I2C port pins are supposed to have internal filtering or blanking or slew rate limiting as it is. If not, well...
50ns blanking corresponds to about 5-10MHz analog bandwidth, which is a good precaution for lengthy digital routes.
If you're routing I2C over cables, don't even bother unless you're prepared to:
- Avoid high speed mode.
- Short lengths (under 30cm, say): use ribbon cable or better, every other line GND or VCC (doesn't matter as long as they're bypassed at each connector). On the signal (both SCL and SDA), use ~300 ohm ferrite bead and 470pF cap at each end to filter RFI.
- Medium lengths (few m): use shielded multiconductor cable, same filtering as above (or even more C, or with R+C in parallel with C to dampen resonances). Shield goes directly to circuit ground at each end.
- Long lengths (more than, say, 5m): forget about it. If you insist, use an I2C extender interface chip, and something differential (usually RS422/485).
I2C is precisely what it is: a standard to use between ICs on a single PCB, or at most, a couple connected together on stacking headers, or short ribbon cables. It is not at all robust to noise, making it very impractical over distances.
Tim