FCoE over trill

#The present disclosure relates generally to communication networks and, more particularly, to communication networks implementing multiple communication protocols.

#The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

#Ethernet is increasingly used as a common infrastructure for all types of traffic within data center networks. Accordingly, other communication protocols that are useful in data center networks are increasingly required to coexist with an Ethernet infrastructure. For example, the Fibre Channel over Ethernet (FCoE) protocol is used in some Ethernet-based data center networks to allow Fibre Channel (FC) devices (e.g., in storage area networks) to relay traffic over Ethernet. As another example, the Transparent Interconnection of Lots of Links (TRILL) protocol is used in some Ethernet-based data center networks to provide shortest-path bridging between source and destination nodes on the Ethernet. As an increasing number of protocols are merged into a common architecture, however, significant inefficiencies can arise.

#FIG. 1 is a block diagram of an example network device that implements packet processing techniques of the present disclosure, according to an embodiment.

#FIG. 2 is a flow diagram of an example method for processing packets in a network device, according to an embodiment.

#FIG. 3 is a block diagram of an example data center network that utilizes network devices, such as the example network device of FIG. 1, to implement FCoE and TRILL protocols within an Ethernet infrastructure, according to an embodiment.

#Various communication protocols, such as Ethernet, Fibre Channel over Ethernet (FCoE), and Transparent Interconnection of Lots of Links (TRILL), are commonly used in data center environments. FCoE allows Ethernet to carry traffic between native Fibre Channel (FC) devices, such as devices used in storage area networks, and/or FCoE end nodes (ENodes). An FCoE packet is formed by encapsulating an FC frame with an Ethernet header. The FC frame includes an FC destination identifier “D_ID” that indicates the intended recipient of the FC frame. Typically, an FCoE forwarder (FCF) device or FCoE data-plane forwarder (FDF) device updates source and destination media access control (MAC) addresses of the Ethernet header of the FCoE packet at each hop until the device corresponding to the FC destination identifier (or a native FC network including such a device) is reached. In particular, the source MAC address is changed to the MAC address of the FCF or FDF device forwarding the packet, and the destination MAC address is changed to the MAC address of either the destination indicated by the FC destination identifier, or the next FCF or FDF device on the hop path towards that destination. At each hop, the FCF or FDF device determines the destination MAC address for the next hop based on the FC destination identifier and a routing protocol called Fabric Shortest Path First (FSPF). Typically, each FCF or FDF device also enforces security policies between ENodes, in a process referred to as “zoning”. Under the current FCoE Standard, INCITS T11 FC-BB-5, each FCoE packet must be forwarded through at least one FCF device or FDF device.

#TRILL efficiently handles Ethernet traffic by providing shortest-path bridging over a TRILL cloud that includes TRILL routing bridge devices known as “RBridges”. The TRILL cloud is generally transparent to the rest of the network. When an Ethernet packet encounters the TRILL cloud, a first RBridge device serves as an “ingress RBridge”. Whereas FCoE encapsulates an FC frame in an Ethernet packet by adding Ethernet header information, the ingress RBridge device encapsulates each Ethernet packet by adding TRILL protocol header information. Specifically, the ingress RBridge device adds a “TRILL header” and a link transport header.

#The TRILL header includes a TRILL destination identifier known as an Egress RBridge Nickname. For a particular Ethernet packet received by the ingress RBridge device, the Egress RBridge Nickname indicates which RBridge device will serve as an “egress RBridge” device terminating the TRILL cloud. Generally, the ingress RBridge device will select as the egress RBridge device an RBridge device that is nearest to the intended destination of the Ethernet packet (as identified by the destination MAC address of the original Ethernet packet).