ASA 5506 firewall DHCP6 will not get global address from Spectrum

I have a Cisco ASA5506 firewall connected to my ARRIS SB6190 cable modem and it will not pick up an IPV6 global address.  I connect my TPlink router to the SB6190 and turn on IPV6 and it works fine.   if I plug the ASA firewall into the TPlink router it gets a IPV6 address ok.   If I plug a Windows laptop into the cable modem it works fine with IPV6..    IPv4 works fine on the ASA.


why does the Cisco ASA 5506 not work with the Spectrum Internet?  


current outside interface config and status below.


interface GigabitEthernet1/1
nameif outside
security-level 0
ip address dhcp setroute
ipv6 address dhcp default
ipv6 enable
ipv6 nd reachable-time 3600000
ipv6 nd suppress-ra
ipv6 dhcp client pd hint ::/56
ipv6 dhcp client pd tw-pfx


#sho  IPV6 interface outside


outside is up, line protocol is up
IPv6 is enabled, link-local address is fe80::1a80:90ff:fee8:d361
No global unicast address is configured
Joined group address(es):
ICMP error messages limited to one every 100 milliseconds
ICMP redirects are enabled
ND DAD is enabled, number of DAD attempts: 1
ND reachable time is 3600000 milliseconds
Hosts use stateless autoconfig for addresses.


# sho ipv6 router

Router fe80::201:5cff:fe8b:e646 on outside, last update 0 min
Hops 0, Lifetime 1800 sec, AddrFlag=1, OtherFlag=1
Reachable time 3600000 msec, Retransmit time 0 msec






Re: ASA 5506 firewall DHCP6 will not get global address from Spectrum

TWC never got the bugs out of IPv6, Spectrum has made it even worst. 

Solution is to turn off IPv6, sorry....  Isuue is their horribly lagging path thru numerous overloaded path to a single IPv6 DNS box at one NOC whereas IPv4 is at several RDC's


State your location and paste an IPv4 tracert to

and another via IPv6 to the at  dns


I've seen it go 3 seconds on Ipv4 and 10-30 seconds on Ipv6.

If you can find a way to bypass the timeout timer you may get Ipv6 to work. Spectrum knows there's an issue and is providing business class customers with seperate emta phone only modems then an Ipv6 Ubee combo modem router with wireless.. no all in ones , the emta phone will not work with IPv6 and it shoots down the IPv4 as well in those.




Re: ASA 5506 firewall DHCP6 will not get global address from Spectrum

This was working up until a few weeks ago, with pretty much the same config as you, and then abruptly quit working.


It's because the DHCPv6 response coming back from Spectrum has a hop-count of zero, which is invalid, and which the ASA drops (correctly) but some other routers allow (incorrectly).  I verified this by running tcpdump between the ASA and the cable modem (by inserting a switch w/ a span port).


Some Comcast head-ends are/were doing the same thing (google "comcast dhcpv6 pd hop count 0") for quite some time.