Subject: Re: [netext] Review of I-D: draft-ietf-netext-pd-pmip6-06

From: [email-masked]
Date: Mon, 20 May 2013 17:38:56 +0800

Hello Raj,

Thanks for your review.

A new version (-08) of the draft has been submitted. Your comments below 
are addressed in this version.

The draft is ready for WGLC now. Thanks.

Best Regards,
Joy

Basavaraj Patil <[email-masked]> 
发件人:  [email-masked]
2013-04-04 01:59

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[netext] Review of I-D: draft-ietf-netext-pd-pmip6-06

Questions:

1. In the terminology section:
   "The DMNP is an IPv4 or an IPv6 prefix delegated to a mobile router
      and advertised in the mobile network."

      What is the mobile network being refered to in this statement?
      Is it the PMIP6 domain itself? Or is it the network that the
      mobile router is hosting?

2. In Sec 4.3.1:
   "It is possible that the delegated prefix(es) may
       have been assigned to the MAG by the LMA during this procedure of
       PMIPv6 tunnel establishment.  That is the MAG may include one (or
       more) Delegated Mobile Network Prefix (DMNP) mobility options
       which MUST be set to the unspecified IPv6 address "::" in the PBU
       to request the delegated prefix(es).  The LMA assigns a new set
       of DMNP(s) in PBA message."

       Not sure what your assumptions are here. Why does the LMA
       assign delegated prefix(es) during normal RFC5213 PMIP6 tunnel
       establishment procedures?
       What would cause the MAG to include the DMNP option in the PBU
       at this stage (Step 2) of the session?

3. In Sec 4.3.1:
   " The mobile router, acting as a "Requesting Router" as described
       in [RFC3633], sends a DHCPv6 SOLICIT message including one or
       more IA_PD option(s) to the mobile access gateway (which has a
       "DHCPv6 Server" function) to acquire the delegated prefix(es)."

       Is there an assumption that the MAG is also the DHCPv6 server?
       The MAG could be a DHCP relay as well, right?

4. In Sec 4.3.1, step 5:
   "The LMA must set
       up forwarding for the delegated prefixes as reachable through the
       PMIPv6 tunnel."

       The LMA may or may not assign these delegated prefixes. The MAG
       could be the one assigning the delegated prefixes as per the
       description. Are those prefixes routable by the LMA?

5. In Sec 4.4.1, step 4:
   "If the mobile access
        gateway does not know the delegated prefix(es), then the
        delegated mobile network prefix in the DMNP option(s) MUST be
        set to the unspecified IPv6 address "::", "

How would the MAG know the delegated prefix(es)? Unless it is
just renewing the assigned prefix(es)?

6. Is the assumption that the DHCP server functionality resides either
   at the MAG or the LMA in this I-D?

7. In Sec 6.2 you state:
   "In order to receive these packets, the
      local mobility anchor MUST be the topological anchor of the MR's
      delegated mobile network prefix(es)."

      This should be made clear up front in order to avoid confusion
      about how forwarding is accomplished.

Editorial:

s/Proxy Mobile IPv6 enables IP mobility for a host without requiring
   its participation in any mobility signaling, being the network
   responsible for managing IP mobility on behalf of the host./ Proxy
   Mobile IPv6 enables IP mobility for a host without requiring 
   its participation in any mobility signaling. Mobility elements in
   the network are responsible for managing IP mobility on behalf of
   the host. 

s/However,
   Proxy Mobile IPv6 does not support assigning a prefix to a router and
   managing its IP mobility./However, Proxy Mobile IPv6 lacks the
   ability to assign a prefix to a router and  manage its IP
   mobility. 

s/and be able to obtain IP mobility support for those IP addresses./
   and enable IP mobility support for the assigned IP address or
   prefixes. 

s/However,
   this network-based mobility management support is specific to an IP
   host and currently there is no such network-based mobility management
   support for a mobile router with a cluster of IP hosts behind 
it./However,
   the Proxy Mobile IPv6 based solution for  network-based mobility
   management is specific to IP hosts and does not provide similar
   functionality for a mobile router with a cluster of IP hosts behind
   it. 

-Raj
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---

From: Carlos Jesús Bernardos Cano <[email-masked]>
Date: Mon, 20 May 2013 17:04:23 +0200

Hi Raj,

Some additional responses inline below (as Joy mentioned, we believe
that everything is clearer in the new version, but just in case).

>       mobile router is hosting?

[Carlos] It is the network that the mobile router is hosting.
>        at this stage (Step 2) of the session?

[Carlos] We have clarified this in the new version.
>        The MAG could be a DHCP relay as well, right?

[Carlos] Right, two deployment models are considered: one in which the
MAG acts a DHCPv6 Delegating Router (i.e., server) and another in which
the MAG acts as DHCPv6 Relay Agent and the LMA as Delegating Router.
This has been further clarified in the new version.
>        description. Are those prefixes routable by the LMA?

