a failure on one of the links, traffic will be redistributed across all the others. With FabricPath, we have the capability to actively forward on all links.
Oh, and did I mention no ability for equal-cost multipathing (ECMP)?!
What limitations? Some that come to mind are poor convergence, unnecessary flooding and maintenance of full CAM tables. Routing protocols for the win!įabricPath was designed to overcome the limitation of Spanning-Tree Protocol (STP). This is achieved by running IS-IS protocol in the L2 control plane, where it is responsible for building the topology and Shortest Path Tree (SPT). For those looking for details on FabricPath, here are some great resources that helped me along the way.īRKDCT-3313 – FabricPath Operation and Troubleshooting (2014)īRKDCT-2081 – Cisco FabricPath Technology and Design (2014)įabricPath is Layer 2 routing, also known as MAC-in-MAC routing. This post assumes you already have a basic understanding of FabricPath. For those just looking for a sample config, a full config is provided at the bottom of this post. I’ll also run through a configuration, observing behaviors along the way. In this blog post I’ll be looking at FabricPath, it’s purpose and how it pertains to the CCIE Data Center lab exam. It only makes sense that we connect with each other in the most immediate way, with all lines of communication open and inviting. We’re all cut from the same cloth, or in other words, fabric.