Hello Lyle,
Thanks for the detailed reply. It clears up a lot of questions in my
mind. To briefly reply:
- The reason I was asking about whether or not an Interface Group lived
on a DPN was to help me figure out how to structure the Interface Group
definition. It's already structured as an Indexed Set, and so we will
have an Interface-Group-Key. The DPN structure will have a list of such
keys, for each Interface Group that exists and includes an Interface
from the DPN. I think this is O.K. for your scenario of different
security zones. Notably, we do not provide that as an attribute of an
Interface, but then again I don't think we could reasonably be expected
to delineate all possible attributes of Interfaces.
An Interface Group will also have a DPN-Key, for the DPN that hosts its
interfaces.
Your example about having to select a DPN to handle emergency calls as
well as "normal" call processing is very interesting. What if we make
that to be two different access-network features, and enable selection
of Interface Groups for each feature? Then we are still O.K. with
having each Interface Group to be configured with only one DPN-Key.
Regards,
Charlie P.
On 1/22/2018 1:49 PM, Bertz, Lyle T [CTO] wrote:
Your scenarios are correct. I think we are in agreement but I want to
clarify a few things:
Wrt your statement “(b) it makes good sense for all the Interfaces of
an Interface Group to be hosted on the same DPN.”
Ack. I agree when the required interfaces within an Interface Group
can be hosted on the same DPN to service a request. However, we leave
DPN selection up to the implementations as they may have proprietary
or other perfectly good reasons not to do this. By the above
statement I have interpreted it as a recommendation and not a mandate,
i.e. it is not a requirement in FPC to do this. Is that correct?
Wrt the statement “I just want all of the Interfaces of an Interface
Group to be on the same DPN”
I wish that was always the case but when the interface types are
different or have a different purpose, e.g. normal calls vs. emergency
calls, this is not the case in practice.
In the model then are you proposing the Interface Groups only reside
under the DPN structure? If so, then one must load all DPNs and index
them by Interface Groups Id to determine they are from the same
group. The purpose in pulling them out was to create a single Set
that could be used to house the typing and common configuration
information. DPN interfaces assigned to support an Interface Group are
then assigned to it. Thus, if a DPN had 2 interfaces which are of the
same type but in different security zones (or have different
routes/networks served) they may not be able to serve in the same group.
Lyle
*From:*Charlie Perkins [mailto:[email protected]]
*Sent:* Monday, January 22, 2018 3:25 PM
*To:* Bertz, Lyle T [CTO] <[email protected]>
*Cc:* [email protected]
*Subject:* Re: Question about Interface Groups (formerly, DPN Groups)
Hello Lyle,
I agree that:
1. - Interface Groups are designed to be used to select DPN.
2. - Interface Groups may contain a number of different Interface Types
3. - There may be more than one Interface Group providing equivalent
service, at least for the purpose of selecting a DPN.
For (1) -- I imagine that the selection process would look to make
sure that the Interface Group has the proper interfaces that are
needed (say, by the FPC Client). Then, the FPC Client would select
the DPN hosting the Interface Group, set up connectivity with the
interfaces in the Peer Interface Group(s), and all is good.
For (2) -- this is really the motivation for the concept of Interface
Groups.
For (3) -- really a follow-on from (1): the FPC Client would then look
at the other properties of the DPN hosting the Interface Group, to
determine which was the least cost, or highest benefit, choice. Or
alternatively the FPC Client would look at the Settings on the
Interfaces of the Group, to see which Interfaces had the best fit for
the purposes of the FPC Client.
If I have these scenarios right, then (a) we don't need to introduce
any further virtual DPN definitions for proper operation and (b) it
makes good sense for all the Interfaces of an Interface Group to be
hosted on the same DPN.
The intent of the structure is for use during DPN selection. To
maintain it as a DPN means some DPNs are used during selection but
others are not.
I agree with this completely, if I understand it. After the selection
occurs based on the suitability of the Interface Group, its function
is done. I did not in any way mean to suggest that the Interface
Group was ever going to be a DPN or a virtual DPN.
I just want all of the Interfaces of an Interface Group to be on the
same DPN.
Regards,
Charlie P.
On 1/22/2018 11:36 AM, Bertz, Lyle T [CTO] wrote:
k. I think that we are crossing conversations now.
“An Interface Group on a DPN would also have have attributes for
Peer Interface Groups residing on other DPNs. ” < Did not see that.
Interface Groups (aka DPN Groups) can be used for DPN pool
selection (multiple options) with a different interface strategy.
Interface Groups (aka DPN Groups) may also contain hetergeneous
DPN-Type (interface types). In this case the totality of services
could be provided by more than one DPN.
If we say that this is ‘just a virtual DPN with a selection
strategy of multiple underlying DPNs” I feel that we are jamming
too many concepts into the DPN. Overloading is okay until one is
overloaded ;)
The intent of the structure is for use during DPN selection. To
maintain it as a DPN means some DPNs are used during selection but
others are not.
I would propose that we keep this concept separate for now, look
at proposed changes and then revisit this issue.
*From:*Charlie Perkins [mailto:[email protected]]
*Sent:* Monday, January 22, 2018 12:07 PM
*To:* Bertz, Lyle T [CTO] <[email protected]>
<mailto:[email protected]>
*Cc:* [email protected] <mailto:[email protected]>
*Subject:* Re: Question about Interface Groups (formerly, DPN Groups)
Hello Lyle,
An Interface Group on a DPN would also have have attributes for
Peer Interface Groups residing on other DPNs. So, the data plane
configuration can already exhibit the ("cross-DPN")
interconnection between Interface Groups even if the interfaces of
the Group all reside on the same DPN.
Could you give an example of an Interface Group that perforce
requires to reside on multiple DPNs? Is it a case that could be
handled better by defining a virtual DPN to host the Interface
Group? I understand the word "containment" but I'm not at all
clear about what sort of Group requires the extra complication to
expedite the stated purpose, which is DPN selection. If there are
other purposes, I would be inclined to define other structures for
them that do not have the effect of complicating the Interface
Group definition.
Regards,
Charlie P.
On 1/22/2018 5:11 AM, Bertz, Lyle T [CTO] wrote:
<adding mailing list>
No, I don’t think they should reside under a DPN. Groups
like these also span multiple DPNs which would make
containment graphs far too confusing.
*From:*Charlie Perkins [mailto:[email protected]]
*Sent:* Sunday, January 21, 2018 10:51 PM
*To:* Bertz, Lyle T [CTO] <[email protected]>
<mailto:[email protected]>
*Cc:* Marco Liebsch <[email protected]>
<mailto:[email protected]>; Satoru Matsushima
<[email protected]>
<mailto:[email protected]>; Sri Gundavelli
(sgundave) <[email protected]> <mailto:[email protected]>;
Moses, Danny <[email protected]>
<mailto:[email protected]>; Weaver, Farni [CTO]
<[email protected]> <mailto:[email protected]>;
Matsushima Satoru <[email protected]>
<mailto:[email protected]>
*Subject:* Question about Interface Groups
Hello folks,
Can we have it so that all the Interfaces of an "Interface
Group" (formerly, "DPN Group") reside on the same DPN?
If so, I can make good sense out of the text in the document,
but otherwise I think there are big problems.
I have some other questions, but this is the main thing right
now. If the answer to my question is "Yes" I think I will
have a sensible revision tomorrow.
I have some more questions, not quite as important, which I
will put in separate emails.
Regards,
Charlie P.
On 1/18/2018 5:26 AM, Bertz, Lyle T [CTO] wrote:
Charlie,
Glad to hear things are going well. I’m looking forward
to your document update.
Lyle
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