Subject: [Teas] possible approaches for advanced resource scheduling

From: "Zhuangyan (Yan)" <[email-masked]>
Date: Tue, 5 Jan 2016 08:24:10 +0000

Hi, all,

Best wishes for the new Year, 2016.

Per discussions at IETF 94, the group had a consensus that we were more interested in focusing on a preferably single approach on this problem rather than all possible approaches.
To have a *single* approach for the problem, it may be good to have a discussion on possible approaches through the mailing list first.

The key point/main difference of possible approaches is where to hold the scheduling state. For the centralized approach, the state is held in a central controller where decisions about resource allocation are made. Alternatively, in the distributed approach, the state is held on network nodes where the resources exist.

With this difference, the two approaches act differently when operating in the system. I summarized and compared their respective activities in advanced resource scheduling as below:

Operations

Held in the Network nodes

Held in the central controller

Request/allocation/scheduling resources

The resource reservation can be processed on many points, and is also correlated at the point where the resources are allocated.

Easy. Controller is in charge of allocating/scheduling/responding to requests.

Scaling

each network node must retain the full time-based state for all of its resources.

The controller must retain the state information for its network segment.

Maintenance of the state

the scheduling state information is held on the network nodes and must also be advertised in the IGP and periodically refreshed by the IGP.

In a multiple controller environment, state should be synchronized among controllers.

Recovery

every nodes should provide storage/fault recovery capability for the scheduling state, which costs more.

the state must be held and restored on the control point(s).

According to the comparison, we believe a central approach with few protocol extension and less cost is better for this case. Please feel free to share your thoughts and comments. Thanks.

Best Regards,

Yan