[Carlos] Yes, the prefixes are routable by the LMA.
> just renewing the assigned prefix(es)?

[Carlos] This has been further revised and clarified in the new version.
>    at the MAG or the LMA in this I-D?

[Carlos] Yes. It should be now clearer with the updates we have done in
the text.
>       about how forwarding is accomplished.
[Carlos] This should be now clear.
Thanks for your comments!

Carlos

---

From: "Sri Gundavelli (sgundave)" <[email-masked]>
Date: Mon, 20 May 2013 15:26:19 +0000

Hi Raj,

Adding to what carlos said. Just one clarification.

>> just renewing the assigned prefix(es)?

The prefixes can be statically configured in the policy profile. Typically
mobile networks are statically configured (but registered with the LMA) as
we don't want the prefixes to disappear if the egress link goes down and
that will result in local communication between the hosts to break. So,
the prefixes are statically provisioned in the mobile network. But,
mobility support comes up only when there is active session with LMA
enabling the forwarding.

If the MAG knows the prefixes, it can indicate them in the DMNP option.
If the MAG does not know the prefixes,  it will carry a NULL value.
LMA assigns them based on what is in the BCE state.

This is consistent with how the home address (IPv4 HoA, HNP) options are
carried in PMIP signaling messages.

Regards
Sri

---

From: Basavaraj Patil <[email-masked]>
Date: Wed, 22 May 2013 14:40:35 -0500

Hi Carlos et al,

My comments inline:

> [Carlos] It is the network that the mobile router is hosting.

Raj> Okay.
However the current statement in the I-D:
"

The Delegated Mobile Network Prefix is an IPv4/IPv6 prefix
delegated to a mobile router and is hosted in the mobile network.

"
Would be better to say that this prefix is hosted by the PMIP6 mobility
agent, i.e LMA.

> [Carlos] We have clarified this in the new version.

Raj> Section 4.3.1 no longer exists. Would have been easier if the revised
section was pasted here :(

> This has been further clarified in the new version.

Raj> Okay.. Good.

> [Carlos] Yes, the prefixes are routable by the LMA.

Raj> How?? Are those prefixes which the MAG delegates also anchored at the
LMA?

> [Carlos] This has been further revised and clarified in the new version.

Raj> What is the new section in the document? Sec 4.4.1 is no longer there.

> [Carlos] Yes. It should be now clearer with the updates we have done in

Raj> Okay.

> [Carlos] This should be now clear.

Raj> Can you point me to the new text that clarifies this?

-Raj

-- 
Basavaraj Patil

---

From: Basavaraj Patil <[email-masked]>
Date: Wed, 22 May 2013 14:49:00 -0500

Inline:

> carried in PMIP signaling messages.
Raj>  What does this mean: "Typically
mobile networks are statically configured (but registered with the
LMA)...."?

Also: "So,
the prefixes are statically provisioned in the mobile network."

Would be good if you can clarify since you have a view or interpretation
that I am not sure everyone is in sync with.

-Raj

---

From: "Sri Gundavelli (sgundave)" <[email-masked]>
Date: Wed, 22 May 2013 21:01:06 +0000

Hi Raj,

Inline …

From: Basavaraj Patil <[email-masked]<mailto:[email-masked]>>
Date: Wednesday, May 22, 2013 12:49 PM
To: Sri Gundavelli <[email-masked]<mailto:[email-masked]>>
Cc: "[email-masked]<mailto:[email-masked]>" <[email-masked]<mailto:[email-masked]>>, "[email-masked]<mailto:[email-masked]>" <[email-masked]<mailto:[email-masked]>>, "[email-masked]<mailto:[email-masked]>" <[email-masked]<mailto:[email-masked]>>
Subject: Re: [netext] Review of I-D: draft-ietf-netext-pd-pmip6-06

Inline:

On Mon, May 20, 2013 at 10:26 AM, Sri Gundavelli (sgundave) <[email-masked]<mailto:[email-masked]>> wrote:
Hi Raj,

Raj>  What does this mean: "Typically
mobile networks are statically configured (but registered with the LMA)...."?

Also: "So,

Would be good if you can clarify since you have a view or interpretation that I am not sure everyone is in sync with.

[Sri] I'm just saying, the subnets (DMNP's) are configured manually in the mobile network. But, those subnets belong to the LMA from routing point of view. This is almost like a static IP configuration.
There is also the other approach, every thing happens dynamically, the prefix is obtained from the LMA/MAG and then gets configured in the mobile network.
In most deployments, IMO, static configuration is preferred as they don't want the networks/prefixes to disappear, if the LMA is not reachable and the PMIP tunnel goes down. There won't be IP mobility or external reachability, but there will be internal node to node communication.

