Cable Connection drops when IPv6 activated (Cisco ASA 5500 Series)

According to Time Warner (or Spectrum as they are now called), they are ready for IPv6: https://www.timewarnercable.com/en/support/internet/topics/ipv6.html, at least for customers that have dynamically assigned IP addresses.

And sure enough, if a computer is directly to the modem, the computer is assigned an IPv6 address in addition to an IPv4 address.

However, when IPv6 is activated on the Cisco ASA 5500 series:

interface vlan2  !--- my 'outside' interface
    ipv6 enable

Communication from the service provider's modem to the ASA promptly ceases (i.e. IPv4 connectivity is lost as well).

If the following configuration change is made:

interface vlan2
    no ipv6 enable

IPv4 connectivity resumes.

Obviously the ASA has plenty of options for configuring IPv6. Perhaps there is something missing? Perhaps the service provider has a draconian filtering policy?

Has anyone had any experience getting IPv6 to work with cable internet service providers? Did they have to do anything special?

xirt

Posted 2017-02-09T05:23:06.403

Reputation: 149

Answers

It appears that adding the following command seems to resolve the issue:

interface vlan2
    ipv6 nd suppress-ra

Presumably the service provider is black-holing traffic when they see an IPv6 route announcement as an incentive to discourage people from advertising their subnets.

xirt

Posted 2017-02-09T05:23:06.403

Reputation: 149

1I was going to explain to you that residential networking is handled differently at Spectrum, and you cannot try to route back to them. I learned this the hard way when IPv6 was first supported by TWC. It really has nothing to do with Cisco, but the residential network doesn't allow you to do what would be commonplace in a business. Spectrum really ignores RFC 6177, and the residential support still thinks you only get a single address, even on IPv6, even though you (only) get a /64 network. – Ron Maupin – 2017-02-09T05:33:21.623