Re: [lisp] Review 6833bis-08 - General and NMR

[Dino Farinacci]

I will post at noon GMT if there are no objections.

Dino

> On Mar 21, 2018, at 12:52 AM, Victor Moreno (vimoreno)  
> wrote:
> 
> I think the new text is much better, unambiguous and addresses all concerns.
> 
> Thanks Dino,
> 
> -v
> 
>> On Mar 21, 2018, at 12:29 AM, Dino Farinacci  wrote:
>> 
>>> Could I not do the above even if the EID-prefix DID NOT EXIST? Or are we 
>>> restricting any application of policy only to LISP EID-prefixes, and not to 
>>> non-LISP prefixes? 
>> 
>> No, it would be either.
>> 
>>> The map-replies suggested in the new text would effectively be NMRs, 
>>> correct? i.e. Map-replies with empty locator sets and the ACT bits set.
>> 
>> The definition of a Negative Map-Reply is one with a empty RLOC-set. I will 
>> make that more clear in the definition and the description on how to return 
>> different actions.
>> 
>>> If that is the intent, maybe we need to revise the definitions for NMR and 
>>> ACT as I think right now there is some inconsistency/contradiction:
>>> 
>>> a) NMR definition - Issued in response to queries only for EIDs that DO NOT 
>>> EXIST
>>> b) ACT bits specification - for use in NMRs ONLY
>>> c) New text describing how the ACT bits are used to specify forwarding 
>>> behavior for EIDs that DO EXIST
>> 
>> Agree 100%. See new diff file.
>> 
>>> So NMRs are exclusive to non-existent or non-registered EIDs (a) and ACT 
>>> bits are exclusive to NMRs (b). Yet (c) implies that NMRs will be used for 
>>> EIDs that DO EXIST. So (c) contradicts (a).
>> 
>> No, not really. “Exist” is too general a term. We should say “not 
>> registered”. 
>> 
>> Let me know if new text is better.
>> 
>> Thanks,
>> Dino
>> 
>> 
> 

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Re: [lisp] Review 6833bis-08 - General and NMR

[Victor Moreno (vimoreno)]

I think the new text is much better, unambiguous and addresses all concerns.

Thanks Dino,

-v

> On Mar 21, 2018, at 12:29 AM, Dino Farinacci  wrote:
> 
>> Could I not do the above even if the EID-prefix DID NOT EXIST? Or are we 
>> restricting any application of policy only to LISP EID-prefixes, and not to 
>> non-LISP prefixes? 
> 
> No, it would be either.
> 
>> The map-replies suggested in the new text would effectively be NMRs, 
>> correct? i.e. Map-replies with empty locator sets and the ACT bits set.
> 
> The definition of a Negative Map-Reply is one with a empty RLOC-set. I will 
> make that more clear in the definition and the description on how to return 
> different actions.
> 
>> If that is the intent, maybe we need to revise the definitions for NMR and 
>> ACT as I think right now there is some inconsistency/contradiction:
>> 
>> a) NMR definition - Issued in response to queries only for EIDs that DO NOT 
>> EXIST
>> b) ACT bits specification - for use in NMRs ONLY
>> c) New text describing how the ACT bits are used to specify forwarding 
>> behavior for EIDs that DO EXIST
> 
> Agree 100%. See new diff file.
> 
>> So NMRs are exclusive to non-existent or non-registered EIDs (a) and ACT 
>> bits are exclusive to NMRs (b). Yet (c) implies that NMRs will be used for 
>> EIDs that DO EXIST. So (c) contradicts (a).
> 
> No, not really. “Exist” is too general a term. We should say “not 
> registered”. 
> 
> Let me know if new text is better.
> 
> Thanks,
> Dino
> 
> 

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Re: [lisp] Review 6833bis-08 - General and NMR

[Dino Farinacci]

> Could I not do the above even if the EID-prefix DID NOT EXIST? Or are we 
> restricting any application of policy only to LISP EID-prefixes, and not to 
> non-LISP prefixes? 

No, it would be either.

