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Inter-VLAN Multicast IP Routing using a 3560X Switch

Answered Question
Dec 27th, 2013
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Hello All,


I have a 3560x switch upgraded with the "ip services" license required to do IP multicast routing.  I could use some help with

this since I am having a difficult time on getting things to work correctly. 


I have attached two files; one of the block diagram and one with the configuration of the switch.  I am taking four separte serial input

data streams and converting them each to four separte multicast IP adresses: 239..1.1.3 thru 239.1.1.6.  These four are sent over a single

cable to the switch which I hoped I would be able to route the multicast data to two IP to Serial data conversion units.


These units have LEDs to show data activity but these will just not fire!


Please any help and commnents.


Thanks.


Regards,

Jeff

Correct Answer by Jon Marshall about 3 years 7 months ago

Jeff


The routing is done between source and receiver in terms of end devices. So if an end device is a receiver it doesn't then route the stream to another receiver.


if you want an end device to receive multiple multicast streams then that end device needs to register for all the streams it wants and the router will then send all streams to the end device.


Does that make sense ?


Jon

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John Blakley Fri, 12/27/2013 - 11:07
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Can you post "sho ip mroute"?



HTH,
John

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John Blakley Fri, 12/27/2013 - 12:22
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Jeff,


I see a couple of sources for the groups. It doesn't look like they're pruned, and I'm assuming that since you don't have an RP specified, you're using dense mode - also noted by the flags: DC. (The sparse-dense is only sparse if there's a known RP for the group.) As Jon mentioned, what's the ttl of the packet and is that configurable? Also, do you have members of this group?



HTH,
John

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Jeff Harned Fri, 12/27/2013 - 12:46
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Hi John


Please understand that I am learning as I go and what you mean by pruned and RP is unkwown to me.

Looking at the configuration to the switch that I attached earlier, I used the command "ip pim sparse-dense-mode for the SVI's.

As far as any configuration to the TTL levels this is also new to me and how do I measure this and if neccassary adjust this?


Not clear on what you mean about members; the four IP multicast Addresses that the serial data was converted to (4 separte serial inputs) are 239.1.1.3 thru 239.1.1.6


Thanks.


Regards,


Jeff

Jeff Harned Fri, 12/27/2013 - 12:30
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Hi Jon


That is a interesting question that I do not have an answer to or know how to check that.  Using Wireshark on the output cable from the Serial to IP Converter to the switch input (port 15) I see all three multicast data streams; 239.1.1.3 thru 239.1.1.6.

However, looking at the two outputs from the switch to the IP to Serial Converters (Receivers) to ports 1 & 2 there is no

multicast data at all.  I noticed this earlier but did not know what this indicates.


I attached the diagram and configuration that show the VLAN setups along with your request.


Thanks.


Regards,

Jeff

Jon Marshall Fri, 12/27/2013 - 12:36
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Jeff


Do you still have the wireshark capture. The TTL should be in there.


Jon

Jeff Harned Fri, 12/27/2013 - 12:52
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Hi Jon


I will have to set it up again and see if I can save it .


Thanks.


Regards,


Jeff

Jon Marshall Fri, 12/27/2013 - 13:01
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Jeff


You may be able to use the "debug ip mpacket" command which should show something like this -


R1#  debug ip mpacket 239.255.0.1 detail


   13:09:55.973: IP: MAC sa=0000.0c70.d41e (Ethernet0), IP last-hop=192.168.10.2

   13:09:55.977: IP: IP tos=0x0, len=892, id=0xD3C1, ttl=12, prot=17

   13:09:55.981: IP: s=133.33.33.32 (Ethernet0) d=239.255.0.1 (Ethernet1) len 906, mforward


but i would say you should only run this out of core hours as it can place a heavy load on the device


Jon

Jon Marshall Fri, 12/27/2013 - 11:13
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Jeff


In addition to John's request, do you know what the TTL setting is on the packets when they are converted to multicast. It needs to be greater than 1 as you need to route between vlans.


Which vlan is the source vlan and which vlan are the receivers in ?


