Difference between LLT and GAB - Veritas Cluster Server

This is a discussion on Difference between LLT and GAB - Veritas Cluster Server ; Hello All, Can somebody please explan the different between the function of LLT and GAB. In my understanding, LLT is taking care of the heartbeat communication, then why GAB is required. Please explan. Thanks Biju .....

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Thread: Difference between LLT and GAB

  1. Difference between LLT and GAB


    Hello All,

    Can somebody please explan the different between the function of LLT and
    GAB. In my understanding, LLT is taking care of the heartbeat communication,
    then why GAB is required. Please explan.

    Thanks
    Biju ..

  2. Re: Difference between LLT and GAB

    compare LLT/GAB to TCP/IP


    So, what is the purpose of TCP ?
    It "carries" the data (the IP) around. The IP actually contains the
    data, but the TCP provides the connection.

    LLT (Low Latency Transport) carries the data around. As part of this
    "carry" process, it needs to connect, and while you're connecting, you
    might as well find out if the other side is alive (well, that is called
    a heartbeat).

    GAB (Global membership service and Atomic Broadcast) is the information
    that is sent around. This makes sure that all the nodes in the cluster
    knows what the state of the cluster is, the configuration, etc.

    Biju K Joseph wrote:
    > Hello All,
    >
    > Can somebody please explan the different between the function of LLT and
    > GAB. In my understanding, LLT is taking care of the heartbeat communication,
    > then why GAB is required. Please explan.
    >
    > Thanks
    > Biju ..


  3. Re: Difference between LLT and GAB


    GAB works b/w the LLT and HAD(VCS engine). The GAB uses specified
    interfaces on llttab using LLT ARP for cluster communications.


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  4. Re: Difference between LLT and GAB

    LLT is actually a Veritas developed protocol sitting on the DataLink
    layer of the ISO model, while ARP (part of the IP stack) sits between
    datalink and network layers. LLT does "talk" from MAC address to MAC
    address.

    Like TCP, you can have different ports (known TCP ports include 80 for
    http protocol, 21 for FTP ,etc..) GAB ports are numbered and used for:

    a : gab to gab communications between nodes in a cluster
    b : io fencing
    d : Oracle to Oracle communications ina RAC cluster
    f : fsckd (part of Veritas Cluster File system)
    h : HAD (the main VCS engine)
    o: ODM (Oracle Disk Manager) part of RAC
    q : qlockd (part of Veritas Cluster filesystem)
    u : used as an exclusive port in establishing Cluster Volume Manager members
    v: vxconfigd used in Cluster Volume Manager
    w: used in kernel-to-kernel communication for Cluster Volume Manager

    As mentioned before, LLT is just the transport.

    LLT (or actually the LLT Multiplexor or LMX) is used in Oracle RAC
    "cache fusion". LLT provides a fast transport for Oracle to use for this
    communication (if you link the Veritas Library in)

    bostonthunder777 wrote:
    > GAB works b/w the LLT and HAD(VCS engine). The GAB uses specified
    > interfaces on llttab using LLT ARP for cluster communications.
    >
    >


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