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packet fast forwarding

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  • 1.  packet fast forwarding

    Posted Jan 10, 2022 03:36 AM
    Hello All,

    How L3 switches in the world of HP is handling packet fast forwarding at the hardware level ? For sure high range  products are not switching packets with process switching. In other words, cisco have addressed this issue by designing CEF. How HPE have done it ? is there any standard or an RFC that is addressing packet fast forwarding on hardware level. Thank you.

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    otman ibrak
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  • 2.  RE: packet fast forwarding

    EMPLOYEE
    Posted Jan 10, 2022 04:00 AM
    Hi @oibrak!

    HPE Comware-based switches have fast forwarding feature:

    Fast forwarding reduces route lookup time and improves packet forwarding efficiency by using a high-speed cache and data-flow-based technology. It identifies a data flow by using the following fields: source IP address, source port number, destination IP address, destination port number, and protocol number. After a flow's first packet is forwarded through the routing table, fast forwarding creates an entry and uses the entry to forward subsequent packets of the flow.

    It can be tweaked a little bit, but no many options are available. More info you can find in an 'IP Services" Config guide for respective platform, for example here is such guide for HPE 5940 - https://support.hpe.com/hpesc/public/docDisplay?docLocale=en_US&docId=a00077572en_us , page 149.

    AOS and AOS-CX switches should have similar feature, but I am not so familiar with those devices.


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    Ivan Bondar
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    Original Message


  • 3.  RE: packet fast forwarding

    Posted Jan 10, 2022 04:13 AM
    Hello Ivan,

    thanks for your response ! I understand that Fast forwarding is the technique that emerged after process switching and it is based on caching the lookups result of a specific flow, If I may say it is based on flow pattern with source IP address, source port number, destination IP address, destination port number, and protocol number as key informations. What I would like to know is how HPE is handling packet forwarding on the hardware ? if they offer that on their products.

    thanks

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    otman ibrak
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    Original Message


  • 4.  RE: packet fast forwarding

    EMPLOYEE
    Posted Jan 10, 2022 06:04 AM
    On Aruba AOS-CX switches, there is currently only HW based forwarding after selected routes from RIB table are installed in FIB (ASIC).
    There are almost no CPU processed packet (very rarely for fragments for instance).
    Having first packet CPU routed and then programmed in HW is not something currently done; routed traffic is processed entirely by ASIC.

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    Vincent Giles
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    Original Message


  • 5.  RE: packet fast forwarding

    EMPLOYEE
    Posted Jan 10, 2022 06:08 AM
    Hi Otman,

    HPE is handling packets in hardware. The first packet from a flow is processed by CPU which on its turn creates a cache record in FIB. All subsequent packets from the same flow hit the cache record and forwarding happens solely in hardware (ASIC) and at line-rate speeds.


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    Ivan Bondar
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    Original Message