[speaking as WG participant]

Hi Acee, All,

The current draft needs some work to be better readable. It is a non-trivial 
read. I am convinced that when there is consensus to develop the leaderless 
solution that this can be worked out accordingly. In my opinion, the greatest 
advantage of a leaderless technology architecture is its operational 
simplicity, particularly because it eliminates the need for a coordinated 
transition or "flag day."

A few benefits I see from a leaderless approach:


  *   Enhanced Redundancy: Multiple nodes participate in flooding, reducing the 
risk associated with any single node failure.
  *   Simpler Protocol Design: Eliminates the need for leader election and 
maintenance mechanisms, simplifying the protocol implementation.
  *   Better Scalability: Distributes the processing load across multiple 
nodes, preventing bottlenecks.
  *   Faster Convergence: Avoids delays associated with leader re-election, 
enabling quicker dissemination of routing updates.

Some concerns I see with a flooding leader approach:

  *   Single Point of Failure (the flooding leader becomes a critical component 
in the network. If the leader fails or becomes unreachable, it can disrupt the 
flooding process until a new leader is elected or the network converges to an 
alternative state)
  *   Increased Complexity (Implementing a flooding leader requires additional 
mechanisms for leader election, maintenance, and failure detection)
  *   Scalability Concerns (in large-scale or highly dynamic networks, managing 
a single flooding leader can become a bottleneck)
  *   Convergence Delays (when the flooding leader fails, the network must 
initiate a leader re-election process)
  *   Lack of Redundancy (relying on a single leader reduces redundancy in the 
flooding process)
  *   Overhead of Leader Maintenance (continuous monitoring is required to 
ensure the flooding leader is operational)
  *   Potential for Suboptimal Flooding Paths (the flooding leader may not 
always have the most efficient paths to all nodes, especially in dynamic 
topologies)
  *   Complex Recovery Mechanisms (recovering from leader failures may involve 
complex procedures that differ from standard link-state protocol operations)

I believe there is place for both a flooding leader and leaderless 
architecture. It depends upon type of network where this is implemented (for 
example Datacenter or Service Provider WAN).

Be well,
G/

From: Acee Lindem <[email protected]>
Sent: Monday, November 18, 2024 3:40 PM
To: lsr <[email protected]>
Subject: [Lsr] Consensus Call on LSR WG work on "Leaderless Flooding Algorithm 
for Distributed Flood Reduction to allow reduced configuration, minimal blast 
radius, and ease of incremental deployment"


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During the IETF 121 LSR meeting, we had a very good discussion of 
https://datatracker.ietf.org/doc/draft-ietf-lsr-distoptflood/

While the CDS flooding reduction algorithm itself was interesting, the main 
area of the discussion was distributed flooding reduction algorithm selection 
and its configuration and deployment.

Today, we have RFC 9667 "Dynamic Flooding on Dense Graphs" which provides 
leader-based supporting both centralized and distributed flooding reduction 
algorithm selection. With the mechanism, an area leader is selected from among 
the OSPF routers in the area supporting flooding reduction and this leader 
selects the flooding reduction algorithm for the area.

The question to be answered by this consensus call is whether or not we want to 
work on an additional mechanism just for distributed flooding reduction to 
allow for reduced configuration, minimal blast radius, and ease of incremental 
deployment.

Please send your support or opposition to this list before Tuesday, December 
3rd.

As WG Co-Chair,
Acee
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