[neutron][queens] dhcp issue

Ignazio Cassano ignaziocassano at gmail.com
Wed Dec 11 17:36:16 UTC 2019

Hello Jeremy, thanks for your help.
Indeed when more subnet of a provider vlan are created, instance on one of
the subnet receives the static routes of all subnets.
Is it correct?

Il Mer 11 Dic 2019, 16:29 Jeremy Stanley <fungi at yuggoth.org> ha scritto:

> On 2019-12-11 10:10:17 +0100 (+0100), Ignazio Cassano wrote:
> [...]
> > Dec 11 09:49:06 podto2-osctrl01 dnsmasq-dhcp[70093]: cannot send
> >     DHCP/BOOTP option 121: no space left in packet
> [...]
> This error is fairly straightforward. DHCP replies are limited to
> what you can fit in a single UDP packet and how large of a datagram
> the client agrees to accept. The number of routes you're trying to
> include in via option 121 could be the problem (is it a bunch?) but
> also the other fields and their lengths can also contribute, as can
> the MTU on that network segment:
>     https://tools.ietf.org/html/rfc2131
> According to IETF RFC 2131 you should be able to assume clients will
> accept a datagram of up to 576 octets in length (which implies your
> entire options field can use at least 312 octets). Anything over
> this requires negotiation of a maximum DHCP message size with the
> client.
> --
> Jeremy Stanley
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