Re: [Isis-wg] WG Last Call for draft-ietf-isis-auto-conf-04

Hi Les, 

On 1/22/17, 12:57 PM, "Les Ginsberg (ginsberg)" <ginsberg@cisco.com> wrote:

>Acee -
>
>Thanx for reviewing the document.
>Responses inline.
>
>> -----Original Message-----
>> From: Isis-wg [mailto:isis-wg-bounces@ietf.org] On Behalf Of Acee Lindem
>> (acee)
>> Sent: Sunday, January 22, 2017 5:39 AM
>> To: Christian Hopps; isis-wg@ietf.org
>> Cc: draft-ietf-isis-auto-conf@ietf.org; isis-chairs@ietf.org;
>>isis-ads@ietf.org
>> Subject: Re: [Isis-wg] WG Last Call for draft-ietf-isis-auto-conf-04
>> 
>> Hi IS-IS WG,
>> 
>> I have reviewed the document and support publication. I have the
>>following
>> minor comments:
>> 
>>     1. It should be made clear that the A-Bit indicates that an IS-IS
>>router
>> supports auto-configuration and, is not, necessarily auto-configured
>>itself.
>> After reading the whole draft, I know that this is the definition of
>>the bit but
>> the initial text says the router is ³operating in auto-configuration
>>mode.²
>
>[Les:] It is clearly stated that the A flag does indeed mean
>
>" the router is operating in auto-configuration mode."
>
>I do not see any text which suggests otherwise.

But there is no prior definition of “auto-configuration mode”. I think
most readers would believe that this indicates that only routers
performing auto-configuration will form adjacencies. Yet the documents
states: 

   This document also defines mechanisms to prevent the unintentional
   interoperation of auto-configured routers with non-autoconfigured
   routers.  See Section 3.3.

Where is the interoperation? This definitely needs to be clarified - I
don’t see how the authors can argue on this point!

>
>???
>
>>     2. In the duplicate detection in section 3.4.3, could you note that
>>an IS-IS
>> router should be able to detect discern the case where two interfaces
>>on the
>> IS-IS router performing auto-configuration are connected to the same
>> network.
>> 
>[Les:] Multiple connections of the same system to the same network can
>occur in the absence of auto-configuration and detection of this case is
>not altered by auto-configuration. This is detected by receiving a hello
>with the same source MAC address as a local interface. There are then the
>following cases:
>
>1)Two interfaces on the local router are connected to the same media.
>This is further validated by having the same systemID. The means for
>detecting this as well as resolving this are not altered by
>auto-configuration.
>
>2)Two neighbors connected to the same network have the same source MAC
>address. This is distinguished by having different system IDs in the
>hellos. The means for detecting this as well as resolving this are not
>altered by auto-configuration.
>
>3)Two neighbors connected to the same network have the same source MAC
>address and the same systemID. This is distinguished by having different
>router fingerprint TLVs in the hellos - something only an auto-config
>router could do. But the additional detection capability does not provide
>any additional means to correct this issue.
>
>The authors discussed this point during the writing of the draft and
>decided specifically NOT to comment on this issue as it by nature is no
>different than what can occur without auto-config and there is no good
>way to automatically recover from this case i.e. clearly we cannot alter
>the physical connections by programmatic means - nor do we assume/require
>a programmatic capability of assigning MAC addresses.
> 
>So, I am not sure what we could say other than to note that this can
>occur - but non-auto-config implementations already have to detect this -
>so does it make sense to comment on this in the auto-config draft?

Given that consequences of this mis-wiring are more severe when IS-IS
auto-configuration is being used, I think this deserves at least the
discussion above included in the draft.

Thanks,
Acee 

>
>   Les
>
> 
>> Thanks,
>> Acee
>> 
>> On 1/17/17, 7:00 AM, "Isis-wg on behalf of Christian Hopps"
>> <isis-wg-bounces@ietf.org on behalf of chopps@chopps.org> wrote:
>> 
>> >
>> >Hi Folks,
>> >
>> >We are starting a WG Last Call for
>> >
>> >  "ISIS Auto-Configuration"
>> >  - https://datatracker.ietf.org/doc/draft-ietf-isis-auto-conf/
>> >
>> >The WGLC will expire in 2 weeks on Jan 31, 2017.
>> >
>> >Thanks,
>> >Chris & Hannes.
>> 
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