IPV6 default route disappearing

Post new topic   Reply to topic    DD-WRT Forum Forum Index -> Atheros WiSOC based Hardware
Author Message
MV_ddwrt19
DD-WRT Novice


Joined: 23 Feb 2019
Posts: 10

PostPosted: Sat Feb 23, 2019 19:55    Post subject: IPV6 default route disappearing Reply with quote
Hi all,

can someone please help with the IPV6 issue I'm having. My config:
R7800 with Firmware: DD-WRT v3.0-r38835M kongat (02/18/19)

I've enabled IPV6:
Setup-IPV6: IPVT enable, DHCPv6 with Prefix Delegation
Prefix length: 64
DNSs both blank
MTU default 1452
Dhcp6c custom, Dhcp6s, Radvd - disabled

Services-Dnsmasq:
Dnsmasq - enabled
Cache DNSSEC data - disabled
Validate DNS Replies (DNSSEC) - disabled
Check unsigned DNS replies - disabled
Local DNS - enabled
No DNS Rebind - enabled
Query DNS in Strict Order - enabled
Add Requestor MAC to DNS Query - disabled

Additional Dnsmasq Options:
local=/local/
expand-hosts
server=2606:4700:4700::1111
server=2606:4700:4700::1001
interface=br0
dhcp-range=::1000,::FFFF,constructor:br0,ra-stateless,12h
dhcp-option=option6:dns-server,[::]
ra-param=br0,10,300
enable-ra

This config get the router and devices on my LAN IPV6 addresses. IPV6 test sites all test ok but in a few minutes the same IPV6 test site report no IPV6 support.

After some research, i found this site: https://rsalveti.wordpress.com/2016/07/27/netgear-r7000-dd-wrt-ipv6-and-the-lack-of-a-stable-gateway/
that talks about this exact behaviour.

So, I SSH and check ip -6 route and when IPV6 is working I see that the default route is there:
default via fe80::29e:1eff:fe59:9022 dev eth0 metric 1024 expires 170sec

But then, in a few minutes the default route drops and ip -6 route becomes this:
2601:586:c403:1722::/64 dev br0 metric 256
fe80::/64 dev br0 metric 256
fe80::/64 dev eth1 metric 256
fe80::/64 dev ath0 metric 256
fe80::/64 dev ath1 metric 256
fe80::/64 dev ath1.1 metric 256
fe80::/64 dev eth0 metric 256
unreachable default dev lo metric -1 error -101
ff00::/8 dev br0 metric 256
ff00::/8 dev eth1 metric 256
ff00::/8 dev ath0 metric 256
ff00::/8 dev ath1 metric 256
ff00::/8 dev ath1.1 metric 256
ff00::/8 dev eth0 metric 256
unreachable default dev lo metric -1 error -101

From the site I mentioned, I run this to determine if my ISP (Comcast) broadcasts the default route:
tcpdump -vvvv -ttt -i eth0 icmp6 and 'ip6[40] >= 133 && ip6[40] <= 134'

which in a second comes up with this:
00:00:03.132041 IP6 (class 0xe0, hlim 255, next-header ICMPv6 (5Cool payload length: 160) fe80::29e:1eff:fe59:9022 > ff02::1: [icmp6 sum ok] ICMP6, router advertisement, length 160
hop limit 64, Flags [managed, other stateful], pref medium, router lifetime 1800s, reachable time 3600000s, retrans time 0s
source link-address option (1), length 8 (1): 00:9e:1e:59:90:22
0x0000: 009e 1e59 9022
mtu option (5), length 8 (1): 1500
0x0000: 0000 0000 05dc
prefix info option (3), length 32 (4): 2001:558:40c0:80::/64, Flags [none], valid time 604800s, pref. time 302400s
0x0000: 4000 0009 3a80 0004 9d40 0000 0000 2001
0x0010: 0558 40c0 0080 0000 0000 0000 0000
prefix info option (3), length 32 (4): 2001:558:5014:84::/64, Flags [none], valid time 604800s, pref. time 302400s
0x0000: 4000 0009 3a80 0004 9d40 0000 0000 2001
0x0010: 0558 5014 0084 0000 0000 0000 0000
prefix info option (3), length 32 (4): 2001:558:6030:7a::/64, Flags [none], valid time 604800s, pref. time 302400s
0x0000: 4000 0009 3a80 0004 9d40 0000 0000 2001
0x0010: 0558 6030 007a 0000 0000 0000 0000
prefix info option (3), length 32 (4): 2001:558:801e:88::/64, Flags [none], valid time 604800s, pref. time 302400s
0x0000: 4000 0009 3a80 0004 9d40 0000 0000 2001
0x0010: 0558 801e 0088 0000 0000 0000 0000

