From: Mohammad Ishaq (netcon@myrealbox.com)
Date: Sat Jan 10 2004 - 12:07:03 GMT-3
Another query which I'm hopeing someone can answer and that is why is there
a specific deny "deny udy any any" in the access-list given in the Cisco
Sample? Surely then is a implicit deny any any at the end of all
access-lists.
access-list 120 permit udp any any 4000
access-list 120 deny udp any any
ip forward-protocol udp 4000
Thanks in advance
Mohammad
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Pun,
Alec CL
Sent: 19 December 2003 06:45
To: Brian McGahan; 'Lord, Chris'; ccielab@groupstudy.com
Subject: RE: multicast helper map
Hi Brian,
Agree with your previous posts. But some further questions on the DocCD
example:
A) How about PIM-dense mode ? I think it is necessary on interface "1" and
"2" but "3" is not required.
B) I think the ip directed-broadcast command is ONLY necessry on interface
"3" as it is the only place whether directed broadcast is translated to
physical broadcast
C) In the DocCD, it mentioned "On the last hop router, the ip multicast
helper-map interface configuration command automatically introduces ip igmp
join-group group-address on that interface. This command must stay on that
interface for the intermediate IP multicast helper feature to work. If you
remove the ip igmp join-group command, the feature will fail. "
However, I don't see this command was automatically added after added the
helper-map command. Should I add it manually afterwards ?
rgds,
alec
-----Original Message-----
From: Brian McGahan [mailto:bmcgahan@internetworkexpert.com]
Sent: Saturday, December 06, 2003 1:25 AM
To: 'Lord, Chris'; ccielab@groupstudy.com
Subject: RE: multicast helper map
Chris,
The helper map needs to be configured on the first hop router and
the last hop router. The first hop is where the broadcast stream gets
converted from a broadcast to a multicast. The last hop is where the
multicast gets converted back into a broadcast.
_____
| ( ) |
|--R1--( Mcast )--R2--|
| ^ (_____) ^ ^ |
1 2 3
The source of the broadcast feed is located on R1's interface "1".
This is the incoming interface for the broadcast stream. The destination
the traffic is trying to get transported to is on R2's interface "3". The
incoming interface for the multicast stream is R2's interface "2" which
connects to the multicast cloud. The confusion in the documentation CD
example is that this incoming interface "2" is an Ethernet interface. When
you look at the example at a glance it looks like they're referring to
interface "3" when they are actually referring to "2".
The following configuration should go on interface "1"
ip multicast helper-map broadcast 225.5.5.5 100
where 255.5.5.5 is the multicast address to convert the broadcast to as
"100" is an extended access-list that matches the traffic to convert.
The following configuration should go on interface "2"
ip multicast helper-map 225.5.5.5 12.255.255.255 100
where 255.5.5.5 is the same group as previously referenced, 12.255.255.255
is the directed broadcast address of interface "3", and access-list 100 is
the same as previously referenced.
HTH,
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987
Direct: 708-362-1418 (Outside the US and Canada)
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Lord, Chris
> Sent: Friday, December 05, 2003 7:38 AM
> To: ccielab@groupstudy.com
> Subject: multicast helper map
>
> Hi Group,
>
> Please can anybody help me with this one? The Doc CD for the multicast
> helper map command contains the following lines on the ethernet port of
> the last hop router:
>
> ip directed-broadcast
> ip broadcast-address 178.21.34.255
> ip multicast helper-map 224.5.5.5 178.21.34.255 120
>
> This assumes that the multicast receipients are physically located on the
> same lan as the local interface. How would the commands above have to be
> changed if the receipients were located on a different subnet 1 or more
> hops away (say 192.168.5.0/24)?
>
> Thx in anticipation,
>
> Chris.
>
>
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