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multicast WAN edge router sparse mode

Hi All

Hope you well. I have a multicast issue and was wondering if someone can help. We have multiple remote sites connected to hub end router and some sites cant receive multicast feed. we are using pim sparse mode with static RP. every time i try to ping multicast feed from lan switch i do get 

(*,G) entry with correct RP, RPF nbr and incoming interface on LHR but for OIL interface iam getting none. on Last hop router (LHR) i should see OIL interface as pointing to lan since igmp join request is coming from LAN.

Also i do see (lan src ip , G) entry in mrouting table but again incoming interface is pointing to lan, no rp details and outgoing interface is WAN.

can someone advise or point iin right direction. thanks

regards

M

1 Accepted Solution

Accepted Solutions

You will see that because the switch is acting as the source for a multicast stream so your WAN router is recording it correctly.

If you are trying to troubleshoot receiving multicast at the remote site then the above is not a valid test and tells you nothing.

What is the muilticast group address you are trying to join at the remote site ?

What does the mroute table show for that group address ?

Jon

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29 Replies 29

Jon Marshall
VIP Community Legend VIP Community Legend
VIP Community Legend

Can you clarify what you mean about the (<src IP>, G) entry ?

The src IP should be the sender which is presumably at the main site.

Also is the RP at the main site and is it actually the hub router ?

Jon

Hi Jon

Thanks for reply, i issue ping to multicast address and source it from lan switch .

lan switch= ping 239.101.101.10 source 192.168.1.1

and then when i do show ip mroute on wan edge  router for that site (LHR) i see one of the entry as being (192.168.1.1, 239.101.101.10) with LAN interface on router as being incoing interface and OIL is wan interface.

RP reside behind hub router in the core. Let me know if you need any other info, thanks alot.

regards

M

You will see that because the switch is acting as the source for a multicast stream so your WAN router is recording it correctly.

If you are trying to troubleshoot receiving multicast at the remote site then the above is not a valid test and tells you nothing.

What is the muilticast group address you are trying to join at the remote site ?

What does the mroute table show for that group address ?

Jon

 so if i were to ping multicast feed from lan with ip address of switch the edge router sees lan switch ip address as sender of feed...intresting :).... iam trying to joing 239.97.7.251....

But if that ping is not valid how else can i test whether branch is receiving feed or not ?

i suppose ping from RP or RP has always shortedt path tree from source anyway ?

morute does show (*,G) (*,239.97.7.251) entry  but OIL interface is Null and after pinging i was expacting it to be lan interface...RP is listed and so is rpf and correct incoming interface (wan)...ta

You need to send an IGMP join for that group so that your router knows it needs to request the stream from the RP.

What client are you using at the remote site ?

What is interesting is your router is showing a (*, G) entry which suggests something has at least requested the stream.

Can you post the out of the "sh ip mroute" for that group and also "sh ip pim rp" and "sh ip pim rp mapping".

Jon

we just used url that has several embedded links for multicast feed....user paste url in browser and then expact the feed....through that browse igmp request is sent...can you simulate igmp join request and send it from lan switch instead PC browser?....the only time i see (*,G) is when i send ping from lan to multicast ip address...

show ip mroute shows quite a few entry (IP's,G) when i do show ip route on them IP's they all coming from branch LAN...

show ip pim rp and show ip pim rp mapping for the 239 feed are pointing to same RP which is behind the Hub in the CORE.

and flag of show ip mroute is set to "spt bit set" and doesnt change from it when i do repeated show ip mroute...ta

You can temporarily use your router or switch if it is L3 to send an IGMP join request.

Don't know what you mean about the (<src IP>, G) entries all coming from the LAN ie. do you mean the incoming interface or OIL ?

I would have thought they should be coming from WAN.

Jon

all the swicthes are layer 3, i would google to see how send igmp join message....

By (src ip , G ) i mean when i start pinging feed address from lan switch i see multiple entries like below

(192.168.1.1, 239.97.7.251)

incoming interface LAN interface

Outgoing interface WAn interface

(192.168.2.1, 239.97.7.251)

incoming interface LAN interface

Outgoing interface WAn interface

its not right behaviour and maybe due to the fact tha when i send ping from lan its sends it everyone locally ....Ta

Pinging does not send an IGMP join, it generates it's own multicast stream.

You probably want to remove those entries from the mroute table.

Jon

I know pinging point just learnt from urself :)....i would simulate igmp join from switch and see what results i get ....checking now :) thanks alot for your help...

Sorry, I should have realised I had already explained that :-)

See what an IGMP join does and come back if it still isn't working.

Jon

Hi Jon

Sure, i would check and let yourself...thanks alot for your help :)

HI ...Just checked feed and only one is accessible....for other two the (*,g) entries are correct...s,g are correct as well...on LHR both OIL and IFF interface are correct ...flag for sg is T but no feed or url...and after few minutes s,g changes the correct OIL to NULL...

So for a multicast stream that doesn't work even though you see the correct entries in the mroute table you are not seeing any traffic on the client ?

Is that correct ?

Is this with a client sending an IGMP join or you doing it on the L3 switch ?

Might need some outputs but can you answer the above first.

Jon

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