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Cisco FabricPath: Is It Switching, Routing Or A Bit Of Both?


Selecting Cisco FabricPath

Cisco FabricPath Protocol is a novelty in Cisco Software that is particularly created to provide a substitute for Spanning Tree Protocol (STP). As current switching technologies are unable to fulfill requirements of organizations, because of their limited forwarding process, Cisco FabricPath provides you with a better option with more flexibility. This technology utilizes System-to-Intermediate System (IS-IS) routing protocol in the control plane structure. You can easily use FabricPath instead spanning Tree Protocol (STP). STPs can help to prevent loops and floods at Layer 2.

However, they are not capable of performing active forwarding topology functions. Therefore, you can use FabricPath for active forwarding topology and prevent loops at layer 2 simultaneously. One of the major benefits that Cisco FabricPath offers is a loop-free environment with increased flexibility. This is the reason why business organizations consider Cisco FabricPath as a better substitute for STP.

Cisco FabricPath

You can also use Cisco FabricPath for routing your data and balance traffic across different data centers. Cisco FabricPath performs the layer 2 switching along with layer 3 routing functions that STP fails to perform. Cisco FabricPath uses the Ethernet as an underlying control protocol. It is built to provide the advantages of routing protocols and Layer 2 Network Ethernet infrastructure and uses the Equal Cost Multi-pathing network routing strategy. Through a Cisco certification, you will find FabricPath easy to operate, versatile, quick and easy to operate.

Cisco FabricPath’s architecture is MAC-in-MAC based and routed over to the destination FabricPath switch. Every device in a Cisco FabricPath environment has a unique Switch ID that is individually given or assigned through DRAP Protocol.

As organizations opt for architectures which are controller-centered, the demand for personnel that can manage core networks is increasing. This demand can be fulfilled via the CCNA Routing and Switching, which verifies your capabilities of operating and installing the updated software.

By using Cisco FabricPath, you can benefit in the following ways:

  1. If you obtain a Cisco certification, you can perform configuration in FabricPath that is easy and less time-consuming. However, tuning is recommended.
  2. You can boost data transfer capacity though Equal-cost multi-path routing (ECMP)strategy.
  3. You can get adaptability of design as well as error lenience.
  4. With Cisco FabricPath, you do not require STP. Each switch has its individual Layer 2 topology.
  5. Cisco FabricPath operates by default based on Conversational MAC address learning. This provides you with the option of selective learning of the MAC addresses of only the interested hosts instead of each and every MAC address within the domain.
  6. Cisco FabricPath provides you with loop avoidance and Equal-cost multi-path routing (ECMP) through the usage of Time To Live (TTL) field.

Cisco FabricPath utilizes System-to-Intermediate System (IS-IS) protocol to generate the most direct and shortest route to every Switch ID centered to link metrics/path rate, a total of 16 routes of ECMP Equal Cost Multi-pathing (ECMP)can be connected.

Layer 2 IS-IS Protocol

Layer 2 IS-IS protocol is different from the Layer 3 IS-IS protocol. Layer 2 IS-IS protocol does not need configuration as such. However, you will have to activate the Cisco FabricPath, and this will enable the IS-IS to function in the background by default.

This can enable you to get a constantly similar overview of the topology for each device all across the system of Cisco FabricPath. Also, every switch is provided with several active routes to each other switch. Not only that, but through the Layer 2 IS-IS protocol, you can also manage the traffic for balancing of data load utilizing Equal Cost Multi-pathing (ECMP).

The Cisco FabricPath Header

As a frame travels into the CiscoFabricPath field, an individual and new Cisco FabricPath header are assigned at the anterior of the frame. The new MAC address portion is termed as Inside MAC (iMAC). However, the Cisco FabricPath header included at the anterior is termed as the Outside MAC (OMAC).

This OMAC comprises of three different components; namely, the Outer Source Address (OSA), the Outer Destination Address (ODA) and lastly, the Forwarding Tag (FTag). The Ftag constitutes of the ether type andTime To Live(TTL) fields. The OSA and ODA, being the Cisco FabricPath source addresses as well as the destination, act as the Switch IDs in the CiscoFabricPath field. The switch ID then is employed for destination switches. The FTag is utilized for forwarding traffic within the Cisco FabricPath field. The FTag is utilized for Broadcast, Multicast as well as Unicast that is unknown. But, ODA is utilized only for Unicast which is known.

Similar to Ethernet, Cisco FabricPath has a header and functions in both Data as well as Control planes.

The Functioning of the Cisco FabricPath

Upon Layer 2, you can utilize the Cisco FabricPath protocol for multiple-path networking. The Cisco FabricPath header eliminates the requirement of running STP. It also averts any loops or storms. The Cisco FabricPathheader, in a FabricPath network, is linked to the ingress interface of the Cisco FabricPath field. Also, it is detached upon the egress interface of the Cisco Fabricpath domain.

Usually, Cisco FabricPath operates on Core and Aggregation switches rather than Access switches. Therefore, you can find Classical Ethernet switches upon the Access network topology operating along with the Cisco FabricPath field on the Aggregation or Core network topology.

You will observe that a Cisco FabricPath switch could either be a Core switch (spine switch) or an Edge switch (leaf switch). The Edge switch will have two ports; one being an edge port while the other functioning as the core port. They are linked to Cisco FabricPath networks as well as Classical Ethernet. But, the Core switch will have all its ports as core Cisco FabricPathports.

FabricPath VLANs

Switches automatically consist of Classical Etheral VLANs. However, for Cisco FabricPath, you must do the configuration of Cisco FabricPath VLANs. You will also need to alter the port mode into Cisco FabricPath mode. This is due to the fact that only FabricPath VLANs are capable of utilizing Cisco FabricPath ports.

Conversational MAC Learning

In the Cisco FabricPath, switching of traffic is carried out centered upon Conversational MAC learning. Unlike regular MAC learning, that is source based, Conversational MAC Learning only works by learning addresses of MAC only for interested hosts. In this way, a Cisco FabricPath switch is required to learn less MAC addresses. This decreases the size of the CAM table, resulting in the reduction of the need for memory and gaining scalability. In Conversational MAC learning, learning of the MAC table finishes after the interaction occurs in three directions.

Final Word

Since most of the switching technologies fail to meet the changing needs of business organizations due to their limited forwarding capacities, Cisco FabricPath is a more versatile and flexible option that can perform the Layer 2 switching and Layer 3 routing functions more effectively.


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