[SOLVED] IPv6 Router Advertisement delay.

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nullbyte
Posts: 4
Joined: 19 Nov 2020, 13:08

[SOLVED] IPv6 Router Advertisement delay.

Post by nullbyte »

Hi There,

I have a dual stack IPv4/IPv6 PPPoE setup, serving connectivity to DSL CPEs.

IPv4 is fine. IPv6 is fine too, but if the CPE gets disconnected, or if I restart the accel-ppp instance, hence the ppp link is broken, the CPE
will take time (3 to 10 minutes) before getting it's default route back to the ppp server.

I believe this is caused by router advertisement being send too slowly (up to 9 minutes before sending a new rouler advertisement packet), see below:

accel-ppp conf (snip, only relevant config):

Code: Select all

[modules]                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
log_file                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      
pppoe                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
auth_pap                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               
ippool                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
chap-secrets                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
ipv6pool                                                                                                                                                                                                                                                                                                                                                                                                                                                      
ipv6_nd                                                                                                                                                                                                                                                                  
ipv6_dhcp 

[ppp]                                                                                                                                                                                                                                                                    
#show verbose authentifaction                                                                                                                                                                                                                                            
verbose=1                                                                                                                                                                                                                                                                
min-mtu=1230                                                                                                                                                                                                                                                             
mtu=1492                                                                                                                                                                                                                                                                 
mru=1492                                                                                                                                                                                                                                                                 
ipv4=require
ipv6=allow
(snip)

[ipv6-pool]
#pool for ppp
2a02:a03f:1601:4000::/52,64
#pool for LAN
delegate=2a02:a03f:17ff::/48,52

[ipv6-dhcp]
verbose=1
ppp0 configuration:

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11: ppp0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1492 qdisc pfifo_fast state UNKNOWN group default qlen 3
    link/ppp 
    inet 10.67.15.1 peer 10.67.15.2/32 scope global ppp0
       valid_lft forever preferred_lft forever
    inet6 2a02:a03f:1601:4000:100::/64 scope global nodad 
       valid_lft forever preferred_lft forever
    inet6 fe80::100:0:0:0/64 scope link 
       valid_lft forever preferred_lft forever
tcpdump -enni physcpe

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12:55:48.733809 Out ethertype IPv6 (0x86dd), length 104: fe80::100:0:0:0 > ff02::1: ICMP6, router advertisement, length 48
...
13:04:48.734880 Out ethertype IPv6 (0x86dd), length 104: fe80::100:0:0:0 > ff02::1: ICMP6, router advertisement, length 48
...
13:08:17.735691 Out ethertype IPv6 (0x86dd), length 104: fe80::100:0:0:0 > ff02::1: ICMP6, router advertisement, length 48
...
13:14:45.736466 Out ethertype IPv6 (0x86dd), length 104: fe80::100:0:0:0 > ff02::1: ICMP6, router advertisement, length 48
Is there a way to decrease the "Router Advertisement" interval to be more aggressive ?

Thank you very much,

Regards,
Last edited by nullbyte on 24 Nov 2020, 08:16, edited 1 time in total.
dimka88
Posts: 866
Joined: 13 Oct 2014, 05:51
Contact:

Re: IPv6 Router Advertisement delay.

Post by dimka88 »

Hello nullbyte, I think you need to change the following params

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[ipv6-dhcp]
verbose=1
pref-lifetime=n
valid-lifetime=n
nullbyte
Posts: 4
Joined: 19 Nov 2020, 13:08

Re: IPv6 Router Advertisement delay.

Post by nullbyte »

Hi @dimka88

Found the solution :)
Posting here the solution for documentation and maybe help other people :)

Code: Select all

[ipv6-nd]
verbose=1
AdvDefaultLifetime=300 # Advertise a default lifetime of 5m.
MaxRtrAdvInterval=30 # Sent router advertisement at most every 30s
dimka88
Posts: 866
Joined: 13 Oct 2014, 05:51
Contact:

Re: [SOLVED] IPv6 Router Advertisement delay.

Post by dimka88 »

Hi @nullbyte, was added some ipv6-nd options to docs https://accel-ppp.readthedocs.io/en/lat ... v6-nd.html
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