From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Sun Nov 26 2006 - 12:46:33 ART
Multicast uses a split-horizon like behavior to prevent traffic
loops. The incoming interface for a multicast feed cannot appear in the
outgoing interface list (OIL) for that same group. With partially
meshed NBMA networks this can be a problem because you may want to take
a feed in from on VC A on interface X and send it back out another VC B
on interface X. Running PIM in NBMA mode fixes this by treating VC A
and VC B as two separate interfaces in the OIL by associating the remote
endpoint's IP address with the outgoing interface. Look at the
difference in the "show ip mroute" output for groups that come in and go
out the NBMA interface when "ip pim nbma-mode" is on and off.
HTH,
Brian McGahan, CCIE #8593 (R&S/SP)
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
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> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> Salman Abbas
> Sent: Sunday, November 26, 2006 7:04 AM
> To: srdja blagojevic
> Cc: Mohamed Saeed; ccielab@groupstudy.com
> Subject: Re: IEWB - Ver 3 - Lab 8 - Task 5.4 ( ip pim nbma-mode)
>
> Hi guys,
>
> Let me tell you my observation. I found out that after using the
command
> "ip
> igmp join group 224.4.4.4" on vlan 4 interface on R4, i could ping
> 224.4.4.4from R1 but not from R5. Then I configured the command "ip
> pim nbma-mode" on
> R1 and magically I was able to ping the group from R5. Now this is in
> sharp
> contrast with the documentation of the ip pim nbma-mode command on the
> Cisco
> website. First of all, its not recommended for sparse-dense mode but
> rather
> for sparse-mode only. Secondly, its not a command that is meant to be
put
> on
> the hub router's interface everytime we want to ping from one spoke, a
> group
> that is on another spoke. What do you guys say????
>
> Regards,
>
> Salman
>
>
>
> On 11/26/06, srdja blagojevic <srdja1@pexim.co.yu> wrote:
> >
> > Mohamed,
> >
> > There are 2 things that I can remember on the top of my head right
now:
> >
> > - RPF check failure; there are redundant paths between R4 and R5:
vlan
> 45
> > and FR cloud. Check out your routing between R4 and R5. You can test
> this
> > by
> > shutting down vlan 45 on both routers.
> >
> > - task requirement asks that ping should be generated from vlan 52,
so
> you
> > should use extended ping on R5 with source interface in vlan 52 for
task
> > requirement testing.
> >
> >
> > hth,
> > Srdja
> >
> > -----Original Message-----
> > From: Mohamed Saeed [mailto:mohamed_saeed2@rayacorp.com]
> > Sent: Sunday, November 26, 2006 11:32
> > To: srdja blagojevic; ccielab@groupstudy.com
> > Subject: RE: IEWB - Ver 3 - Lab 8 - Task 5.4 ( ip pim nbma-mode)
> >
> > Hi Srdja,
> >
> > Thanks for your clarification regarding the sparse-dense mode issue.
> >
> > Although I have configured the "ip pim nbma-mode" I could not ping
> > 224.4.4.4 from R5. However, I could ping it from R1. Below are the
> mroute
> > of
> > both R1 and R5, Appreciate if you could shed some light to any thing
I
> may
> > miss:
> >
> > R1#sh ip mroute
> > 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
> > Timers: Uptime/Expires
> > Interface state: Interface, Next-Hop or VCD, State/Mode
> >
> > (*, 224.4.4.4), 00:00:08/stopped, RP 0.0.0.0, flags: D
> > Incoming interface: Null, RPF nbr 0.0.0.0
> > Outgoing interface list:
> > Serial0/1, Forward/Sparse-Dense, 00:00:08/00:00:00
> > Serial0/0, Forward/Sparse-Dense, 00:00:08/00:00:00
> >
> > (174.1.145.5, 224.4.4.4), 00:00:08/00:02:57, flags: PT
> > Incoming interface: Serial0/0, RPF nbr 0.0.0.0
> > Outgoing interface list:
> > Serial0/1, Prune/Sparse-Dense, 00:00:08/00:02:51
> >
> > (*, 224.0.1.39), 01:20:43/stopped, RP 0.0.0.0, flags: D
> > Incoming interface: Null, RPF nbr 0.0.0.0
> > Outgoing interface list:
> > Serial0/0, Forward/Sparse-Dense, 01:20:21/00:00:00
> > Serial0/1, Forward/Sparse-Dense, 01:20:43/00:00:00
> >
> > (150.1.1.1, 224.0.1.39), 01:20:43/00:02:13, flags: T
> > Incoming interface: Loopback0, RPF nbr 0.0.0.0
> > Outgoing interface list:
> > Serial0/0, Prune/Sparse-Dense, 00:06:41/00:02:13
> > Serial0/1, Forward/Sparse-Dense, 01:20:43/00:00:00
> >
> > (*, 224.0.1.40), 01:20:47/stopped, RP 0.0.0.0, flags: DCL
> > Incoming interface: Null, RPF nbr 0.0.0.0
> > Outgoing interface list:
> > Serial0/0, Forward/Sparse-Dense, 01:20:21/00:00:00
> > Serial0/1, Forward/Sparse-Dense, 01:20:46/00:00:00
> > Loopback0, Forward/Sparse-Dense, 01:20:47/00:00:00
> >
> > (150.1.3.3, 224.0.1.40), 01:19:45/00:02:47, flags: LT
> > Incoming interface: Serial0/1, RPF nbr 174.1.13.3
> > Outgoing interface list:
> > Loopback0, Forward/Sparse-Dense, 01:19:45/00:00:00
> > Serial0/0, Forward/Sparse-Dense, 01:19:45/00:00:00
> >
> > R1# ping 224.4.4.4
> >
> > Type escape sequence to abort.
