02-16-2009 01:37 PM - edited 03-06-2019 04:04 AM
i have simple hub and spoke tpology
the hub configured with to map statments of frame-relay point to both spoks with broadcast word
spoks has one with broadcast word for the hub other one only map the other spok and point it to the local DLCI
simple and everyone ping each other
now i run ospf over this network
and we know by defualt it is non-broadcast then i add the neighbor command on the hub point to each spoke
now evrthing works fine as well
Multicast
the hub is the RP and discovery comand entered as well
one router behind the sopks joined an igmp group
each router run pim sapre-mode and the hub in addition to that has pim nbma-mode
the problem is
everything OK every on ping the joined igmp group
ecept from the other spoke
when i ping forst packet get replay and anything after first packet NO
in the hum and the RP as well what i noticed
first ping there is outgoing interface for that spoke for the subsequent the outgoing interface shows as NULL !!!!
however when i run ospf as poin-to-multipoint works fine
with EIGRP the same issue (split-horizon disabled)
any Idea Guys !!!
02-17-2009 02:06 PM
Edison,
The original poster has claimed that he can perform ping from all routers except R2? and I have suggested the following:
Since all routers recieved their mapping information and they have route back to the RP, then the possible cause is the Source of the ICMP packet from R2 is not the incoming interface for the multicast packet. I have also suggested him to configure Static IGMP Group on one of R2's Ethernet Interface and perform normal ping sourced from the serial Interface while making sure the outgoing interface for the ICMP packet is an RPF interface.
Another question is why Marwan is performing ping to 225.x.x.x Group from R2? what is this going to accomplish?
Mohamed
02-17-2009 02:22 PM
Hi Mohamed
i do this for CCIE LAB !
and if it is RPF problem then in this case i could not have been ble to get any response or reply when i ping
while i do have first packet with replay and the others failes which exclude RPF!
Edison i use the same as yours but not sure what IOS version exactly i will check tonight
by the way my config same as yours then can i consider my config right? and the logic i do my multicast over FR with NBMA is right as well ??
one more thing why u used neighbor command with eigrp without it it should work as well ??
thank you
02-17-2009 03:12 PM
Marwan,
I tried to match your config as close as possible and I'm unable to duplicate what you are seeing.
Per your config output, you get the join:
From R3
(*, 225.1.1.1), 00:13:38/stopped, RP 150.1.1.1, flags: S
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
Serial1/0, 10.1.1.3, Forward/Sparse, 00:13:12/00:02:35
Then the ip pim nbma-mode isn't doing what is supposed to do then the router prunes the S,G:
(10.1.1.2, 225.1.1.1), 00:00:05/00:02:55, flags: PT
Incoming interface: Serial1/0, RPF nbr 0.0.0.0
Outgoing interface list: Null
With my config, I get the join from R3:
(*, 225.1.1.1), 00:02:47/00:02:43, RP 150.1.1.1, flags: S
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
Serial1/0, 192.168.123.3, Forward/Sparse, 00:02:47/00:02:43
and the nbma mode kicks in by listing S0/1 with the unicast information from each router of the link:
(192.168.123.2, 225.1.1.1), 00:01:21/00:02:45, flags: T
Incoming interface: Serial1/0, RPF nbr 0.0.0.0
Outgoing interface list:
Serial1/0, 192.168.123.3, Forward/Sparse, 00:01:21/00:01:39
As you can see, the ping is coming from R2 to R3.
________
As for the EIGRP neighbor statement, it does not factor into problem. It works the same with or without.
__
Edison.
02-17-2009 03:28 PM
Ok upon this
i can guess it is more IOS issue as said rather than config
becuase my config since first time sae as yours.. and with Mcast as you know there is no much config it just concepts need to be applied correctly
i think i need to change the IOS otherwise it will not work for ever becuase no way to configure it other than this way right ..!!
thanks for you help
02-17-2009 04:24 PM
Marwan,
I have good news. I was able to duplicate your problem.
Try creating a loopback in R2.
I deleted the loopback in R2 and the hub pruned the S,G like in your lab.
Very interesting and I wonder if this is a GNS3 behavior. I don't have real routers to test right now but this is very strange.
__
Edison.
02-17-2009 04:43 PM
Further testing...
It seems the behavior (at least on GNS3), you need to have more than one Layer3 interface in up/up state if you have the router acting as a Mcast Server.
I did the opposite and setup R2 as the Mcast client with R3 being the server.
R3 is connected to R4 so it has two Layer3 links hence there is no need for loopback.
Multicast is working fine on this scenario.
__
Edison.
02-17-2009 07:10 PM
Hi Edison
really interesting and strange !!!!
i will try it
by the way do i expect it in the CCIE LAB as well :)
i think this is only in gns3 because i have never seen a document or bock mentioned about this point !!
i think the copy right for this will be yours :)
thanks again i will let you know after try it
by the way i have to make this loopbackaddress Mcast enabled ??
02-17-2009 09:10 PM
You won't expect that kind of behavior in the CCIE lab as most routers will have multiple L3 interfaces.
The fact that we created a router with just one interface and in your case without a loopback, created the issue.
Routers aren't that good for Mcast server/client function, their function is to be Mcast routers.
No, you don't need to enable PIM on the loopback.
HTH,
__
Edison.
02-18-2009 03:23 AM
actually i did what you have notced
but it was good to some extend
ping from R3 to R2 as R2 joind a group dose the ping ffrom 8 i get about 3 replyes whihc means ok but somthing wrong maybe with GNS3 !!!!
from R2 to R3 or R4 the same problem
anyway i think this is the only way to configure the Mcast over FR
thank you for your help
02-18-2009 12:49 PM
Hi Edison
i have somthing confused me
in multicast section
i see in internetworkexpert workbooks sometimes when the question say this router will be resposible for RP to group maping
they solved as RP agent with discovery comaand
and in others useing BSR
when i have to use BSR
thanks
02-18-2009 01:07 PM
Why people fail in the CCIE Lab is mostly due to interpreting what is asked.
It's very hard to tell you when to choose one technology over the other without reading the whole workbook.
Often the answer is tied to another underlying technology that is part of that Lab.
Other times, the answer is there with some hints like:
Use PIM version 2.0
or
Use PIM version 1.5
or
Use PIM described on RFC 5059
Understand?
I'm afraid, you need to practice and practice. There isn't a straight answer to this type of query.
__
Edison.
02-18-2009 02:19 PM
Hi Edison
i agree with you
because with multicasting and IPV6 there is no alot practice i think i need to cover all posible case as i can
for example the hints you have mentioned very nice
thats why i need to know what hints should i see to use this one or that one
for example maybe the type of network effect the choice with frame-relay and ospf
we need to see what frame-relay we hav P2P or P2multipoint and so on then we can decied
i am aware aboutthat thanks
but for example i will give now somthing i am thinking about confusing HSRP solusion
there is to labs in he IE workbook
both of them asked to track the connection to the FR cloud OK
buut one of them solved with normaway which is track interface serial x/x
the other one solved in a way i liked it
lets say the 2 spokes are HSRP peeers and they have to track the connection to the FR cloud i mean the active one as above
but what they did
the created a tunnel interface between the active HSRP(spoke) and the hub router and they put the tracked interface as the tunnel
it is interesting one i tried it and worked fine
but which one rom your experince will be considered the right one ( or both works)
the question ask the same and the case mostly the same
thanks again :)
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