Re: [mif] Five additional problem statements for mif----Different metric measurements

Hi,

On 2009-3-17, at 20:52, Min Hui wrote:
> This is the third one: Different metric measurements
>
> Metrics are used to measure the performance of routings, the lower
> metric it owns, the higher priority it has. For example, the default
> gateway is chosen based on the metric rule as RFC1122 description, The
> one have the lowest metric value becomes to the default gateway among
> several connected gateways, and the interface correspond to this
> gateway turns to be the default interface.

RFC1122 Section 3.3.4.3 only talks very broefly about using  
"preference" as a tie breaker and doesn't talk about metrics. Did you  
mean to point to a different RFC?

> Metric rules are different depending on the access technology and
> routing protocol, if the multiple interfaces connect to multiple
> access networks which have different measurements of metrics, the
> comparing of metrics will be meaningless. However, the current
> operating system really does this to choose routing among several
> different networks in multiple interfaces situation. For example,
> current metric rules define the 100M bps Ethernet network card to be
> 20 and 10M bps to be 30, but the CDMA data card set its metric value
> as 1, although its speed is lower than 100M bps Ethernet network card,
> and the host will choose the CDMA data card as the default network
> card. This problem confuses the selection of routing in multiple
> interfaces situation.

See above - I don't think what you describe is actually defined in  
RFC1122 (or at least, I can't find it there). Is this something that  
we have an RFC about, or is this something you have observed in some  
stack implementations?

Thanks,
Lars

>
> - Hui Min
>
> 2009/3/18 Min Hui <huimin.cmcc@gmail.com>:
>> Hi, all mif fans
>>
>> I have viewed the agenda of mif bof, and I notice some problem
>> statements for mif are not concluded in the current ps documents  
>> which
>> will be discussed in the meeting.
>> So I post these additional problems in the mail list for discussion,
>> all of them come from the draft
>> "draft-hui-ip-multiple-connections-ps-02" with some modifications
>> according to the comments received recently.
>> There are five problems in addition, which will be proposed in five
>> separated mails in order to have sufficient discussion for each of
>> them.
>> Five mails will be sent out following this mail, the structure is:
>> 1. Host routing
>> 2. DNS selection
>> 3. Different metric measurements
>> 4. Source address selection for IPv4
>> 5. TOS consideration
>>
>> Any comment is welcomed, and thanks for your notice.
>>
>> BR,
>> - Hui Min
>>
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Re: [mif] Five additional problem statements for mif----Different metric measurements

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