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Configuration Guide - DCN and Server Management

CloudEngine 8800, 7800, 6800, and 5800 V200R003C00

This document describes the configurations of Trill, FCoE, DCB, and NLB Server Cluster Association.
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FIP Protocol

FIP Protocol


The FCoE Initialization Protocol (FIP) establishes and maintains FCoE virtual links between FCoE devices, for example, between ENodes and FC forwarders (FCFs).

An FCoE virtual link is established as follows:
  1. FIP discovers an FCoE VLAN and the FC virtual interface of the remote device.
  2. FIP completes initialization tasks such as fabric login (FLOGI) and fabric discovery (FDISC) for the FCoE virtual link.
After an FCoE virtual link is set up, FIP maintains the FCoE virtual link in the following way:
  • Periodically detects whether FC virtual interfaces at both ends of the FCoE virtual link are reachable.
  • Tears down the FCoE virtual link through Fabric logout (FLOGO).

FCoE Virtual Link Setup

Figure 2-16 shows the process of setting up an FCoE virtual link between an ENode and an FCF. The ENode and FCF exchange FIP frames to establish the FCoE virtual link. After the FCoE virtual link is set up, FCoE frames are transmitted on the link. FIP frames and FCoE frames have different Ethernet types and encapsulation modes. FCoE frame encapsulation is defined in the traditional FC protocol, whereas FIP frame encapsulation is not defined in the traditional FC protocol. In FIP implementation, an ENode initiates all protocol packets. An FCF initiates unsolicited FIP Advertisement packets, as described in FIP FCF discovery.

Figure 2-16 FCoE virtual link setup
Three phases are involved during the set up of an FCoE virtual link: FIP VLAN discovery, FIP FCF discovery, and FIP FLOGI and FDISC. The FIP FLOGI and FDISC processes are similar to the FLOGI and FDISC processes defined in the traditional FC protocol.
  1. FIP VLAN discovery

    FIP VLAN discovery discovers the FCoE VLANs that will transmit FCoE frames. In this phase, an ENode can discover all the potential FCoE VLANs but does not select an FCF.

    The FIP VLAN discovery process is as follows:
    1. An ENode sends a FIP VLAN discovery request to a multicast MAC address called ALL-FCF-MAC (01-10-18-01-00-02). All FCFs listen for packets destined for this MAC address.
    2. All FCFs that are reachable in a common VLAN of the ENode report one or more FCoE VLANs to the ENode. The FCoE VLANs are available for the ENode's VN_Port login.

    FIP VLAN discovery is an optional phase as defined in FC-BB-5. An FCoE VLAN can be manually configured by an administrator, or dynamically discovered using FIP VLAN discovery.

  2. FIP FCF discovery

    ENodes use FIP FCF discovery to locate FCFs that allow logins.

    The FIP FCF discovery process is as follows:
    1. Each FCF periodically sends Discovery Advertisement messages in each configured FCoE VLAN. The Advertisement messages are destined for the multicast MAC address ALL-ENode-MAC (01-10-18-01-00-01) on which all ENodes listen. The FIP FCF Discovery Advertisement message contains the FCF MAC address and FCoE virtual link parameters such as the FCF priority and timeout interval of FIP packets.
    2. The ENode obtains FCF information from the received Discovery Advertisement messages, selects an FCF with the highest priority, and sends a unicast Discovery Solicitation message to the selected FCF.
    3. After receiving the Discovery Solicitation message, the FCF sends a unicast Discovery Advertisement message, allowing the ENode to log in.

    FCFs send Discovery Advertisement messages periodically. However, it is inefficient for new ENodes joining a network to wait for Discovery Advertisement messages from all FCFs. Therefore, FC-BB-5 allows ENodes to send Discovery Solicitation messages to the multicast MAC address ALL-FCF-MAC. FCFs that receive the solicitation message send a unicast Discovery Advertisement message to the requesting ENode. Based on the received Discovery Advertisement messages, the ENode selects an FCF with the highest priority to set up a virtual link.


    After discovering all FCFs and selecting one for login, an ENode sends FIP FLOGI or FIP FDISC packets for establishing an FCoE virtual link with the VF_Port on the selected FCF. FCoE frames then can be exchanged on the established FCoE virtual link. FIP FLOGI and FIP FDISC packets are unicast packets and correspond to FLOGI and FDISC packets in FC respectively. FIP FLOGI and FIP FDISC packets are used for allocating MAC addresses to ENodes so that the ENodes can log in to the fabric.

    FIP FLOGI is similar to FIP FDISC. The difference is that FIP FLOGI refers to FCoE virtual ink setup when an ENode first logs in to the fabric, whereas FIP FDISC refers to FCoE virtual link setup for each VM when multiple VMs exist on an ENode. FIP FLOGI is used an example.

    The FIP FLOGI process is as follows:
    1. An ENode sends a FIP FLOGI Request to the FCF.
    2. The FCF responds to the FIP FLOGI Request of the ENode and allocates a locally unique MAC address, a Fabric Provided MAC Address (FPMA), to the ENode. Alternatively, the FCF responds to the FLOGI Request and permits the ENode to use its locally unique MAC address, the Server Provided MAC Address (SPMA).

FCoE MAC address

An ENode uses different source MAC addresses to encapsulate FIP and FCoE frames. A FIP frame uses a globally unique MAC address (ENode MAC address) assigned to a converged network adapter (CNA) during manufacturing, whereas an FCoE frame uses a locally unique MAC address (unique only within the local Ethernet subnet). The locally unique MAC address is dynamically assigned to an ENode by an FCF or specified on an ENode and acknowledged by an FCF. For details, see FIP FLOGI and FDISC.

The locally unique MAC address is called a fabric-provided MAC address (FPMA).

In Figure 2-17, an FPMA has an FC_ID and a 24-bit FCoE MAC Address Prefix (FC-MAP). FC-BB-5 defines 256 FC-MAPs to facilitate FCoE deployment. In most cases, the default FC-MAP value 0E-FC-00 can meet deployment requirements. If FC_IDs on an Ethernet VLAN are not unique, FC_IDs may overlap, for example, when different fabric or virtual storage area networks (VSANs) map to the same Ethernet VLAN. The use of different FC-MAPs solves this problem.

Map one FC fabric to the same Ethernet VLAN. If multiple FC fabrics run on the same Ethernet, map the FC fabrics to different VLANs.

Figure 2-17 FPMA format

FCoE Virtual Link Maintenance

FCoE virtual link monitoring

On a traditional FC network, FC can immediately detect faults on a physical link. In FCoE, FC cannot immediately detect faults on a physical link because of Ethernet encapsulation. FIP provides a Keepalive mechanism to solve this problem.

FCoE monitors an FCoE virtual link as follows:
  • An ENode periodically sends FIP Keepalive packets to an FCF. If the FCF does not receive FIP Keepalive packets within 2.5 times the keepalive interval, the FCF considers the FCoE virtual link faulty and terminates the FCoE virtual link.

  • An FCF periodically sends multicast Discovery Advertisement messages with the destination MAC address as ALL-ENode-MAC to all ENodes. If an ENode does not receive multicast Discovery Advertisement messages within 2.5 times the keepalive interval, the ENode considers the FCoE virtual link faulty and terminates the FCoE virtual link.


If an FCF does not receive FIP Keepalive packets from an ENode, the FCF sends a FIP Clear Virtual Link message, requesting FCoE virtual link teardown. If the ENode logs out, the ENode can send a Fabric Logout request to the FCF, requesting the FCF to delete the virtual link.

Updated: 2019-05-08

Document ID: EDOC1100004349

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