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multicast over frame-relay issue !!

Marwan ALshawi
VIP Alumni
VIP Alumni

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 !!!

26 Replies 26

Giuseppe Larosa
Hall of Fame
Hall of Fame

Hello Marwan,

give a look at the following chapter from 12.4 multicast config guide

ip pim nbma-mode command can help

http://www.cisco.com/en/US/docs/ios/ipmulti/configuration/guide/imc_over_atm_p2mp_ps6350_TSD_Products_Configuration_Guide_Chapter.html

Hope to help

Giuseppe

Edison Ortiz
Hall of Fame
Hall of Fame

Please post the output from:

show ip mroute

show ip pim rp mapping

show ip pim interface

show ip pim neigh

show ip os neigh

from the 3 routers.

__

Edison.

hi Edison

i dont have this output now

but i can give what you looking for frothis show comands

for mroute

spoke show the outgoing interfac as the FR interface

but the issue with the hub

although it has ip pim nbma-mode

as i mention firt time with show ip mroute

the hub shows

for the sopke i ping FROM the ip address in S and the destination ijmp grup in the G

and the incoming and outgoing interfaces correct

howver fter first success ping

on the hub the outgoing interface for this spok ( the one i ping from ) the outgoing interface shown as NULL

here why i am confsed

even if i put he command ip pim spt-thrshould infinity no lck !!!

for mappping they all see the hub as the RP

becuase i did in the spoke autorp listner !!!

if you need anymore details let me know ?

but why the first packet go then the outgoing interface in the hub change to NULL ??

thanks again

I can't duplicate your problem here and it could be an underlying problem with the IGP.

Here is my lab, R1 (Hub) R2 and R3 (Spokes)

R1:

interface Serial1/0

ip address 192.168.123.1 255.255.255.0

ip pim nbma-mode

ip pim sparse-mode

encapsulation frame-relay

no ip mroute-cache

serial restart-delay 0

frame-relay map ip 192.168.123.2 102 broadcast

frame-relay map ip 192.168.123.3 301 broadcast

no clns route-cache

R2:

interface Serial1/0

ip address 192.168.123.2 255.255.255.0

ip pim sparse-mode

encapsulation frame-relay

ip ospf priority 0

serial restart-delay 0

frame-relay map ip 192.168.123.3 201

frame-relay map ip 192.168.123.1 201 broadcast

no clns route-cache

R3:

interface Serial1/0

ip address 192.168.123.3 255.255.255.0

ip pim dr-priority 0

ip pim sparse-mode

encapsulation frame-relay

ip ospf priority 0

no ip mroute-cache

serial restart-delay 0

frame-relay map ip 192.168.123.2 103

frame-relay map ip 192.168.123.1 103 broadcast

no clns route-cache

end

__________

I made sure R1 was the DR for that segment by changing the OSPF priority on the spokes.

I configured R1 with Auto-RP by using loopback and here are the mappings all routers:

PIM Group-to-RP Mappings

Group(s) 224.0.0.0/4

RP 150.1.1.1 (?), v2v1

Info source: 150.1.1.1 (?), elected via Auto-RP

Uptime: 00:39:54, expires: 00:02:49

_____

Now, I'm going to do a join on R3 and do a ping from R2..

R3(config)#int lo0

R3(config-if)#ip igmp join-group 229.3.3.3

R3(config-if)#do show ip mroute 229.3.3.3

(*, 229.3.3.3), 00:00:07/00:02:52, RP 150.1.1.1, flags: SJCL

Incoming interface: Serial1/0, RPF nbr 192.168.123.1

Outgoing interface list:

Loopback0, Forward/Sparse, 00:00:07/00:02:52

_____

Verify the join was sent to the RP:

R1#sh ip mroute 229.3.3.3

(*, 229.3.3.3), 00:01:42/00:02:47, 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, 00:01:42/00:02:47

______

Ping from the other spoke:

R2#ping 229.3.3.3 repeat 10

Type escape sequence to abort.

Sending 10, 100-byte ICMP Echos to 229.3.3.3, timeout is 2 seconds:

Reply to request 0 from 192.168.123.3, 152 ms

Reply to request 1 from 192.168.123.3, 92 ms

Reply to request 2 from 192.168.123.3, 128 ms

Reply to request 3 from 192.168.123.3, 136 ms

Reply to request 4 from 192.168.123.3, 140 ms

Reply to request 5 from 192.168.123.3, 132 ms

Reply to request 6 from 192.168.123.3, 116 ms

Reply to request 7 from 192.168.123.3, 104 ms

Reply to request 8 from 192.168.123.3, 192 ms

Reply to request 9 from 192.168.123.3, 124 ms

_______

Check the hub mroute table now:

R1#sh ip mroute 229.3.3.3

(*, 229.3.3.3), 00:03:54/00:02:32, 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, 00:03:54/00:02:32

(192.168.123.2, 229.3.3.3), 00:01:04/00:02:54, flags: T

Incoming interface: Serial1/0, RPF nbr 0.0.0.0

Outgoing interface list:

Serial1/0, 192.168.123.3, Forward/Sparse, 00:01:04/00:01:55

HTH,

__

Edison.

