Subject: Re: [DMM] draft requirement REQ-1: Distributed deployment

From: h chan <[email-masked]>
Date: Fri, 15 Jun 2012 02:19:34 +0000

Changed SHALL to MUST.
Clean up text:

   REQ1:  Distributed deployment

          IP mobility, network access and routing solutions provided by
          DMM MUST enable a distributed deployment of mobility
          management of IP sessions so that the traffic can be routed in
          an optimal manner without traversing centrally deployed
          mobility anchors.

          Motivation: The motivations of this requirement are to match
          mobility deployment with current trend in network evolution:
          more cost and resource effective to cache and distribute
          contents when combining distributed anchors with caching
          systems (e.g., CDN); improve scalability; avoid single point
          of failure; mitigate threats being focused on a centrally
          deployed anchor, e.g., home agent and local mobility anchor.

   This requirement addresses the following problems PS1, PS2, PS3, and
   PS4.

   PS1:  Non-optimal routes

         Routing via a centralized anchor often results in a longer
         route, and the problem is especially manifested when accessing
         a local or cache server of a Content Delivery Network (CDN).

   PS2:  Non-optimality in Evolved Network Architecture

         The centralized mobility management can become non-optimal as a
         network architecture evolves and becomes more flattened.

   PS3:  Low scalability of centralized route and mobility context
         maintenance

         Setting up such special routes and maintaining the mobility
         context for each MN is more difficult to scale in a centralized
         design with a large number of MNs.  Distributing the route
         maintenance function and the mobility context maintenance
         function among different networks can be more scalable.

   PS4:  Single point of failure and attack

         Centralized anchoring may be more vulnerable to single point of
         failure and attack than a distributed system.

H Anthony Chan

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of h chan
Sent: Wednesday, May 23, 2012 6:35 PM
To: jouni korhonen
Cc: [email-masked]
Subject: Re: [DMM] draft requirement REQ-1: Distributed deployment

o "centrally deployed anchors" what if the access network routing is laid
  out in a way that even pure IP routing would lead packets to go through a 
  central site/edge router? Doesn't that lead to similar deficiencies than
  with mobility anchors?

Let us call it "centrally deployed mobility anchors" in the requirement. 

H Anthony Chan

-----Original Message-----
From: jouni korhonen [mailto:[email-masked]] 
Sent: Thursday, May 17, 2012 6:46 PM
To: h chan
Cc: [email-masked]
Subject: Re: [DMM] draft requirement REQ-1: Distributed deployment

Breaking the silence..

On May 7, 2012, at 8:55 PM, h chan wrote:

> REQ-1: Distributed deployment
> IP mobility, network access and routing solutions provided by DMM SHALL enable the functions of mobility management of IP sessions to be distributed so that the traffic is routed in an optimal manner without relying on centrally deployed anchors.

Few comments/questions..
o "SHALL enable the functions of mobility management" does that imply the
  DMM "solution" must always involve or extend a mobility protocol? IMHO
  that should not be a SHALL requirement.

o "centrally deployed anchors" what if the access network routing is laid
  out in a way that even pure IP routing would lead packets to go through a 
  central site/edge router? Doesn't that lead to similar deficiencies than
  with mobility anchors?

>  
> REQ-1M (Motivation for REQ-1)
> The goals of this requirement are to
> match mobility deployment with current trend in network evolution: more cost and resource effective to cache and distribute contents when combining distributed anchors with caching systems (e.g., CDN); improve scalability; reduce signaling overhead; avoid single point of failure; mitigate threats being focused on a centrally deployed anchor, e.g., home agent and local mobility anchor.

Reduce signaling overhead.. is a very good goal. However, if any DMM
solution builds on top of an existing mobility protocol that hardly
reduces anything. Also if setting up optimal routes require establishing
new tunnels, signaling is bound to increase. I would say here "does not
increase the amount of present signaling" and the aim for solutions that
would reduce it somehow.

>  
> RELEVANT problems:
> PS1: Non-optimal routes
> Routing via a centralized anchor often results in a longer route, and the problem is especially manifested when accessing a local or cache server of a Content Delivery Network (CDN).
> PS2: Non-optimality in Evolved Network Architecture
> The centralized mobility management can become non-optimal as Network architecture evolves and become more flattened.

More flat is kind of superfluous.. take e.g. EPS example. You have, in an optimal
case, an eNodeB connected directly to a combined SGW/PGW from the user plane point
of view. And the SGW/PGW you can allocate close to you eNodeB based on its topological
location. How you can make that more flat? SGW relocation changes the situation a bit
but still..

> PS3: Low scalability of centralized route and mobility context maintenance
> Setting up such special routes and maintaining the mobility context for each MN is more difficult to scale in a centralized design with a large number of MNs.

Can I assume the mobility context involves a possible per MN tunnel state?

> Distributing the route maintenance function and the mobility context maintenance function among different networks can be more scalable.
> PS4: Single point of failure and attack
> Centralized anchoring may be more vulnerable to single point of failure and attack than a distributed system.
>  
> (The above is drafted with contributions, inputs and discussions from various people. Additional contributions and comments are most welcome.)
>  

- Jouni

> H Anthony Chan
> 
>  
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