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multicast

glen.grant
VIP Alumni
VIP Alumni

   Is there anything that would stop  a multicast transmission between 2 devices  on the same vlan . The scenario is 2 nokia 10I's one hooked to one 6509 sup 720 and the other on another 720 box both connected together with a etherchannel trunk .  Trunk is working fine between the boxes .  Spanning tree  for the vlan knows the root of the other box as primary  so layer 2 is working . Etherchannel and trunk working ok . All vlans allowed across the trunk between the 6500's .  These are setup as layer 2 only with a single address to manage the box .  Is it possible for these devices  not to talk in a simple setup like or is the issue with the nokias.   If they hook the nokias together on a single switch they say they talk ok .  Any ideas why they wouldn't talk across a layer 2 vlan ?

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Accepted Solutions

glen.grant wrote:

I think the boxes have enterprise services running 12.2.18 SXF17 .  Not at work right now .  don't know what multicast address the nokias use .  May have to do some searching around.

Glen

I think the issue you are seeing is to do with having IGMP snooping configured but nothing making the IGMP queries ie. you haven't got PIM enabled on a L3 vlan interface and you haven't specifically enabled the IGMP snooping querier function, see this doc for more details -

Multicast not working same vlan

The 6500 default config with your IOS is IGMP snooping is enabled but the IGMP snooping querier function is not enabled. There are a number of ways to fix this as outlined in the above doc -

1) static multicast mac-address entries

2) enable PIM on the L3 vlan interface so IGMP queries are sent out

3) If the switch supports it enable the IGMP snooping querier function

4) disable IGMP snooping - makes multicast broadcast

I would go with 3) as the 6500 supports the IGMP snooping querier feature -

6500 IGMP snooping querier

Jon

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10 Replies 10

burleyman
Level 8
Level 8

I guess it could be getting pruned off. I am a little new to troubleshooting this but could it have to do with configuring PIM. Like

ip pim {dense-mode | sparse-mode | sparrse-dence-mode}

Mike

glen.grant
VIP Alumni
VIP Alumni

  Is there anything that needs to be configured if they are just talking at a layer 2 level on the same vlan ?  HSRP which uses multicast needs no config to work .

glen.grant wrote:

  Is there anything that needs to be configured if they are just talking at a layer 2 level on the same vlan ?  HSRP which uses multicast needs no config to work .

Glen

No, you shouldn't have to configure anything although be aware that without an IGMP querier multicast packets with the same vlan are simply treated as broadcast.

Do you know -

1) whether IGMP snooping is enabled ? probably will be by default

2) whether you have configured an IGMP snooping querier (if the switch supports it)

I'm assuming that the L3 vlan interface for your L2 vlan does not have PIM configured on it ?

Jon

glen.grant
VIP Alumni
VIP Alumni

Hi  Jon , no nothing for multicast was configured at all .   Supposedly this setup  worked on a older catos 6500 running 7.6.21 code before we replaced both boxes  about 3 weeks ago .  Same setup, both boxes tied together   with a etherchannel trunk allowing all vlans  , though I think we only had 2 links in the channel versus the current 4  links .  Would the channel load balancing algorithm have anything to do with anything ? We don't use multicast anywhere so we never configure anything for it .  I'm not sure what the nokias use multicast for probably just to talk between the master and slave.  There is no L3 SVI for this vlan.  This is really more of a dmz switch which is firewalled  off in  different L2 vlans .  One address on the box to manage it .

I think the boxes have enterprise services running 12.2.18 SXF17 .  Not at work right now .  don't know what multicast address the nokias use .  May have to do some searching around.

glen.grant wrote:

I think the boxes have enterprise services running 12.2.18 SXF17 .  Not at work right now .  don't know what multicast address the nokias use .  May have to do some searching around.

Glen

I think the issue you are seeing is to do with having IGMP snooping configured but nothing making the IGMP queries ie. you haven't got PIM enabled on a L3 vlan interface and you haven't specifically enabled the IGMP snooping querier function, see this doc for more details -

Multicast not working same vlan

The 6500 default config with your IOS is IGMP snooping is enabled but the IGMP snooping querier function is not enabled. There are a number of ways to fix this as outlined in the above doc -

1) static multicast mac-address entries

2) enable PIM on the L3 vlan interface so IGMP queries are sent out

3) If the switch supports it enable the IGMP snooping querier function

4) disable IGMP snooping - makes multicast broadcast

I would go with 3) as the 6500 supports the IGMP snooping querier feature -

6500 IGMP snooping querier

Jon

Thanks Jon , good page .  I think the option for L2 may be the answer too . Must be the older catos boxes handled multicast streams differently.

Wow way out of my league on this one...well I tried. Hope I did not stear you down the wrong path.

I think you can issue the  show ip mroute   command to see the multicast IP address that the Nokia uses....not 100% on that though.

Jon, thanks for the great links.....I now have my homework for tonight.... 

Mike

Jon Marshall
Hall of Fame
Hall of Fame

Glen

What IOS version are you running now ?

Do you know what the multicast address is that the Nokia's use.

Jon

glen.grant
VIP Alumni
VIP Alumni

  Finally got around to dealing with this.  The fix ended up being  turning off ip igmp snooping .  As soon as we did their nokias were able to talk via multicast.  Thanks for your help Jon,  great page answered the problem exactly.

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