Hi Edison

first Thank you for this config i will give it try tonight

however i did the same as u did mostly except i did not put

th following command on the hub inteerface

no ip mroute-cache

dose this make deffrence ??

also for rp in the hub i did it like

int lo0

ip pim spare-mode

ip pim send-rp-announce looback 0 secope 16

ip pim send-rp-discovery loopback 0 scope 16

in addition to that

IF I DONTPUT the AUTORP LISTNER on SPOKES they will not know about the RP

becuase u know there is know dense ???!!!

let me know if something missing

as i mentioned

why it wor when i have it as ospf poin-to-multipoint

but with non-broadcast and eigrp Not ??!!!

Thanks again

however i did the same as u did mostly except i did not put

th following command on the hub inteerface

no ip mroute-cache

dose this make deffrence ??

No, I did it for the debugs.

It works the same w/o it.

IF I DONTPUT the AUTORP LISTNER on SPOKES they will not know about the RP

becuase u know there is know dense ???!!!

Correct.

let me know if something missing

Try forcing the hub to be the PIM DR as well as the OSPF DR.

as i mentioned

why it wor when i have it as ospf poin-to-multipoint

but with non-broadcast and eigrp Not ??!!!

point-to-multipoint does not use the concept of the DR and that's the reason I told you, something is wrong with the underlying IGP.

I'll check with EIGRP later on and see if I can duplicate the problem.

__

Edison.

Try forcing the hub to be the PIM DR ?

how can this be done and what is the defrence from from RP role ?

by the way sometimes they mentioned about Mapping agent MA is that means the router with the discovery command ??

which we have it in my case on the same router !!??

also if i have question say this router need t be the group maping

sometimes i see it solved as above with discovery and filltering if required HOEVEVER somtimes i see it used as BSR ??

why and how i can kno which one to use

Thanks again mate

No problems with EIGRP, see attached file.

i will try it tonight :)

by the way why u did used

neighbor 192.168.123.3 Serial1/0

neighbor 192.168.123.2 Serial1/0

while we done need to send roting as unicast

it should work without it right ?

Hi Edison

i have attached the router config i have tried th ething u have mentioned but no luck

R1 hub

R2 and R3 spokes

R4 just a router connected to R3 and has defualt route to R3 and i joined it to an ijmgp group for ping test

first ping from R2 go and the subsequent NOT

other routers ping normally

also if u see in router 1 the outgoing interface for R2 to the gorup i use is Null

in router 4 for all other router shows null but they can ping except R2

any idea will be helpful cause i got confused all configred ok but not luck !!

thank you

Unable to duplicate.

Based on your attachment, the Hub is Pruning the S,G although you have a pim nbma on the interface so it seems to be a bug.

Try with a different IOS.

Posting configs with R4 attached to R3.

HTH,

__

Edison.

hi Edison

based on my config it should work i mean the config is ok ?

because i just get confused about it

about the comment bellow from mohamed

the RPF not the issue becuase it is just simple hub and spoke

even not full meshed network

and the traffic should go R1 !!!

Thanks Edison, by the way if you think my config OK becuase as i told you only with OSPF non-broadcast and eigrp dose not work !!

do you think becuase i use GNS3 for this ?!

Thanks again

I will let Mohamed discuss his logic on RPF since I don't see any RPF problem on the topology.

As you see from my configs, EIGRP & OSPF worked identically.

BTW, my lab was also done on GNS3, using 7200 routers and 12.2(25)S15 image.

HTH,

__

Edison.

Mohamed Sobair
Level 7
Level 7

Marwan,

what is 225.0.0.1 represets? If you are Pinging from IGMP group assigned on router-2 interface to the Source which should be 150.x.x.x should be successful and its only a source of check.

The RPF method state the following:

If the incoming Interface for the multicast packet doesnt lead back to the source which is (R1) in your case,then the RPF fails and multicast packet is dropped.

Make sure that R1 source of the multicast packet is reachable via the same Interface of the recieved incoming multicast packet. (You will need to source the Ping from that Interface) OR you have to configure the following:

IP mroute "Source addresss" "subnet Mask" exit interface.

HTH

Mohamed

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