> The map-replies suggested in the new text would effectively be NMRs, correct? 
> i.e. Map-replies with empty locator sets and the ACT bits set.

The definition of a Negative Map-Reply is one with a empty RLOC-set. I will 
make that more clear in the definition and the description on how to return 
different actions.

> If that is the intent, maybe we need to revise the definitions for NMR and 
> ACT as I think right now there is some inconsistency/contradiction:
> 
> a) NMR definition - Issued in response to queries only for EIDs that DO NOT 
> EXIST
> b) ACT bits specification - for use in NMRs ONLY
> c) New text describing how the ACT bits are used to specify forwarding 
> behavior for EIDs that DO EXIST

Agree 100%. See new diff file.

> So NMRs are exclusive to non-existent or non-registered EIDs (a) and ACT bits 
> are exclusive to NMRs (b). Yet (c) implies that NMRs will be used for EIDs 
> that DO EXIST. So (c) contradicts (a).

No, not really. “Exist” is too general a term. We should say “not registered”. 

Let me know if new text is better.

Thanks,
Dino

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Re: [lisp] Review 6833bis-08 - General and NMR

[Victor Moreno (vimoreno)]

Thanks Dino,

I want to make sure I understand correctly. A couple of questions:


If the EID-prefix exists and there is a policy in the Map-Server to

have the requestor drop packets for the matching EID-prefix, 
then a

Drop/Policy-Denied action is returned. If the EID-prefix exists 
and

there is a authentication failure, then a Drop/Authentication-
failure action is returned. If either of these actions 
result as a
temporary state in policy or authentication then a 
Send-Map-Request
action with 1-minute TTL MAY be returned to allow the 
reqeustor to
retry the Map-Request.

Could I not do the above even if the EID-prefix DID NOT EXIST? Or are we 
restricting any application of policy only to LISP EID-prefixes, and not to 
non-LISP prefixes?

The map-replies suggested in the new text would effectively be NMRs, correct? 
i.e. Map-replies with empty locator sets and the ACT bits set.

If that is the intent, maybe we need to revise the definitions for NMR and ACT 
as I think right now there is some inconsistency/contradiction:

a) NMR definition - Issued in response to queries only for EIDs that DO NOT 
EXIST
b) ACT bits specification - for use in NMRs ONLY
c) New text describing how the ACT bits are used to specify forwarding behavior 
for EIDs that DO EXIST

So NMRs are exclusive to non-existent or non-registered EIDs (a) and ACT bits 
are exclusive to NMRs (b). Yet (c) implies that NMRs will be used for EIDs that 
DO EXIST. So (c) contradicts (a).

Text for (a)

   Negative Map-Reply:   A LISP Map-Reply that contains an empty
  Locator-Set. Returned in response to a Map-Request if the
  destination EID does not exist in the mapping database.
  Typically, this means that the "EID" being requested is an IP
  address connected to a non-LISP site.

Text for (b)

   ACT:  This 3-bit field describes Negative Map-Reply actions.  In any
  other message type, these bits are set to 0 and ignored on
  receipt.  These bits are used only when the 'Locator Count' field
  is set to 0.  The action bits are encoded only in Map-Reply
  messages.  The actions defined are used by an ITR or PITR when a
  destination EID matches a negative Map-Cache entry.  Unassigned
  values SHOULD cause a Map-Cache entry to be created, and when
  packets match this negative cache entry, they will be dropped.


-v

On Mar 20, 2018, at 12:44 AM, Dino Farinacci 
mailto:farina...@gmail.com>> wrote:

On Mar 19, 2018, at 6:22 PM, Dino Farinacci 
mailto:farina...@gmail.com>> wrote:

Dear WG,

I did a quick review of rfc6833bis-08. Some comments/suggestions

Thanks Victor. See new update enclosed. Let us know if you are good with the 
changes and the response below.

1. Section 5.8. Encapsulated Control Message Format. There is a reference to 
LH, it is not spelled out anywhere. I assume this means Lisp Header.

It is a reference to the row in the diagram above:



Understood, but should we not spell out LISP Header somewhere rather than just 
using LH without spelling it out anywhere?

