Setting the "other-config-flag" or O-bit on a Cisco ASA

Frank Bulk - frnkblk at
Thu Mar 24 19:39:34 CET 2011

Good point.  But changing a customer's network topology to get IPv6 support
is not a winning approach.  Hopefully Cisco can surprise us and get that
feature put in earlier rather than later.  We have quite a few customers
that use a small ASA their edge network device.


-----Original Message-----
From: Dale W. Carder [mailto:dwcarder at]
Sent: Thursday, March 24, 2011 9:26 AM
To: Eric Vyncke (evyncke)
Cc: frnkblk at; ipv6-ops at
Subject: Re: Setting the "other-config-flag" or O-bit on a Cisco ASA

Another option you may be able to consider is to run the ASA in transparent
mode and letting the router route.  This depends on your topology, of


Thus spake Eric Vyncke (evyncke) (evyncke at on Thu, Mar 24, 2011 at
02:52:37PM +0100:
> Frank,
> I am afraid that there is currently no way for ASA to set the O-bit (or
even the M-bit or the router priority)...
> Next version (end of this year) should have those needed features...
> Some customers are using a Linux box to send RA with the O-bit
information, same prefix and low priority
> -?ric
> > -----Original Message-----
> > From: at
> > at] On Behalf Of Frank Bulk
> > Sent: jeudi 24 mars 2011 14:39
> > To: ipv6-ops at
> > Subject: Setting the "other-config-flag" or O-bit on a Cisco ASA
> >
> > We have customers that use an ASA and would like to use stateless DHCPv6
> > their Windows 2008 server to get the DNSv6 servers.  I don't see "ipv6
> > other-config-flag" on our ASA nor in the documentation.  How do people
> > this off?
> >
> > Frank

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