# Interim IDONTWANT bandwidth sim report

- ran six sims:
- 3/6 blobs, 0% IDONTWANT compatible nodes: 16.1 KiB/s
- 3/6 blobs, 20% IDONTWANT (comparable to mainnet's ~15%): 17.7 KiB/s
- 3/6 blobs, 100% IDONTWANT: 18.3 KiB/s
- 4/8 blobs, 0% IDONTWANT: 19.4 KiB/s
- 4/8 blobs, 20% IDONTWANT: 20.8 KiB/s
- 4/8 blobs, 100% IDONTWANT: 21.6 KiB/s
- bandwidth suspiciously low, are blobs snappy compressed or truncated on wire if remaining bytes are 0? will try to fix
- IDONTWANT seems to **RAISE** bandwidth requirements?
- *Quadruple* checked that I didn't flip a condition or mislabled the simulations and then investigated:
- Issue A: We send out IDONTWANT pretty early, before most validation. IRL, this means we do this before spending ~5ms validating the blob. In the simulation, the validation takes ~0ms (compare [this shadow feature request](https://github.com/shadow/shadow/issues/2060)), so blobs propagate more quickly, leaving less opportunity to receive a IDONTWANT before validation finishes. Therefore, we dont save bandwidth.
- Issue B: Shadow does not support network latency jitter, and my current network topology does not make a difference between nodes in a region/reliability. This means that if a node in Europe sends a message to all peers, the message will arrive at the exact same time for nodes in the same region/reliability: after 70ms in US East, 110ms in US West, etc.. So nodes in the same region will never have the opportunity to receive an IDONTWANT from nodes in the same region, as they process the message exactly simultaneously, and instantly (see issue A).
- Quick fix:
- add 5ms artificial delay to blob sidecar verification
- drop intra-region latency low enough so that some IDONTWANTs will be received before the above 5ms
- of course this is not ideal and shows the IMO biggest weakness of shadow right now: infinitely fast computations
- sims running right now, new results Soon :soon::tm:
- Good fix:
- add support for capturing computation time to shadow: complex, likely no time for that :(
- add support for network jitter to shadow: probably harder than it sounds
- make network topology more complex so that latencies are more uneven: should be possible