I can change it. See new diff.


3. Section 8.3/8.4. The text is limited to recommending exclusively a Native 
Forward action code. However the definition of the Map-reply message in section 
5.4 allows 8 possible action codes and specifies 6 possible actions. If the WG 
agrees I can suggest text that would generalize the recommended processing 
behaviors described in 8.3 to allow the inclusion and use of the specified 
actions in the case of NMRs.

Well the text below is correct and is explaining when a mapping entry DOES NOT 
exist. For all other actions, they are sent for entries that DO EXIST in the 
mapping database. And the reasons for sending the specific action type is 
documented in the Map-Reply ACT field description:

I agree that the text is correct, but I am pointing out that is not sufficient. 
If my policy is to drop traffic destined to an EID that is either not 
registered or not configured in the Mapping DB, how would I instruct the EID to 
drop the traffic? I would think I'd want to issue an NMR with action drop  (4 
or other). The spec currently doesn’t illustrate such actions. Text in 8.3 & 
8.4 prescribes that the NMR for non-configured or non-registered EIDs will 
always have an action of Native-Forward, but I need the action to be Drop (for 
example).

In the definitions section, the NMRs are defined as responses to queries for 
EIDs that DO NOT EXIST, in the text you pasted below, the ACT bits are defined 
as exclusive to the NMRs (set to 0 in any other message).  It is not clear to 
me how these actions can apply to entries that DO EXIST?

-v

Okay, I added some text.

Dino



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Re: [lisp] Review 6833bis-08 - General and NMR

[Victor Moreno (vimoreno)]

> On Mar 19, 2018, at 6:22 PM, Dino Farinacci  wrote:
> 
>> Dear WG,
>> 
>> I did a quick review of rfc6833bis-08. Some comments/suggestions
> 
> Thanks Victor. See new update enclosed. Let us know if you are good with the 
> changes and the response below.
> 
>> 1. Section 5.8. Encapsulated Control Message Format. There is a reference to 
>> LH, it is not spelled out anywhere. I assume this means Lisp Header.
> 
> It is a reference to the row in the diagram above:
> 
> 

Understood, but should we not spell out LISP Header somewhere rather than just 
using LH without spelling it out anywhere?

> 
> 
>> 2. Section 5.8. On page 27, there is a figure/header format showing the AD 
>> Type and Authentication Data Content, which is not referenced anywhere. 
>> Looks like it needs to be removed.
> 
> Nice find. When the text was moved from RFC6830, we mis-placed it in RFC6833.

Ack, good.

> 
>> 3. Section 8.3/8.4. The text is limited to recommending exclusively a Native 
>> Forward action code. However the definition of the Map-reply message in 
>> section 5.4 allows 8 possible action codes and specifies 6 possible actions. 
>> If the WG agrees I can suggest text that would generalize the recommended 
>> processing behaviors described in 8.3 to allow the inclusion and use of the 
>> specified actions in the case of NMRs. 
> 
> Well the text below is correct and is explaining when a mapping entry DOES 
> NOT exist. For all other actions, they are sent for entries that DO EXIST in 
> the mapping database. And the reasons for sending the specific action type is 
> documented in the Map-Reply ACT field description:

I agree that the text is correct, but I am pointing out that is not sufficient. 
If my policy is to drop traffic destined to an EID that is either not 
registered or not configured in the Mapping DB, how would I instruct the EID to 
drop the traffic? I would think I'd want to issue an NMR with action drop  (4 
or other). The spec currently doesn’t illustrate such actions. Text in 8.3 & 
8.4 prescribes that the NMR for non-configured or non-registered EIDs will 
always have an action of Native-Forward, but I need the action to be Drop (for 
example).

In the definitions section, the NMRs are defined as responses to queries for 
EIDs that DO NOT EXIST, in the text you pasted below, the ACT bits are defined 
as exclusive to the NMRs (set to 0 in any other message).  It is not clear to 
me how these actions can apply to entries that DO EXIST? 

