[Planetlab-devel] Re: [PL #45504] VSYS script for adjusting txqueuelen parameter on tap interface

[Thom Haddow]

Sapan Bhatia wrote:
> Hi Thom,
> 
> I didn't run into that problem because I didn't try using the interface 
> or bringing it down. I've updated the code with your change. As for the 
> issue of the client process hanging, I agree, we can eliminate vif_down 
> and make closing the fd the only means of bringing down the tap 
> interface. Now there's only the issue of garbage-collecting the iptables 
> rules that protect these interfaces so that they don't grow out of 
> bounds. I'm thinking that we might want to use a single rule and do a 
> prefix match on the device (I just discovered that if you add a '+' 
> before the interface name, then it is recognized as a prefix.) 

The vif_up script attempts to remove any existing rules before creating new
ones, so the worst case scenario is two rules per interface name per slice, and
the interface names are recycled between uses. I don't think this would be too 
bad, given the limited appeal of such functionality.

cheers,

Thom