[Cake] Playing with ingredients = ruined the CAKE

Kevin Darbyshire-Bryant kevin at darbyshire-bryant.me.uk
Fri May 29 06:06:50 EDT 2020

I’m trying to create a ‘diffserv5’ for the purposes of implementing a 'Least Effort’ class: something like LE=Bittorrent, BK=Backups/long term down/uploads, BE=Best Effort/Normal, VI=Streaming media/facetime/zoom, VO=VOIP/SIP.  Not too hard you’d think, take diffserv4 and add a tin.

I did this with tin allocation: 0=LE, 1=BE, 2=BK, 3=VI, 4=VO.  BW allocation relative to base rate = LE>>8, BE>>0, BK>>4, VI>>1, VO>>2.  Tin display order = 0, 2, 1, 3, 4.  In theory I don’t mind LE being starved hence the above order.  This pretty much ‘jammed' the shaper as soon as any traffic went into LE with other higher priority tins seeing huge latencies, lots of drops and general bad news all over.

I tried again with a slightly different tin allocation: 0=BE, 1=LE, 2=BK, 3=VI, 4=VO more in keeping with the existing arrangement and display order 1, 2, 0, 3, 4. The shaper doesn’t appear to obviously wedge, though I have seen some latency spikes that I don’t normally see, so it feels like there’s still a corner case being hit.

Does anyone have any ideas?


Kevin D-B

gpg: 012C ACB2 28C6 C53E 9775  9123 B3A2 389B 9DE2 334A

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