So, the broadcast is there! Also, as soon as I run this command, the default route re-appears in ip -6 route and IPV6 works again. But, after a few minutes stops.

For now, I added the default route manually but that's not a good solution as its IP might change.

Can anyone help determining why the IPV6 default route drops?
Sponsor
MV_ddwrt19
DD-WRT Novice


Joined: 23 Feb 2019
Posts: 10

PostPosted: Fri Mar 29, 2019 1:02    Post subject: Reply with quote
All needed for this issue to be resolved was to disable (uncheck) "Filter Multicast" on Security/Firewall page
mac913
DD-WRT Guru


Joined: 02 May 2008
Posts: 1405
Location: Canada

PostPosted: Fri Mar 29, 2019 1:40    Post subject: Reply with quote
Incase IPv6 stops working...

I ran into the same problem,read my Post...
https://forum.dd-wrt.com/phpBB2/viewtopic.php?p=1158692&highlight=r7800+rdisc6#1158692

More likely you need the "rdisc6" file, like the site you found, read the whole article again. I have attached the file just unzip it.

Since the article was written for an R7000 the WAN port is vlan2. My cron runs every 15min on the R7800...

*/15 * * * * root /your-directory/rdisc6 -1 -q eth0

_________________
Home Network on Telus PureFibre - 10GbE Copper Backbone
2x R7800 - Gateway WiFi 3xVPN - KONGAT 39855M
E3000 - Gateway Wired IPTV - DDWRT r35531 Mega
WHR-HP-G54 - Internal Routing - DDWRT r35531 std-special

______________________
Off Site 1

R7000 - Gateway & WiFi & VPN - KONGAC 39855M
WRT610Nv1 - Repeater Bridge - DDWRT r33679 Mega K2.4

__________________________
Off Site 2

2x R7000 - Data Gateway, WiFi & IPTV WiFi, PVR Blocker- KONGAC 39855M

__________________
YAMon 3.4 | Ad-Blocking for DD-WRT | DNSCrypt-Proxy V2
stalonge
DD-WRT Guru


Joined: 21 Jul 2006
Posts: 1910
Location: Fortaleza Ce Brazil

PostPosted: Fri Mar 29, 2019 22:44    Post subject: Reply with quote
MV_ddwrt19 wrote:
All needed for this issue to be resolved was to disable (uncheck) "Filter Multicast" on Security/Firewall page


Thanks

you turn darkness to light

Very Happy Very Happy

_________________
DDwrt ...it rocks ....
1 R8500 41526 K AP openVPN & webserver
1 R7800 41526 AP Wireguard webserver JFFS SAMBA FTP usb HD Mesh
1 R7800 40270 Kong Cli Mesh
1 WZR1750 41468 AP
1 DDx86 Vmware 40260
1 E3000 41027 K3 @500 WAP wifi client
Display posts from previous:    Page 1 of 1
Post new topic   Reply to topic    DD-WRT Forum Forum Index -> Atheros WiSOC based Hardware All times are GMT

Navigation

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You cannot download files in this forum