[Kea-users] DHCPOFFER delay

[Andrey Kostin]

Hi Darren,

Thank you for your reply. You're correct, if one router dies, dhcp 
clients will experience an outage until rebind, but this time is 
relatively short because of asymmetric lease feature (also called lease 
split) with short lease time. These users aren't in a common broadcast 
domain, they are broadband customers and connected in individual S-C 
vlans that are terminated on dynamically created subinterfaces only on 
one of routers. If they get IPs from the same subnet, we would have to 
advertise individual IPs from each router to direct traffic destined to 
subscriber's IP to a correct router.
Delay manipulation I asked for comes from PPPoE where subscribers 
connections can be directed to more preferred router. Actually Juniper 
has implemented this feature for it's local dhcp server, but not for the 
relay:
https://www.juniper.net/documentation/us/en/software/junos/subscriber-mgmt-sessions/topics/topic-map/dhcp-local-server-response-delay.html

No problem though, it's not the end of the world to not have this delay.
Another quick question, what's the recommended way to stop serving users 
from a subnet/pool? For example, there is a shared network with a subnet 
and this subnet has a pool and no static reservations. Which way is 
better, to comment out "pools":, comment out "subnet4" section or delete 
whole shared-network to make dhcp clients switch to another 
relay/subnet, considering that it's available via another relay?

Kind regards,
Andrey

Darren Ankney писал(а) 2024-11-08 16:41:
> Hi Andrey,
> 
> I cannot think of a way to accomplish this.  The usual way things like
> this are done is that the same subnet is assigned to both relays.  The
> client is given a gateway address that is a floating IP between the
> two relays (which are also the gateway routers).  In this way, it
> doesn't matter which relay sends the traffic to the DHCP server.  The
> correct subnet is allocated and routing works.  It sounds like, in
> this case, you've assigned separate subnets to the relays ... Kea
> won't even know that they are related in any way.  Won't this cause a
> temporary customer routing problem if one of the routers dies?
> 
> Thank you,
> Darren Ankney
>