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Re: [Lsr] Flex Algorithms Drafts

Uma Chunduri <umac.ietf@gmail.com> Wed, 02 May 2018 03:38 UTC

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From: Uma Chunduri <umac.ietf@gmail.com>
Date: Tue, 01 May 2018 20:38:51 -0700
Message-ID: <CAF18ct7QqZ_G1wvxt46DnnN4Jh43jS5Hmwt5vrsid3-PvhX-hA@mail.gmail.com>
To: Peter Psenak <ppsenak@cisco.com>
Cc: Uma Chunduri <uma.chunduri@huawei.com>, "Acee Lindem (acee)" <acee@cisco.com>, "lsr@ietf.org" <lsr@ietf.org>, "draft-hegdeppsenak-isis-sr-flex-algo@ietf.org" <draft-hegdeppsenak-isis-sr-flex-algo@ietf.org>
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Subject: Re: [Lsr] Flex Algorithms Drafts
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Hi Peter,

Thanks for your response. See my questions below -

On Tue, Apr 17, 2018 at 2:31 AM, Peter Psenak <ppsenak@cisco.com> wrote:

> Hi Uma,
>
> please see inline:
>
>
> On 17/04/18 00:14 , Uma Chunduri wrote:
>
>> Dear All,
>> I am neutral to combining the content of OSPF and IS-IS into a single
>> draft.
>> However, I have 2 questions on this draft.
>> 1.
>>    0                   1                   2                   3
>>      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
>>     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>     |      Type     |    Length     |   Algorithm   |  Metric Type  |
>>     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>     |   Alg. Type   |    Priority   |
>>     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>     |                          Sub-TLVs                             |
>>     +                                                               +
>>     |                            ...                                |
>>     |                                                               |
>>     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>> */       Algorithm: Flex-Algorithm number.  Value between 128 and 255/*
>> */      inclusive./*
>> */      Algorithm Type: Single octet identifying the algorithm type used/*
>> */      to compute paths for the Flex-Algoritm.  Values are defined in/*
>> */      "IGP Algorithm Types" registry defined under "Interior Gateway/*
>> */      Protocol (IGP) Parameters" IANA registries./*
>> Why there are two fields "Algorithm" and "Algorithm Type" ?
>>
>
> these are being renamed in the next update to:
>
> Flex-Algorithm - Single octet value between 128 and 255 inclusive
>

1.
"Algorithm "  as defined in the draft -  I see is nothing but a light
weight sub topology (with out MT ADJs)  computed using an "Alg. Type".

As of now -

"Algorithm" type X is using "Alg.Type" Y to compute  routes?

After the change you mentioned, this would become


"Algorithm" type X is using "Alg.Type" Y to compute  routes?

IMO, Overloading of the terms cause lot of  confusion (and
mis-understanding) down the line. This happened already in a different
context for IS-IS; ask me how I will give clear example.

I followed the other thread and agree with some of the points raised by Jie
w.r.t what is being defined and what is being done.



>
> IGP Alg. Type - Single octet. Value between 0 and 127 inclusive, that
> identifies IGP algorithm type used to compute paths for the Flex-Algoritm.
> Values are defined in "IGP Algorithm Types" registry defined under
> "Interior Gateway Protocol (IGP) Parameters" IANA registries


> What are we saving here by overloading the terminology?

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