From: Huan Pham (huan.pham@valuenet.com.au)
Date: Thu Jan 17 2008 - 03:04:54 ARST
Hi Brian,
Thanks, I need to turn off fast switching in order to see all multicast
traffic. I can see all traffic now.
> If you haven't enabled multicast routing why would you expect the router
> to process multicast traffic?
By "process" I think you meant "multicast-forwarding". Because normally, I
would understand it differently, including receiving, sending.
On the last router R4 (which pretends to be a PC running multicast
application, and it is just receiving multicast traffic), I do not need to
turn on multicast routing. However, I can see all multicast traffic sent to
it using "debug ip packet" (NOT debug ip mpacket). A multicast packet is
also an IP packet, so I should be able to see it using "debug ip packet".
However, I can not see multicast packets using "debug ip mpacket" because
multicast routing is not turned on that router.
On the transit multicast router, when I turn on only "debug ip packet" I can
only see multicast packets that this router SENDS, or RECEIVES, but not
forwarding (i.e. multicast routing).
BTW, it would be good if you can update the PIM Dense Mode lab in your
Workbook Volume1 in the next release. The current lab does not have "no ip
mroute-cache" command under the interface, and when you enable "debug ip
mpacket", you need to mention to turn off fast-switching.
I am much clearer now, thanks again :-)
R4#show ip multicast
Multicast Routing: disabled
Multicast Multipath: disabled
Multicast Route limit: No limit
Multicast Triggered RPF check: enabled
Multicast Fallback group mode: Sparse
R4#debug ip packet
IP packet debugging is on
*Nov 7 20:43:56.331: IP: s=24.0.0.4 (local), d=224.0.0.5 (FastEthernet0/0),
len 80, sending broad/multicast
*Nov 7 20:43:57.619: IP: s=13.0.0.1 (FastEthernet0/0), d=224.1.1.1, len 44,
rcvd 2
*Nov 7 20:43:59.779: IP: s=24.0.0.2 (FastEthernet0/0), d=224.0.0.5, len 80,
rcvd 0
*Nov 7 20:44:02.619: IP: s=13.0.0.1 (FastEthernet0/0), d=224.1.1.1, len 44,
rcvd 2
*Nov 7 20:44:02.891: IP: s=24.0.0.2 (FastEthernet0/0), d=224.0.0.1, len 28,
rcvd 0
-----Original Message-----
From: Brian Dennis [mailto:bdennis@internetworkexpert.com]
Sent: Thursday, 17 January 2008 1:23 PM
To: Huan Pham; ccielab@groupstudy.com
Subject: Re: MULTICAST - debug ip mpacket
> - 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 you haven't enabled multicast routing why would you expect the router
to process multicast traffic?
> - If a router runs multicast and does not join any group (a transit
> multicast router), the debug ip packets DOES NOT show anything either.
You need to disable fast switching for multicast traffic under the
interfaces. You can do this by using the "no ip mroute-cache" command.
> - 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".
Do you mean "debug ip mpacket"?
Brian Dennis, CCIE4 #2210 (R&S/ISP-Dial/Security/SP)
bdennis@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987
Direct: +1-775-544-1653 (Outside the US and Canada)
>----- Original Message -----
Subject: MULTICAST - debug ip mpacket
Date: Tue, January 15, 2008 15:31
From: "Huan Pham" <huan.pham@valuenet.com.au>
> 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
>
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