Our normal pattern for forwarding plane entities is create/modify/delete, the TAP v1 API fit nicely with that. The desire is to support changing the interface after it's created without deleting and re-creating to avoid as much potential traffic disruption as possible. An example is MTU (which neither v1 or v2 support). The desired maximum MTU may not be known at creation time or may change depending on routing so a modify capability seems appropriate. So be specific on your questions, want to control MTU and admin/link enable/disable, would like to know link status without polling.
DPDK TAP PMD (and vHost PMD) provide the same APIs as physical devices using the rte_eth_dev_*() functions allowing the next layer of code to very similar for physical and virtual devices. DPDK TAP PMD supports MTU, jumbo frames, extended statistics, link status change notifications, plus likely other features. These seem to me to be an advantage and not a drawback. I'm curious about the drawbacks mentioned and advantages of the VPP implementation, could you provide a more detail? More information will certainly help! Ken Coulson From: Damjan Marion <[email protected]> Date: Tuesday, November 6, 2018 at 9:36 AM To: "Coulson, Ken" <[email protected]> Cc: "[email protected]" <[email protected]> Subject: Re: [**EXTERNAL**] [vpp-dev] TAP v1/v2 API questions On 6 Nov 2018, at 18:19, Coulson, Ken <[email protected]<mailto:[email protected]>> wrote: I didn’t hear anything back on questions below so re-posting again for another attempt at answers. Ken Coulson From: <[email protected]<mailto:[email protected]>> on behalf of "Coulson, Ken" <[email protected]<mailto:[email protected]>> Date: Wednesday, October 31, 2018 at 11:10 AM To: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> Subject: [**EXTERNAL**] [vpp-dev] TAP v1/v2 API questions Per emails on this list tap v1 is being deprecated. tap v1 create/modify/delete and tap v2 is different in that it only has create/delete. Some questions: Is the intent to create a tap v2 modify API and/or to add capabilities to set interface API? What exactly would you like to modify? What capabilities? tap APIs presently have no MTU setting. Is there any plan to add that capability? Isn't there generic API for that? Is there any plan to use DPDK tap PMD? I don't see any benefits and I see several drawbacks of doing that. Why do you ask?
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