From: Carlos G Mendioroz (tron@xxxxxxxxxxx)
Date: Thu May 16 2002 - 07:18:10 GMT-3
Hi,
I think that directed-broadcast will affect the router "exploding" the
directed
broadcast at the destination network (i.e. its sending to the broadcast
mac)
and not its forwarding of them.
The distinction is important. It's not enough to turn it off at the
borders,
you have to turn it off in every interface at every router...
David Luu wrote:
>
> a broadcast address is 255.255.255.255
> a directed broadcast address is, for example on the 192.168.1.0/24 subnet,
> 192.168.1.255
>
> a router will forward directed broadcast if it has a route to the subnet
> and does not block them by default on IOS' prior to 12.0
>
> > -----Original Message-----
> > From: Tom Young [mailto:gitsyoung@yahoo.co.jp]
> > Sent: Thursday, 16 May 2002 11:33
> > To: Jason Sinclair
> > Subject: RE: some command
> >
> > Jason:
> > Thank you for your reply, I understood the two command
> > now.
> > But I still don't know their function, for example,
> > route couldn't forward any broadcast, it is the rule of
> > router, so I think the router couldn't forward the
> > 192.168.1.255,basicly. So, the no ip directed-broadcast is
> > meanless.
> > And the mroute-cache, if the router don't cache the
> > unicast route, It will take more longer time for
> > forwarding packet. Why do so? Has it some advantage?
> >
> > Sorry for asking you so simple question, and take your
> > time.
> >
> > Best regards
> >
> > Young
> >
> > --- Jason Sinclair <sinclairj@powertel.com.au> ????
> > ?????
> > > Tom,
> > >
> > > Let's start with no ip directed-broadcast:
> > > This instructs the router to not forward packets
> > > that are destined
> > > to a directed broadcast address. For example, a
> > > broadcast is 255.255.255.255
> > > in IP terms. In the case of 192.168.1.0/24, the
> > > directed broadcast address
> > > is 192.168.1.255. Hence the router will not
> > > propagate packets to this
> > > address.
> > >
> > > Now for no ip mroute-cache:
> > > This instructs the router to turn off cache support
> > > for multicast
> > > packets. Basically is the same as turning off
> > > route-cache for unicast
> > > packets and instructs the router to process switch
> > > multicast packets.
> > >
> > > Regards,
> > >
> > > Jason Sinclair CCIE #9100
> > > Manager, Network Control Centre
> > > POWERTEL
> > > Ground Level, 55 Clarence Street,
> > > SYDNEY NSW 2000
> > > AUSTRALIA
> > > office: + 61 2 8264 3820
> > > mobile: + 61 416 105 858
> > > * sinclairj@powertel.com.au
> > >
> > >
> > >
> > >
> > >
> > > -----Original Message-----
> > > From: Tom Young [mailto:gitsyoung@yahoo.co.jp]
> > > Sent: Thursday, 16 May 2002 10:41
> > > To: ccielab@groupstudy.com
> > > Subject: some command
> > >
> > > For some simple command, I couldn't find the
> > > explain from
> > > CCO, who can exlain it to me precisely?
> > > For example:
> > >
> > > no ip directed-broadcast
> > > and
> > > no mroute-cache
> > >
> > >
> > > Thanks
> > >
> > > Young
> > >
This archive was generated by hypermail 2.1.4 : Thu Jun 13 2002 - 10:58:58 GMT-3