From: kym blair (kymblair@hotmail.com)
Date: Fri Mar 14 2003 - 21:37:50 GMT-3
Elmer,
When starting to learn multicast, begin with dense-mode; it's the easiest:
e0
ROUTER1
s0
ip pim dense-mode
|
|
s0
ip pim dense-mode
ROUTER2
s1
ip pim dense-mode
|
|
s1
ip pim dense-mode
ROUTER3
s0
ip pim dense-mode
|
|
s0
ip pim dense-mode
ROUTER4
e0
ip pim dense-mode
ip igmp join-group 227.7.7.7
Now, from Router1 "ping 227.7.7.7" and see who answers. (See if there is
any difference if you source this ping from E0 who is not participating in
multicast, and from s0 who is participating.) Add "ip igmp join-group
227.7.7.7" a few more places and see who answers.
Next, add a Catalyst switch after ROUTER4 and attach ROUTER5 and ROUTER6 on
the same vlan, and play with join-group on them. You don't need to do any
special configuration with the switch. NOTE: If you would like to be able
to prune the switch ports quickly when ROUTER5 or ROUTER6 leave, you could
add CGMP to ROUTER4 E0 and to the Catalyst switch so the router can notify
the switch to prune. In the real world, you would definitely want to run
CGMP.
Once you are comfortable with Dense-mode, try sparse-mode (replace the pim
dense-mode statements on all the interfaces). Sparse-mode is for when you
want to MANUALLY set up a Rendezvous Point for multicast speakers to send
their stream for multicasting out rather than flooding; in sparse-mode. You
can select any router as the RP; typically, it is close to the first
multicast speaker. To manually designate a Rendezvous-Point, just add "ip
pim rp-address 192.168.5.5" to all the other routers (192.168.5.5 can be any
interface on the RP router; loopback is recommended); the RP will learn from
the others that it is the RP; if you want, you can add the statement to the
RP, but it isn't necessary. Later, if other speakers want to source
multicast, they can use the same RP (preferred), or ask the administrator to
establish another RP for them.
After static RP, try auto-RP. Auto RP requires sparse-dense-mode ... dense
mode for the RP to announce what groups it's hosting, and sparse mode for
multicasting traffic. Remove all the "ip pim rp-address 192.168.5.5" from
all the routers and add the following to the router you select to be the RP:
ip pim send-rp-announce loop0 scope 10 group-list 7
access-list 7 permit 227.7.7.7 255.255.255.255
ip pim send-rp-discovery loop0 scope 10
NOTE: the "announce" statement is from the RP. The "discovery" statement is
from the Mapping Agent. At first, make these the same router for
simplicity. Later, try moving the Mapping Agent to another router. In a
large network, you would have several Mapping Agents to tell the world where
the RP is. If you are running multicast over Frame Relay, you will need to
experiment with where you place the MA.
The competition for Auto-RP is "Bootstrap RP". You would replace the RP's
"announce" statement with "ip pim rp-candidate loop0" and you would replace
the MA's "discovery" statement with "ip pim bsr-candidate loop0 group-list
7". I believe BSR is purely sparse-mode, so you could change from
sparse-dense-mode on all the interfaces; I'm not sure though, so you should
research CCO.
Those are the three major flavors of PIM multicast. Later, you will want to
study the smaller issues. For example, if you have a Frame Relay multipoint
hub with multiple spokes who are also participating in multicast, you don't
want one spoke to send a "leave" message to the hub and have the other
spokes choked off; so you would add "ip pim nbma-mode" to the hub so it
learns each multicast spoke by individual IP address and won't prune the
whole interface if one spoke "leaves".
You will also want to study "ip pim accept-register <acl>", "ip pim
accept-rp x.x.x.x <acl>", "ip multicast use-functional", "ip multicast
helper-map", and on the switch that doesn't do cgmp "ip igmp snooping VLAN31
static 01005E070707 int Fast0/2".
I doubt you need to know DVMRP or MOSPF since Cisco's PIM is so good, but it
wouldn't hurt to read up on these a little.
Hope this is useful. Kym
>From: "cebuano" <cebu2ccie@cox.net>
>Reply-To: "cebuano" <cebu2ccie@cox.net>
>To: <ccielab@groupstudy.com>
>Subject: Need a sample and SIMPLE multicast scenario
>Date: Fri, 14 Mar 2003 00:12:18 -0500
>
>Hello gang.
>Does anyone have a simple multicast (PIM-SM or DM) scenario that they
>would like to share? Please contact me directly.
>I just need something to get me started on the fundamentals and build on
>more complex additions as I go along on this topic. Unfortunately with
>my current setup I don't have the ability to install a Multicast server.
>I'm using my old laptop as my console access for now.
>Thanks.
>
>Elmer
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