Router Checksum Monitoring for Data Corruption Avoidance
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Solution Overview
Problem
In IP networks, data corruption can occur along routes, but routers lack the ability to detect and avoid corrupted links, leading to retransmission of corrupted packets without identifying the faulty route.
Innovation Solution
Implementing a method where routers receive data packets with an indication to perform a checksum on the entire packet, modifying a value for failed packets, and performing a routing update if the failure rate exceeds a corruption threshold, thereby avoiding transmission over the corrupt link.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If routers only perform checksum on packet headers, then routing processing is fast and simple, but data corruption in payload cannot be detected by routers
Solution Approach 1:
The patent applies preliminary action by having routers pre-compute and store checksum values for entire packets when they first receive them. This pre-computed checksum information is then readily available for rapid corruption detection without requiring full packet re-checksumming, thus maintaining processing speed while enabling reliable corruption detection.
Solution Approach 2:
The patent implements partial action by having routers perform checksum on the entire packet only when corruption is suspected or during initial reception, rather than continuously checking every packet. This selective approach balances the need for reliable detection with the constraint of processing overhead.
2Reliability
If the receiving host detects data corruption and requests retransmission, then data integrity is maintained, but the corrupt route cannot be identified or avoided
Solution Approach 1:
The patent implements feedback by having routers monitor their own packet transmission quality and share this information with neighboring routers through routing updates. When a router detects corruption on an outgoing link, it provides feedback to the network by marking that route as problematic, enabling other routers to avoid the corrupt path and preventing repeated retransmissions.
Solution Approach 2:
The patent introduces routers as intermediaries that actively monitor link quality and mediate route selection. Instead of end hosts directly detecting and responding to corruption, routers serve as intermediaries that detect corruption on outgoing links and use routing protocols to steer traffic away from problematic paths, reducing retransmission overhead.
3Loss of time
If routers continuously monitor all data packets for corruption, then corrupt links are detected rapidly, but network processing overhead increases significantly
Solution Approach 1:
Routers perform preliminary checksum computation when packets first arrive, storing the results for rapid comparison. This preliminary action eliminates the need for repeated full packet checksumming during routing, enabling fast corruption detection while minimizing ongoing processing energy consumption.
Solution Approach 2:
The system performs full packet checksumming selectively rather than continuously on all packets. Full checksum verification is applied when corruption is detected or suspected, while routine packets use faster partial checking methods, balancing detection speed with energy efficiency.
Data Source
AI summary
A receiving host in a TCP/IP network sends an acknowledgment indicating a received data packet is corrupt. The sending host will begin transmitting with a new field set in the IP header called a check-TCP-checksum bit, thereby requesting that all routers in the TCP/IP network perform a checksum on the entire received packet. Routers in the TCP/IP network will perform a complete checksum on an entire packet with the check-TCP-checksum bit set, and not just on the IP header. The routers continuously monitor the ratio of corrupt packets received on a particular port that fail the entire packet checksum to the total number of packets received on that port. If the ratio of corrupt-to-received packets exceeds a corruption threshold, the router assumes that the associated link is causing data corruption and issues a routing update indicating that the link is bad and should be avoided. Once the retransmission rate between the sender and receiver drops below a threshold level, the bad link has been detected and avoided within the TCP/IP network and the check-TCP-checksum option in the IP header is no longer set in data packets transmitted to the receiver host.