BROCADE IP PRIMER

Introduction802.1Qbb: Priority-based Flow Control (PFC)Establishes eight priorities for flow control based on the priority code pointfield in the IEEE 802.1Q tags to control individual data flows on shared losslesslinks. PFC capability allows FC storage traffic encapsulated in FCoEframes to receive lossless service from a link that is shared with traditionalLAN traffic, which is loss-tolerant.802.1Qaz: Enhanced Transmission Selection (ETS)ETS provides the capability to group each type of data flow, such as storage ornetworking, and assigns a group identification number to each of the groups,which are also called traffic class groups. And why should we care about that?Well, it means that you can manage bandwidth on the Ethernet link by allocatingportions (percentages) of the available bandwidth to each of the groups.Bandwidth allocation allows traffic from the different groups to receive theirtarget service rate (e.g., 8 Gbps for storage and 2 Gbps for LAN). Bandwidthallocation provides quality of service to applications.Incorporates Data Center Bridging Exchange (DCBX), a discovery and initializationprotocol that discovers the resources connected to the DCB cloud andestablishes cloud limits. DCBX distributes the local configuration and detectsthe misconfiguration of ETS and PFC between peers. It also provides the capabilityfor configuring a remote peer with PFC, ETS, and application parameters.The application parameter is used for informing the end node which priority touse for a given application type (e.g., FCoE, iSCSI). DCBX leverages the capabilitiesof IEEE 802.1AB Link Layer Discovery Protocol (LLDP).802.1Qau: Congestion Notification (QCN)An end-to-end congestion management that enables throttling of traffic at theedge nodes of the network in the event of traffic congestion.IETF - TRILLInternet Engineering Task Force (IETF) is developing a new shortest path framerouting for multi-hop environments. The new protocol is called TransparentInterconnection of Lots of Links, or TRILL for short, and is expected to be completedin the second half of 2010.• TRILL provides a Layer 2 (L2) multi-path alternative to the single path andnetwork bandwidth limiting Spanning Tree Protocol (STP), currentlydeployed in data center networks.• TRILL will also deliver L2 multi-hop routing capabilities, which are essentialfor expanding the deployment of DCB/FCoE solutions beyond accesslayer server I/O consolidation and into larger data center networks.Brocade IP Primer 77