Conditional IPv6 RA

[martin.bernier2]

Hi,

Is there a way to make a router sends RA only under certains conditions ?

For example i would like a router to sends RA only if a specific SLA is true of if the uplink interface (WAN) is UP/UP, etc.

Any ideas ?

Regards,

Martin

[cadet alain]

hi,

maybe with a TCL script or EEM you can disable RA advertisement and reenable it if the sla object is UP but I've never tried it and I don't see any other way of doing this , not even knowing if this is possible like this.

Regards.

Alain

[stmillet]

I think that any design requiring this behaviour is flawed. Can you ellaborate as to the need for this ? What problem are you trying to solve ?

[martin.bernier2]

Thank you everyone,

I agree with you stmillet, this is not a good practice and a routing protocol or HSRP should be used instead.  This is not a real case but i was wondering if there is RA feature that i missed out that could do the trick. 

Ex: 2 internet access with RA enabled ISP routers.  Some ISP doesn't allow HSRP/VRRP and running an IP routing protocol requires an L3 device in the customer network (i'm talking about an ultra low-cost design).  Conditionnal RA could be helpul here isn't ?

Regards,

[Laurent Aubert]

Hi Martin,

RFC4191 brings one piece of the solution but we still need the "tracking part" which I guess will not be standardized.

Thanks,

Laurent.

[martin.bernier2]

Hello,

I just read RFC 6204 about Basic Requirements for IPv6 Customer Edge Routers and it is explicity written:

G-4: By default, an IPv6 CE router that has no default router(s) on

its WAN interface MUST NOT advertise itself as an IPv6 default

router on its LAN interfaces.  That is, the "Router Lifetime"

field is set to zero in all Router Advertisement messages it

originates [RFC4861].

G-5:  By default, if the IPv6 CE router is an advertising router and

loses its IPv6 default router(s) on the WAN interface, it MUST

explicitly invalidate itself as an IPv6 default router on each

of its advertising interfaces by immediately transmitting one

or more Router Advertisement messages with the "Router

Lifetime" field set to zero [RFC4861].

It means putting "ipv6 nd ra-lifetime 0" when WAN is down...

Can someone explain me how it can be achieved ?

Regards,