[HN Gopher] The risks and dangers of amplified routing loops
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       The risks and dangers of amplified routing loops
        
       Author : Tiburra
       Score  : 17 points
       Date   : 2021-04-12 08:34 UTC (14 hours ago)
        
 (HTM) web link (toonk.io)
 (TXT) w3m dump (toonk.io)
        
       | SCHiM wrote:
       | This stuff probably wasn't around when IP was designed, but in my
       | own toy routing network protocols I use bloom filters and cuckcoo
       | filters to remove duplicate packets.
       | 
       | Trivial amount of space and computation, easy fix for loop
       | issues. Especially since I assume malicious actors can always
       | connect to any point in my toy network.
       | 
       | I guess the amount of computation required is too much for
       | backbone routers, but for my toy projects it works nice :)
        
         | eqvinox wrote:
         | There's no such thing as a duplicate packet. Older protocols
         | may very well send keepalives as a (UDP) packet that repeatedly
         | has the same contents. Removing/dropping such packets is not
         | something a router is "allowed" to do.
         | 
         | Also, apart from that, all but the smallest routers do not look
         | at the actual data packets. They set up some rules for what
         | they want (i.e. traffic addressed to them, routing protocols,
         | some ICMP, etc.) and everything else never leaves the hardware
         | forwarding pipe. Last I checked, a fat x86 box clocks in at a
         | few 100Gb/s of software forwarding while hardware routers are
         | breaking the 10Tb/s barrier easily.
         | 
         | [Ed. to add:]
         | 
         | Actually, if something further down behind your "deduplicating"
         | router is overloaded/dropping packets, plain TCP will resend
         | the lost packets with little to no changes. If the
         | deduplication drops the retransmits, you've now broken plain
         | current TCP ;). And having dropped packets & retransmits is a
         | fundamental part of how TCP congestion control works (less so
         | with ECN, but still.)
        
       | eqvinox wrote:
       | Feels like an ad piece for <you know who if you read the
       | article>.
       | 
       | Loops in IP routing are a pretty well researched topic and AFAIK
       | practices to avoid them are on most network professional
       | cerficiation exams. Microloops during convergence are even an
       | active topic of research.
       | 
       | Also, just to be clear, a loop can only bring down systems
       | involved in it, you can't use it as a "packet accelerator".
       | (Unless something is _seriously_ borked, or you have a multicast
       | loop.)
        
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       (page generated 2021-04-12 23:01 UTC)