Can you post -


1) sh ip igmp groups


2) sh ip igmp membership


Jon

Jeff Harned Tue, 01/07/2014 - 14:36
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Hi Jon


Been having a time with this but I happened to run into a document named  "Basic Multicast Troublshooting Tools".  One of the

commands is "show ip igmp interface" which did not give me the information as the example showed.  However, one of the comments that came back was the following that may lead to why this routing is not working, "Internet protocol processing

disabled".  Would you know what this means?


To answwer the question about the TTL, the source is set to 255.


Thanks.


Regards,


Jeff

Jon Marshall Wed, 01/08/2014 - 10:39
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Jeff


Can you post the config of the switch +


"sh ip int brief | include Vlan"


Jon

Jeff Harned Wed, 01/08/2014 - 12:29
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Hi Jon


I reconfigured with different IP addressses but still have the same result.  I am really having a time with this.   I included attached  files

with the drawing of the LAN and your requests. 


Thanks.


Regards,


Jeff

Jon Marshall Wed, 01/08/2014 - 13:04
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Jeff


Lets go through this step by step. So i need some outputs/IPs -


1) the serial to IP conversion unit. Does it have just one IP ? Can you post the IP


2) the IP to serial conversion units - what are their IP addresses. Actually lets concentrate on the one in vlan 10. What is it's IP


3) the unit in vlan 10, what stream should it be receiving ie. the multicast group address ?


It may be that the IP to serial units are not sending IGMP queries to the switch in which case the stream will not be sent into that vlan. Do you know if they support IGMP queries/replies ?


From the switch can you post the output of -


1) sh ip igmp groups


2) sh ip mroute


Jon

Jeff Harned Wed, 01/08/2014 - 14:15
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Hi Jon


Sounds like a good idea.  I will try to explain question by question.


Refering to the drawing from last post:

1) The four serial data streams comming into the Serial to IP converter were programmed to output muiticast addreses

of 239.1.1.3, 239.1.1.4, 239.1.1.5, and 239.1.1.6 with each one corrersponding to a single serial input.  These four multicast

data streams enter port 15 (VLAN 5) on the switch.  Using Wireshark confirms that all four multicast data streams are entering

the switch.  No other IP 's are being used except the ones to access the Converter unit to configure it to convert to the multicast addresses.


2) They are configured to be able to accept any one of the multicast addreses (above) at port 1 (VLAN 10) and

port 2 (VLAN 15). There are no other IP's asscociated with the ports. The only other IP's being used are the ones

to be able to access the IP to Serial units for configuration.


3)  It is configured now to recieve 239.1.1.3 and 239.1.1.4 simultaneously.  As far as know they do use IGMP but not sure which

version.


The ouputs requested are attached.


Thanks.


Regards,

Jeff

Jon Marshall Wed, 01/08/2014 - 14:21
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Jeff


2) The IP to serial convertors must have an IP address though eg. when they make an IGMP request or send a response they must use an IP to do this.


Do you know what they are.


3) Can you possible SPAN the port connected to the vlan IP to serial convertor to see if the multicast stream is actually being sent to it ?


Jon

Jeff Harned Wed, 01/08/2014 - 14:45
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Jon


Maybe this is the problem but I will have to do some further research on this.  I know the Converter units are not receiving any multicast data because all these unit have LEDs indicating receive or transmit activity and they are all out!!!  Wireshark

also confirms there is no multicast data.


I will have to research this and perhaps talk to someone who knows these converter units better than myself.  I will try

to post you tomorrow.


Thanks.


Regards,

Jeff

Jon Marshall Wed, 01/08/2014 - 14:29
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Jeff


What are the IP subnets being used for vlan 5 and vlan 10 ?


Jon

Jon Marshall Wed, 01/08/2014 - 14:36
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Jeff


I'm a bit confused by your outputs. From the switch config -


interface Vlan1

ip address 172.26.70.52 255.255.255.0

!

interface Vlan5

ip address 10.1.2.2 255.255.255.0

ip pim dense-mode

!

interface Vlan10

ip address 10.1.3.2 255.255.255.0

ip pim dense-mode

!

interface Vlan15

ip address 10.1.10.2 255.255.255.0

ip pim dense-mode

but from the "sh ip igmp groups"  -


cisco4#show ip igmp groups

IGMP Connected Group Membership

Group Address   Interface               Uptime   Expires   Last Reporter   Group Accounted

239.1.1.3       Vlan10                   02:10:58 00:02:40 172.26.7.30

239.1.1.2       Vlan5                   02:13:16 00:02:42 172.26.71.53

239.1.1.5       Vlan15                   02:09:32 00:02:42 172.26.71.28

239.1.1.4       Vlan10                   02:10:56 00:02:43 172.26.71.30

224.0.1.40       Vlan15                  00:12:16 00:02:45 10.1.10.2

all the reporters are using 172.26.x addressing but these are not the addresses being used for the vlan IP subnets according to your switch config ?


