From: Nguyen, Thai (Thai.Nguyen@xxxxxxxxxxxxxx)
Date: Thu May 16 2002 - 03:59:20 GMT-3
Hi,
It appears that it is not desirable to have directed broadcast on, unless we
have to.
Can you one give an example when we have to enable it.
Thanks
-----Original Message-----
From: David Luu [mailto:wicked01@ix.netcom.com]
Sent: Thursday, May 16, 2002 1:57 PM
To: Jason Sinclair; 'Tom Young'
Cc: 'ccielab@groupstudy.com'
Subject: RE: some command
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
> >
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