From: A (anil_raksha@rediffmail.com)
Date: Wed Jun 22 2005 - 03:36:54 GMT-3
Hi all,
This command and the ip pim neighbor-filter command together enable
stub multicast routing. The IGMP host reports and leave messages are forwarded
to the IP address specified. The reports are re-sent out the next hop
interface toward the IP address, with the source address of that interface.
This command enables a type of "dense-mode" join, allowing stub sites not
participating in Protocol Independent Multicast (PIM) to indicate membership
in IP multicast groups.
On Sat, 11 Jun 2005 ccie2be wrote :
>Hey Lee,
>
>See comments in-line.
>
>-----Original Message-----
> From:
nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Lee
>Carter
>Sent: Saturday, June 11, 2005 11:07 AM
>To: CCIE LAB
>Subject: Stub Multicast
Routing
>
>All,
>
>In looking at univercd documentation to configure stub
>multicast routing use:
>
>router a... Stub Host or end node
>
>routera(config)# ip multicast-routing
>routera(config)# interface ethernet0
>routera(config)# description Connection to hosts
>routera(config-if)# ip
address 10.0.1.1 255.255.255.0
>routera(config-if)# ip pim dense-mode
>routera(conifg-if)# ip igmp helper-address 10.0.0.2
>routera(config)#
interface ethernet1
>routera(config)# ip addres 10.0.1.1 255.255.255.0
>routera(config)# ip pim dense-mode
>routera(config)# description to Multicast
Rotuer
>
>router b... Real Multicast router
>
>routerb(config)# ip
multicast-routing
>routerb(config)# access-list 1 deny 10.0.0.1
>routerb(config)# interface ethernet 1
>routerb(config-if)# ip address
10.0.0.2 255.255.255.0
>routerb(config-if)# ip pim dense-mode
>routerb(config-if)# ip pim neighbor-filter 1
>routerb(config-if)# description
To Stub router
>
>My question is on Routerb's configuration...
>
>If I use ACL
1 which is deny host 10.0.0.1 but don't
>permit anyting else (per the
documentation on
>univercd) what will be allowed throubh the neighbor
>filter?
If nothing.. they why not make the ACL deny
>any?
>
>***********************************
>Lee, I believe you're not fully
understanding the functionality of the ip
>pim-filter command. My take on
what the Doc-CD says about this command is
>that by using this command, you
filter only pim traffic from the address
>specified in the acl - not any other
traffic. IOW, igmp traffic goes through
>just fine.
>
> From Doc-CD, "To
prevent a router from participating in Protocol Independent
>Multicast (PIM)
(for example, to configure stub multicast routing), use the
>ip pim
neighbor-filter command in interface configuration mode."
>
>******************************
>
>Also,
>
>Does igmp helper-addresses work
similar to ip helper
>addresses in that the interface that is configured
>with
the helper command will appear as the source when
>fowarding the broadcast
(multicast in this example)?
>
>If so, then it appears that the point is to
say stub
>multicast routing is really not making a peer with
>your directly
connected router and insted to some
>router(s) on links not directly attached
which I would
>then think the neighbor-filter would need a permit any
>after
the deny host 10.0.0.1...
>
>Thoughts?
>
>***********************
>Lee, from
the Doc-cd, " To cause the system to forward all Internet Group
>Management
Protocol (IGMP) host reports and leave messages received on the
>interface to
the specified IP address, use the ip igmp helper-address
>command in interface
configuration mode."
>
>It also says, "This command and the ip pim
neighbor-filter command together
>enable stub multicast routing. The IGMP host
reports and leave messages are
>forwarded to the IP address specified. The
reports are re-sent out the next
>hop interface toward the IP address, with
the source address of that
>interface. This command enables a type of
"dense-mode" join, allowing stub
>sites not participating in Protocol
Independent Multicast (PIM) to indicate
>membership in IP multicast groups."
>
>The way I understand this Stub Mcast feature is like this. Usually, igmp
>traffic only travels from hosts to the pim router on the same segment. IOW,
>igmp traffic doesn't leave the local segment. And, usually, from the
>last-hop-router to the next hop router towards the source, pim traffic is
>what goes back and forth. But, by configuring stub mcast, you're manually
>causing igmp traffic to travel one more hop and causing pim traffic to
>travel one less hop.
>
>Now, I suspect there's some brilliant reason to do
this besides providing
>ccie candidates with something else to think about on
the lab, but I'm not
>able to intuitively figure that out.
>
>HTH, Tim
>*****************************
>
>Link for their configuration (near bottom).
>http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fipr
>_c/ipcpt3/1cfmulti.htm#wp1003543
>
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