RE: Multicast - NBMA

From: Braychuck Vitaliy (Vitaliy.Braychuck@incom.ua)
Date: Wed Jan 21 2009 - 13:13:20 ARST


Consider your first question, somewhere (probably in Cisco documentation) I have read that you should use MA on hub or behind hub router only, not on spokes. This happening because multicast groups 224.0.1.39 and 224.0.1.40 are normally floods in dense mode, so R3 don't get these packets. So your spoke router (MA) should have virtual circuits to all router in frame-relay networks as it wants to be MA for multicast network.

Q2: If your hub router will be MA, you don't need tunneling.

Q3: In dense mode to forward multicast packets from one spoke to the second spoke it is needed in tunnel or VC between them.

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Nitro Drops
Sent: Wednesday, January 21, 2009 2:04 PM
To: ccielab@groupstudy.com
Subject: Multicast - NBMA

Hi All,

Have been practising multicast by placing around RP and MA around in a
Hub-N-Spoke.

R3 - Spoke1 > RP
R2 - Hub
R4 - Spoke2 > MA

R3 s2/1 >> s2/1 R2 s2/1 >> s2/1 R4

Full Reachability using EIGRP.

R2
interface Serial2/1
 ip address 155.8.10.2 255.255.255.0
 ip pim nbma-mode <<< included this
 ip pim sparse-mode
 encapsulation frame-relay
 no ip split-horizon eigrp 1
 no ip mroute-cache
 frame-relay map ip 155.8.10.3 203 broadcast
 frame-relay map ip 155.8.10.4 204 broadcast
 no frame-relay inverse-arp
!
ip pim autorp listener

R3 (RP)
ip pim autorp listener
ip pim send-rp-announce Loopback0 scope 16

R4 (MA)
ip pim autorp listener
ip pim send-rp-discovery Loopback0 scope 16

QNS 1 : I kept encountering the announcement 224.0.1.39 from RP > MA got stuck
at the Hub, even though i have configured "ip pim nbma mode". Did i miss out
anything?

P(0): s=150.8.3.3 (Serial2/1) d=224.0.1.39 id=299, ttl=15, prot=17,
len=52(48), mroute olist null
IP(0): s=150.8.3.3 (Serial2/1) d=224.0.1.39 id=322, ttl=15, prot=17,
len=52(48), mroute olist null

    l
R2#sh ip mro
IP Multicast Routing Table

Outgoing interface flags: H - Hardware switched, A - Assert winner
 Timers: Uptime/Expires
 Interface state: Interface, Next-Hop or VCD, State/Mode

(*, 224.0.1.39), 00:14:52/stopped, RP 0.0.0.0, flags: DC
  Incoming interface: Null, RPF nbr 0.0.0.0
  Outgoing interface list:
    Serial2/1, Forward/Sparse, 00:14:06/00:00:00

(150.8.3.3, 224.0.1.39), 00:00:46/00:02:13, flags: PT
  Incoming interface: Serial2/1, RPF nbr 155.8.10.3
  Outgoing interface list: Null

(*, 224.0.1.40), 00:15:04/00:02:18, RP 0.0.0.0, flags: DCL
  Incoming interface: Null, RPF nbr 0.0.0.0
  Outgoing interface list:
    Serial2/1, Forward/Sparse, 00:14:07/00:00:00

QNS 2 : if all the 3 routers are running 'sparse-dense' mode, a tunnel will be
required between the spokes. Since 'ip nbma mode' is only supported on
'sparse-mode'

QNS 3 : if all the 3 routers are running 'dense' mode, R3 (Server) R2
(Client), again a tunnel will be required between the spokes, since the
incoming CANT be the same as the outgoing interface on the multicast routing
table.

Cheers
Nit



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