Router State Synchronization for Serial Data Links Over IP
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Solution Overview
Problem
Existing systems that transport serial communications over IP networks lose end-to-end state visibility, leading to synchronization issues and resource wastage due to unnecessary restarts when one end point is down, causing network flapping and complicating debugging.
Innovation Solution
Implementing a state machine within routers to synchronize serial data link states across IP networks by communicating link states through OAM messages, defining a 'ready' state to prevent unnecessary restarts and maintain accurate end-point visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If serial data links are transported over IP networks using router emulation, then connectivity and flexibility are improved, but state synchronization and endpoint visibility deteriorate
Solution Approach 1:
The patent implements a feedback mechanism where routers exchange operational status messages (OM1, OM2, OM3) with remote routers to maintain synchronized state information across the IP network. This feedback loop ensures that when one endpoint goes down, the other endpoint is notified and can take appropriate action, preventing state desynchronization while maintaining IP network connectivity.
2Ease of operation
If conventional restart procedures are used in IP-transported serial links, then session re-initialization is simplified, but resource wastage and network flapping increase
Solution Approach 1:
The patent applies preliminary action by proactively notifying the remote endpoint of an impending session shutdown before it occurs. When one endpoint detects a session termination, it sends an operational status message to the remote router, which then prevents unnecessary restart attempts. This preliminary notification eliminates resource-wasting flapping behavior while maintaining simple restart procedures when actually needed.
3Adaptability or versatility
If endpoint states are not synchronized across IP networks, then routing flexibility is maintained, but debugging complexity and session management difficulty increase
Solution Approach 1:
The patent uses operational status messages (OM1, OM2, OM3) as visual indicators of session state, analogous to color changes. These standardized messages provide clear, unambiguous state information that can be easily monitored and debugged. OM1 indicates normal operation, OM2 indicates session shutdown, and OM3 indicates session restoration, making it simple to track session states across the IP network without sacrificing routing flexibility.
Data Source
AI summary
In one embodiment, a router maintains a communication session between a local terminal unit and a remote terminal unit, the local terminal unit interconnected to the router over a local serial data link, and the remote terminal unit interconnected to the router over an Internet Protocol (IP) session via a remote router and a corresponding remote serial data link. The router may then monitor a state of the local serial data link, and communicates this state with the remote router over the IP session, as well as a remote state of the remote serial data link. The router may then correspondingly control the state of the local serial data link to match the remote state of the remote serial data link.