Regards
Sri

---

From: Basavaraj Patil <[email-masked]>
Date: Thu, 23 May 2013 09:16:28 -0500

Inline:

On Wed, May 22, 2013 at 4:01 PM, Sri Gundavelli (sgundave) <
[email-masked]> wrote:

>  [Sri] I'm just saying, the subnets (DMNP's) are configured manually in
> the mobile network. But, those subnets belong to the LMA from routing point
> of view. This is almost like a static IP configuration.
> There is also the other approach, every thing happens dynamically, the
> prefix is obtained from the LMA/MAG and then gets configured in the mobile
> network.
> In most deployments, IMO, static configuration is preferred as they don't
> want the networks/prefixes to disappear, if the LMA is not reachable and
> the PMIP tunnel goes down. There won't be IP mobility or external
> reachability, but there will be internal node to node communication.
>
>  Regards
> Sri
>

Raj> Well, okay. I get that. But from reading the text in the I-D it is not
very clear. Would recommend reworking the text to explain the above.

-Raj

-- 
Basavaraj Patil

---

From: Carlos Jesús Bernardos Cano <[email-masked]>
Date: Thu, 23 May 2013 19:54:55 +0200

Hi Raj, all,

Some answers inline below.

On Wed, 2013-05-22 at 14:40 -0500, Basavaraj Patil wrote:
> Hi Carlos et al,
> 
> 
> My comments inline:
> 
> 
> 
> 
> On Mon, May 20, 2013 at 10:04 AM, Carlos Jesús Bernardos Cano
> <[email-masked]> wrote:
>         Hi Raj,
>         
> Would be better to say that this prefix is hosted by the PMIP6
> mobility agent, i.e LMA. 
> 
[Carlos] There are two considerations here:

1. The prefix is configured in the mobile network. RA's are sent in
those networks.
2. The LMA advertises that prefix into IGP. The LMA is the routing
anchor, but is not hosting those prefixes. Text below (from Section
5.2.3):

   o  The local mobility anchor MUST advertise a connected route into
      the Routing Infrastructure for the IP prefixes delegated to all of
      the mobile routers that it is serving.  This step essentially
      enables the local mobility anchor to be a routing anchor for those
      IP prefixes and be able to intercept IP packets sent to those
      mobile networks.
>         >        have been assigned to the MAG by the LMA during this
>         procedure
>         > of
>         >        PMIPv6 tunnel establishment.  That is the MAG may
>         include one
>         > (or
>         >        which MUST be set to the unspecified IPv6 address
>         "::" in the
>         > PBU
> Raj> Section 4.3.1 no longer exists. Would have been easier if the
> revised section was pasted here :(

[Carlos] Sorry about this, my fault. We reorganized the document for
readability and so moved sections around. The MAG will include the DMNP
option in the PBU, triggered by:

1) MN's policy profile 
2) Receives a trigger from DHCP module

This is covered in Section 5.1.2.

>         >        up forwarding for the delegated prefixes as reachable
>         through
>         > the
>         >        PMIPv6 tunnel."
>         >
>         >
> Raj> How?? Are those prefixes which the MAG delegates also anchored at
> the LMA?

[Carlos] This is covered in Section 5.2.3. Text below:

5.2.3:
   o  The local mobility anchor MUST advertise a connected route into
      the Routing Infrastructure for the IP prefixes delegated to all of
      the mobile routers that it is serving.  This step essentially
      enables the local mobility anchor to be a routing anchor for those
      IP prefixes and be able to intercept IP packets sent to those
      mobile networks.

> Raj> What is the new section in the document? Sec 4.4.1 is no longer

[Carlos] Again, sorry about this. This is also due to the reorganization
of the document that we have done to improve readability.

If the MAG has the list of delegated prefixes belonging to a session:
- it includes the specific prefix values in the DMNP option

If the MAG does not have the list of delegated prefixes belonging to a
session:
- it includes a value of 0::0 in the DMNP option

> Raj> Can you point me to the new text that clarifies this?

[Carlos] This is clarified in Section 5.2.3:

   o  The local mobility anchor MUST advertise a connected route into
      the Routing Infrastructure for the IP prefixes delegated to all of
      the mobile routers that it is serving.  This step essentially
      enables the local mobility anchor to be a routing anchor for those
      IP prefixes and be able to intercept IP packets sent to those
      mobile networks.

>         >    Proxy Mobile IPv6 does not support assigning a prefix to
>         a router
>         > and
>         >    host and currently there is no such network-based
>         mobility
>         > management

---

From: Basavaraj Patil <[email-masked]>
Date: Thu, 23 May 2013 12:57:39 -0500

Thanks Carlos. That helps.
I am fine with the changes. Will initiate a WG LC on the I-D.

-Raj

-- 
Basavaraj Patil