-v

> 
>  ACT:  This 3-bit field describes Negative Map-Reply actions.  In any
>  other message type, these bits are set to 0 and ignored on
>  receipt.  These bits are used only when the 'Locator Count' field
>  is set to 0.  The action bits are encoded only in Map-Reply
>  messages.  The actions defined are used by an ITR or PITR when a
>  destination EID matches a negative Map-Cache entry.  Unassigned
>  values SHOULD cause a Map-Cache entry to be created, and when
>  packets match this negative cache entry, they will be dropped.
>  The current assigned values are:
> 
>  (0) No-Action:  The Map-Cache is kept alive, and no packet
>  encapsulation occurs.
> 
>  (1) Natively-Forward:  The packet is not encapsulated or dropped
>  but natively forwarded.
> 
>  (2) Send-Map-Request:  The packet invokes sending a Map-Request.
> 
>  (3) Drop/No-Reason:  A packet that matches this Map-Cache entry is
>  dropped.  An ICMP Destination Unreachable message SHOULD be
>  sent.
> 
>  (4) Drop/Policy-Denied:  A packet that matches this Map-Cache
>  entry is dropped.  The reason for the Drop action is that a
>  Map-Request for the target-EID is being policy denied by
>  either an xTR or the mapping system.
> 
>  (5) Drop/Authentication-Failure:  A packet that matches this Map-
>  Cache entry is dropped.  The reason for the Drop action is
>  that a Map-Request for the target-EID fails an authentication
>  verification-check by either an xTR or the mapping system.
> 
> Thanks again,
> Dino
> 
> 
> 
> 

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Re: [lisp] Review 6833bis-08 - General and NMR

[Victor Moreno (vimoreno)]

These comments apply to version -09 of the document without any change.

-v


On Mar 19, 2018, at 2:18 PM, Victor Moreno (vimoreno) 
mailto:vimor...@cisco.com>> wrote:

Dear WG,

I did a quick review of rfc6833bis-08. Some comments/suggestions



1. Section 5.8. Encapsulated Control Message Format. There is a reference to 
LH, it is not spelled out anywhere. I assume this means Lisp Header.

2. Section 5.8. On page 27, there is a figure/header format showing the AD Type 
and Authentication Data Content, which is not referenced anywhere. Looks like 
it needs to be removed.

3. Section 8.3/8.4. The text is limited to recommending exclusively a Native 
Forward action code. However the definition of the Map-reply message in section 
5.4 allows 8 possible action codes and specifies 6 possible actions. If the WG 
agrees I can suggest text that would generalize the recommended processing 
behaviors described in 8.3 to allow the inclusion and use of the specified 
actions in the case of NMRs.

   8.3.  Map-Server Processing
   Once a Map-Server has EID-Prefixes registered by its client ETRs, it
   can accept and process Map-Requests for them.
   In response to a Map-Request (received over the ALT if LISP+ALT is in
   use), the Map-Server first checks to see if the destination EID
   matches a configured EID-Prefix.  If there is no match, the Map-
   Server returns a Negative Map-Reply with action code "Natively-
   Forward" and a 15-minute TTL.  This MAY occur if a Map Request is
   received for a configured aggregate EID-Prefix for which no more-
   specific EID-Prefix exists; it indicates the presence of a non-LISP
   "hole" in the aggregate EID-Prefix.
   Next, the Map-Server checks to see if any ETRs have registered the
   matching EID-Prefix.  If none are found, then the Map-Server returns
   a Negative Map-Reply with action code "Natively-Forward" and a
   1-minute TTL.

   8.4 …

   If the Map-Resolver does not have the mapping entry and if it can
   determine that the EID is not in the mapping database (for example,
   if LISP+ALT is used, the Map-Resolver will have an ALT forwarding
   table that covers the full EID space), it immediately returns a
   negative LISP Map-Reply, with action code "Natively-Forward" and a
   15-minute TTL.  To minimize the number of negative cache entries
   needed by an ITR, the Map-Resolver SHOULD return the least-specific
   prefix that both matches the original query and does not match any
   EID-Prefix known to exist in the LISP-capable infrastructure.


Regards,

-v





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