Charter ARP Leak
rbf at rbfnet.com
Mon Dec 29 17:35:42 UTC 2014
On Mon, Dec 29, 2014 at 12:27:04PM -0500, Jay Ashworth wrote:
> > Valdis, you are correct. What your seeing is caused by multiple IP
> > blocks being assigned to the same CMTS interface.
> Am I incorrect, though, in believing that ARP packets should only be visible
> within a broadcast domain,
broadcast domain != subnet
> and that because of that, they should not be
> being passed through a cablemodem attached to such a CMTS interface unless
> they're within the IP network in which that interface lives (which is
> probably not 0/0)?
> This sounds like a firmware bug in either the CMTS or the cablemodem.
int ethernet 0/0
ip address 10.0.0.1 255.255.0.0
ip address 126.96.36.199 255.255.0.0 secondary
ip address 188.8.131.52 255.255.0.0 secondary
The broadcast domain will have ARP broadcasts for all three subnets.
Doing it over a CMTS doesn't change that.
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