GroupStudy.com GroupStudy.com - A virtual community of network engineers
 Home  BookStore  StudyNotes  Links  Archives  StudyRooms  HelpWanted  Discounts  Login
MULTICAST - debug ip mpacket posted 01/15/2008
[Chronological Index] [Thread Index] [Top] [Date Prev][Date Next] [Thread Prev][Thread Next]


Hi GS,

I have difficulty understanding the "debug ip mpacket" command. My
understanding is that it should show all the multicast packets that a router
receives, sends or forwards. It seems that this is not the case!  I can only
see the multicast packets when the router run multicast routing AND join a
multicast group. 

- If a router runs unicast and join a multicst group (pretending as a PC
listening to multicast traffic), the debug ip packets DOES NOT show any
multicast packets.

- If a router runs multicast and does not join any group (a transit
multicast router), the debug ip packets DOES NOT show anything either.

- In the transit Multicast router (R2), I can not see the multicast packet
using "debug ip packet". In the destination host (R4, running only Unicast)
I can see multicast packets using "debug ip packet".


I would like to know if this is a normal behavior or I miss something.


My config is below. I run PIM Dense mode. The multicast forwarding works
fine. 


Thanks,





TOPOLOGY

R1 (src) --------- R3 ----------------R2 -------------R4 (dest)
     	13.0.0.0/8		23.0.0.0/8		24.0.0.0/8





R1#
!

! This is to generate Multicast traffic
ip sla monitor 1
 type udpEcho dest-ipaddr 224.1.1.1 dest-port 12345 source-ipaddr 13.0.0.1
control disable
 timeout 0
 frequency 5
ip sla monitor schedule 1 life forever start-time now
!
!
interface FastEthernet0/0
 ip address 13.0.0.1 255.0.0.0
!
router ospf 1
 network 0.0.0.0 255.255.255.255 area 0




R3#
!
no ip domain lookup
ip multicast-routing 
!
!         
!
interface FastEthernet0/0
 ip address 13.0.0.3 255.0.0.0
 ip pim dense-mode
!
interface Serial1/3
 ip address 23.0.0.3 255.0.0.0
 ip pim dense-mode
!
router ospf 1
 network 0.0.0.0 255.255.255.255 area 0




R2#

ip multicast-routing 
!
interface FastEthernet0/0
 ip address 24.0.0.2 255.0.0.0
 ip pim dense-mode
!
interface Serial1/1
 ip address 23.0.0.2 255.0.0.0
 ip pim dense-mode
!
router ospf 1
 log-adjacency-changes
 network 0.0.0.0 255.255.255.255 area 0
!




R4#
!
interface Ethernet0/0
 ip address 24.0.0.4 255.0.0.0
 ip igmp join-group 224.1.1.1
!
!
router ospf 1
 network 0.0.0.0 255.255.255.255 area 0



R3#sh ip mroute 224.1.1.1
IP Multicast Routing Table
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,
       L - Local, P - Pruned, R - RP-bit set, F - Register flag,
       T - SPT-bit set, J - Join SPT, M - MSDP created entry,
       X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
       U - URD, I - Received Source Specific Host Report, Z - Multicast
Tunnel
       Y - Joined MDT-data group, y - Sending to MDT-data group
Outgoing interface flags: H - Hardware switched, A - Assert winner
 Timers: Uptime/Expires
 Interface state: Interface, Next-Hop or VCD, State/Mode

(*, 224.1.1.1), 00:35:28/stopped, RP 0.0.0.0, flags: DCL
  Incoming interface: Null, RPF nbr 0.0.0.0
  Outgoing interface list:
    Serial0/3, Forward/Dense, 00:32:37/00:00:00
    FastEthernet0/0, Forward/Dense, 00:34:02/00:00:00

(13.0.0.1, 224.1.1.1), 00:35:25/00:02:59, flags: LT
  Incoming interface: FastEthernet0/0, RPF nbr 0.0.0.0
  Outgoing interface list:
    Serial0/3, Forward/Dense, 00:32:37/00:00:00



R2#sh ip mroute 224.1.1.1
IP Multicast Routing Table
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,
       L - Local, P - Pruned, R - RP-bit set, F - Register flag,
       T - SPT-bit set, J - Join SPT, M - MSDP created entry,
       X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
       U - URD, I - Received Source Specific Host Report, Z - Multicast
Tunnel
       Y - Joined MDT-data group, y - Sending to MDT-data group
Outgoing interface flags: H - Hardware switched, A - Assert winner
 Timers: Uptime/Expires
 Interface state: Interface, Next-Hop or VCD, State/Mode

(*, 224.1.1.1), 00:29:46/stopped, RP 0.0.0.0, flags: DC
  Incoming interface: Null, RPF nbr 0.0.0.0
  Outgoing interface list:
    FastEthernet0/0, Forward/Dense, 00:27:21/00:00:00
    Serial0/1, Forward/Dense, 00:29:46/00:00:00

(13.0.0.1, 224.1.1.1), 00:29:45/00:02:56, flags: T
  Incoming interface: Serial0/1, RPF nbr 23.0.0.3
  Outgoing interface list:
    FastEthernet0/0, Forward/Dense, 00:27:21/00:00:00

R2#debug ip mpacket
IP multicast packets debugging is on
R2#

! NOTHING SHOWS UP


R2#
R2#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
R2(config)#int s0/1
R2(config-if)#ip igmp join 224.1.1.1
R2(config-if)#
R2#
Jan 16 12:01:48.771: %SYS-5-CONFIG_I: Configured from console by console
Jan 16 12:01:51.215: IP(0): s=13.0.0.1 (Serial0/1) d=224.1.1.1
(FastEthernet0/0) id=0, ttl=253, prot=17, len=44(44), mforward
Jan 16 12:01:56.215: IP(0): s=13.0.0.1 (Serial0/1) d=224.1.1.1
(FastEthernet0/0) id=0, ttl=253, prot=17, len=44(44), mforward
Jan 16 12:02:01.215: IP(0): s=13.0.0.1 (Serial0/1) d=224.1.1.1
(FastEthernet0/0) id=0, ttl=253, prot=17, len=44(44), mforward
Jan 16 12:02:06.215: IP(0): s=13.0.0.1 (Serial0/1) d=224.1.1.1
(FastEthernet0/0) id=0, ttl=253, prot=17, len=44(44), mforward
Jan 16 12:02:11.211: IP(0): s=13.0.0.1 (Serial0/1) d=224.1.1.1
(FastEthernet0/0) id=0, ttl=253, prot=17, len=44(44), mforward
Jan 16 12:02:16.211: IP(0): s=13.0.0.1 (Serial0/1) d=224.1.1.1
(FastEthernet0/0) id=0, ttl=253, prot=17, len=44(44), mforward
Jan 16 12:02:21.211: IP(0): s=13.0.0.1 (Serial0/1) d=224.1.1.1
(FastEthernet0/0) id=0, ttl=253, prot=17, len=44(44), mforward