From: Bajo (bajoalex@gmail.com)
Date: Sat Oct 08 2005 - 13:26:22 GMT-3
According to DocCD: "Only multicast packets with a TTL value greater than
the threshold are forwarded out the interface."
So for ttl=14, anything < or = 14 (less than or equal) will not be
forwarded.
On 10/8/05, Ashok Ananda (aananda) <aananda@cisco.com> wrote:
>
> Hi Chris,
>
> Just want to clarify is this correct for the info mentioned below by
> you:
>
> ~~~~~~~~~~~~~~~~~
> To prevent multicast packets with TTLs less than 15 from being forwarded
>
> Interface fa0/0
> Ip multicast ttl-threshold 14
> ~~~~~~~~~~~~~~~~~
>
> I say config will be
>
> To prevent multicast packets with TTLs less than 15 from being forwarded
>
> Interface fa0/0
> Ip multicast ttl-threshold 13
>
> This is because, TTL less than 15 should not be forwarded means, packets
> with TTL >=14 should be forwarded. My understanding is if I configure
> "Ip multicast ttl-threshold 14" packets with TTL 14 will NOT be
> forwarded.
>
> Correct me if I am wrong.
>
>
> Thanks & Regards,
>
> Ashok M A
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Ralph
> Sent: Wednesday, August 24, 2005 6:20 PM
> To: Chris Lewis (chrlewis)
> Cc: ccielab@groupstudy.com
> Subject: Re: RE: Multicast Filtering
>
> Thanks, Chris.
> Ralph
>
> -----Original Message-----
> From: "Chris Lewis (chrlewis )" <chrlewis@cisco.com>
> To: "Ralph" <Mandela@myrealbox.com>, <ccielab@groupstudy.com>
> Date: Tue, 23 Aug 2005 22:22:34 -0400
> Subject: RE: Multicast Filtering
>
> The following is what I use to remind myself of the options for
> filtering multicast traffic:
>
> If you want to stop certain multicast groups from passing through an
> interface, that is multicast boundary, an example of how to deny
> anything in the 235 range and permit everything else:
>
> Interface fa0/0
> Ip multicast boundary 1 filter-autorp
> !
> Access-list 1 deny 235.0.0.0 <http://235.0.0.0>
0.255.255.255<http://0.255.255.255>Access-list 1 permit
> 224.0.0.0 <http://224.0.0.0> 15.255.255.255 <http://15.255.255.255>
>
> If you want to control which multicast group hosts attached to a router
> interface can join, that is the igmp access-group, shown here for
> 238.1.2.3 <http://238.1.2.3> and the whole 235. range
>
> Interface fa0/0
> Ip igmp access-group 1
> !
> Access-list 1 deny 238.1.2.3 <http://238.1.2.3>
> Access-list 1 deny 235.0.0.0 <http://235.0.0.0>
0.255.255.255<http://0.255.255.255>Access-list 1 permit any
>
> I am not familiar with the igmp profile command, but it looks like that
> it is the 3550 way to accomplish the above, ip igmp profile is not an
> option under interface configuration on a router. The documentation says
> the following:
>
> From the IGMP profile configuration mode, you can specify the parameters
> of the IGMP profile to be used for filtering IGMP join requests from a
> port. Configuration is as below:
>
> Switch # config t
> Switch(config) # ip igmp profile 4
> Switch(config-igmp-profile)# permit
> Switch(config-igmp-profile)# range 229.9.9.0 <http://229.9.9.0>
> Switch(config-igmp-profile)# end Switch(config)# interface
> fastethernet2/12 Switch(config-if)# ip igmp filter 4
>
> To limit which routers can become PIM neighbors (in this case stopping
> neighbor 172.16.15.1 <http://172.16.15.1>)
>
> Interface fa0/0
> Ip pim neighbor-filter 1
>
> Access-list 1 deny 172.16.15.1 <http://172.16.15.1>
> Access-list 1 permit any
>
> To prevent multicast packets with TTLs less than 15 from being forwarded
>
> Interface fa0/0
> Ip multicast ttl-threshold 14
>
> Chris
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Ralph
> Sent: Saturday, August 20, 2005 7:29 PM
> To: ccielab@groupstudy.com
> Subject: Multicast Filtering
>
> Guys:
>
> I'm trying to understand the various ways of filtering multicast
> traffic. I need some assistance with the use of the following multicast
> commands; under what circumstance would some use one instead of the
> other:
>
> 1. ip multicast boundary
> 2. ip igmp access-group
> 3. igmp profile
>
> TIA
> Ralph
>
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-- Kind Regards,Bajo
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