[Dnsmasq-discuss] dnsmasq, no RA being sent after RTR solicitation when interface has /128 prefix assigned

[Christof Schulze]

Hello everyone,

This is my first post to this list.
Recently I have observed that dnsmasq sending Ras seems to depend on the 
ipv6 address that is assigned to the interface that dnsmasq is running 
on. This is a discrepancy to what uradvd is doing. Do I have a 
configuration issue or is this a missing feature and/or bug in dnsmasq?

This is my setup:
========================================================
dnsmasq.conf

domain-needed
localise-queries
read-ethers
expand-hosts
cache-size=5000
domain=client
server=/lan/
server=2a06:8187:fb00:53::53
dhcp-leasefile=/tmp/dhcp.leases
resolv-file=/tmp/resolv.conf.auto
addn-hosts=/tmp/hosts
user=dnsmasq
group=dnsmasq

enable-ra
dhcp-range=2a06:8187:fbab:0002::,ra-stateless,64,1h
dhcp-option=option6:dns-server,[2a06:8187:fbab:2::1]

interface=local-node

no-dhcp-interface=br-wan
========================================================


When the local-node interface is set up like this, then there will be RAs sent by dnsmasq
9: local-node at local-port: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 16:41:95:40:f7:dc brd ff:ff:ff:ff:ff:ff
    inet 10.126.0.1/16 brd 10.126.255.255 scope global local-node
       valid_lft forever preferred_lft forever
    inet6 2a06:8187:fbab:2:15::1/64 scope global 
       valid_lft forever preferred_lft forever
    inet6 2a06:8187:fbab:2::1/128 scope global deprecated 
       valid_lft forever preferred_lft 0sec
    inet6 fe80::1441:95ff:fe40:f7dc/64 scope link 
       valid_lft forever preferred_lft forever

While when local-node is set up like this, there will not be any RA sent by dnsmasq:
9: local-node at local-port: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 16:41:95:40:f7:dc brd ff:ff:ff:ff:ff:ff
    inet 10.126.0.1/16 brd 10.126.255.255 scope global local-node
       valid_lft forever preferred_lft forever
    inet6 2a06:8187:fbab:2::1/128 scope global deprecated 
       valid_lft forever preferred_lft 0sec
    inet6 fe80::1441:95ff:fe40:f7dc/64 scope link 
       valid_lft forever preferred_lft forever

I would appreciate insights into how I could get dnsmasq to send Ras even in
the second scenario, withouth the additional /64 address.

Regards

Christof
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