> > Sending 1, 100-byte ICMP Echos to 224.4.4.4, timeout is 2 seconds:
> >
> > Reply to request 0 from 174.1.145.4, 76 ms Reply to request 0 from
> > 174.1.145.4, 132 ms
> >
> >
> >
> > R5#sh ip mroute
> > 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, z - MDT-data group sender,
> > 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
> >
> > (*, 224.4.4.4), 00:00:16/stopped, RP 0.0.0.0, flags: D
> > Incoming interface: Null, RPF nbr 0.0.0.0
> > Outgoing interface list:
> > Serial0/2/0, Forward/Sparse-Dense, 00:00:16/00:00:00
> >
> > (150.1.1.1, 224.4.4.4), 00:00:16/00:02:43, flags: PT
> > Incoming interface: Serial0/2/0, RPF nbr 174.1.145.1
> > Outgoing interface list: Null
> >
> > (174.1.145.1, 224.4.4.4), 00:00:16/00:02:43, flags: PT
> > Incoming interface: Serial0/2/0, RPF nbr 0.0.0.0
> > Outgoing interface list: Null
> >
> > (*, 224.0.1.39), 01:20:07/stopped, RP 0.0.0.0, flags: D
> > Incoming interface: Null, RPF nbr 0.0.0.0
> > Outgoing interface list:
> > Serial0/2/0, Forward/Sparse-Dense, 01:20:07/00:00:00
> >
> > (150.1.1.1, 224.0.1.39), 00:01:07/00:01:52, flags: PT
> > Incoming interface: Serial0/2/0, RPF nbr 174.1.145.1
> > Outgoing interface list: Null
> >
> > (*, 224.0.1.40), 01:22:03/stopped, RP 0.0.0.0, flags: DCL
> > Incoming interface: Null, RPF nbr 0.0.0.0
> > Outgoing interface list:
> > Serial0/2/0, Forward/Sparse-Dense, 01:22:03/00:00:00
> >
> > (150.1.3.3, 224.0.1.40), 01:20:07/00:02:21, flags: PLTX
> > Incoming interface: Serial0/2/0, RPF nbr 174.1.145.1
> > Outgoing interface list: Null
> >
> > Kind Regards
> > Mohamed ...
> >
> > -----Original Message-----
> > From: srdja blagojevic [mailto:srdja1@pexim.co.yu]
> > Sent: Sunday, November 26, 2006 11:52 AM
> > To: Mohamed Saeed; ccielab@groupstudy.com
> > Subject: RE: IEWB - Ver 3 - Lab 8 - Task 5.4 ( ip pim nbma-mode)
> >
> >
> > Mohamed,
> >
> >
> > in the task 5.2 you set AutoRP for all groups => your groups will
run in
> > sparse mode (ip pim sparse-dense mode mean: "if I have RP I will use
> > sparse,
> > else I will use dense mode")
> >
> > Since your groups are running in sparse mode you will need ip pim
> > nbma-mode
> > in hub-and-spoke topology.
> >
> > I also think that you need command ip igmp join-group 224.4.4.4 on
R4 to
> > meet task requirement.
> >
> > HTH,
> > Srdja
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> > Mohamed Saeed
> > Sent: Sunday, November 26, 2006 10:36
> > To: ccielab@groupstudy.com
> > Subject: IEWB - Ver 3 - Lab 8 - Task 5.4 ( ip pim nbma-mode)
> >
> > Hi All,
> >
> >
> >
> > In that task, we have R1, R4 and R5 in hub and spoke setup with R1
as
> > the
> > hub. PIM sparse-dense mode is running over the cloud. It is required
> > that
> > the Ethernet interface of R4 to receive multicast feed from R5
Ethernet
> > and
> > also to make R4 responds to ICMP ping to 224.4.4.4 group.
> >
> >
> >
> > First, I though there will be an issue with RPF and also I though I
> > should
> > use the "ip igmp" command to R4 to allow it responding to ICMP ping.
> > What I
> > found in the solution guide is that the only configuration done is
> > enabling
> > the "ip pim nbma-mode" command under the hub physical interface.
> >
> >
> >
> > As I know, that command is used to send multicast feed ONLY to the
DLCIs
> > that have multicast receivers in sparse mode. I wonder what that
command
> > is
> > supposed do in this setup. Also do not we need to enforce R4
Ethernet
> > interface to join the 224.4.4.4 group? Hope if someone could help
with
> > that.
> >
> >
> >
> > Kind Regards
> >
> >
This archive was generated by hypermail 2.1.4 : Fri Dec 01 2006 - 08:05:48 ART