Date: Fri, 12 Mar 2010 00:44:58 -0800 From: Julian Elischer <julian@elischer.org> To: "Robert N. M. Watson" <rwatson@freebsd.org> Cc: svn-src-head@freebsd.org, Qing Li <qingli@freebsd.org>, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r205024 - head/sys/net Message-ID: <4B99FF0A.5080504@elischer.org> In-Reply-To: <4B99FE46.6090001@elischer.org> References: <201003111756.o2BHukJu042449@svn.freebsd.org> <alpine.BSF.2.00.1003112128020.97017@fledge.watson.org> <9ace436c1003111530s3bd0de9cq451671909fb6aa64@mail.gmail.com> <5ADB6F0D-11F1-4F9F-87A0-64F57063981E@freebsd.org> <9ace436c1003112352l3b2505ceq63d9c78954520497@mail.gmail.com> <A543276F-1982-4F12-B325-7277C2B42C92@freebsd.org> <9ace436c1003120011v3c627aadka2e57615ae01fe6f@mail.gmail.com> <8726950E-5110-4FE1-90BB-B4205D637764@freebsd.org> <9ace436c1003120030m39f518basc77c7cff40299008@mail.gmail.com> <DEE37FC3-0843-4121-A001-51AB80FE2B32@freebsd.org> <4B99FE46.6090001@elischer.org>
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Julian Elischer wrote: > Robert N. M. Watson wrote: >>>> >>>> Today, we support three link state values: >>>> >>>> 170 /* >>>> 171 * Values for if_link_state. >>>> 172 */ >>>> 173 #define LINK_STATE_UNKNOWN 0 /* link invalid/unknown */ >>>> 174 #define LINK_STATE_DOWN 1 /* link is down */ >>>> 175 #define LINK_STATE_UP 2 /* link is up */ >>>> >>>> I'm confused about Julian's proposal because it seems to me that we >>>> already know when a driver hasn't set or is unable to determine the >>>> link state: it will (should) be set to LINK_STATE_UNKNOWN by default. the question is whether there is any other meaning for this state. For example "I have not started up yet" >>>> >>>> So the only question we don't know the answer to, at run-time, is >>>> whether a driver may *ever* set the link state (i.e., it thinks it >>>> knows how to), and hence whether or not tools like dhclient should >>>> try to wait for that to happen. That is the problem that an >>>> interface capability would solve. >>>> >>>> For the purposes of ECMP, you just need to decide on your policy: >>>> map UNKNOWN to either UP or DOWN for your purposes. yes this is a good approach assuming that there is no other meaning. >>>> >>>> Robert
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