Jon

Jeff Harned Wed, 01/08/2014 - 15:13
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Jon


I am confused!!  The switch config I sent is correct.


The 172.26.71.30 address I am using to be able to talk to the  IP to Serial converter unit so I can configure it to receive

multicast addresses (data).  This unit is attached to port 1 of the switch.


The 172.26.71.28 address is used  for the second unit which is attached to port 2 of the switch.


The 172.26.71.53 is the address of one of the Serial to IP converter modules.  This is the the Eth port used to send one of the

the converted data with an multicast address of 239.1.1.3.


I do not know what 239.1.1.2 is; I am not using this adddress for any of the conversion processes.  What is 224.0.1.40?


Thanks.


Regards,


Jeff

Jon Marshall Wed, 01/08/2014 - 15:20
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Jeff

           

So from the switch can you ping 172.26.71.x addresses ?


If you can i'm not sure how this is working because none of your L3 vlan interfaces on the 3560 have a 172.26.71.x address.


I would expect the units to have IPs from the same IP subnets as the L3 vlan interfaces on the 3560.


Jon

Jeff Harned Thu, 01/09/2014 - 07:23
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Hi Jon


New day.


The only one I can ping is the xxx.xx.71.30


I appaerntly have a misunderstading on how to set up ports to pass multicast data.  I am uncertaian on how regular IP addressess interact

with the multicast addresess.


Ok, what I have done is to make another drawing that includes the ip addresses used .  As use can see the xxx.xx.70.xx ones are

used to access all the switches and converter units for configuration and management.  The xxx.xx.71.xx are used for all data flow.


Thanks.


Regards,


Jeff

Jon Marshall Thu, 01/09/2014 - 07:45
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Jeff


I don't uderstand why you are using 172.16.21.x addressing for the IP to serial convertors but the vlans they are in are using 10.1.x.x addressing.


Why can you not assign the IP to serial convertors an address out of the IP subnet used for the vlan they are in ?


Jon

Jeff Harned Thu, 01/09/2014 - 08:14
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        Jon


I can change the converters to anything I want.  This is part of the problem.   If we stick with 10.xx.xx.xx adresses that are configured on the switch

now, what addresses can I use on the IP to Serial converters?  


Also with port 15 (VLAN 5) on the switch with the four 172.xx.xx.xx addresses, corresponding to the four Serial to IP modules how would this port

be configured.  This is part of my issue, I do not understand the relationship betwee the 172.xx.xx.xx addresses and the four multicast addreses.

Again I can set this converter to whatever I want.


Thanks.


Regards,


Jeff    

Jon Marshall Thu, 01/09/2014 - 08:22
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edited

Jeff Harned Thu, 01/09/2014 - 12:34
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   Jon


Well some good news!!  The two receiving units are receiving multicast data at last!!  I have upgraded the last diagram that I sent you with

the updated IP addresses for you to look at and check if they are okay.   I still want to get to the point where I can route between the two VLANS and
I believe the configuration that I sent you yesterday is not correct to accomplish this.


Any comments on the next step to get to this point?


Jon, I appreciate all the help that you have provided!!   


Thanks.


Regards,


Jeff

Jon Marshall Thu, 01/09/2014 - 12:47
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Jeff


If the receiving units are getting the multicast stream does that not mean that routing between the vlans is working ie. the source of the multicast stream is on a different vlan than the receivers.


Can you specify what exactly still isn't working ?


Jon

Jeff Harned Thu, 01/09/2014 - 13:17
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       Jon


I am looking at this at another angle that may not be incorrect.  Both receivers are configured to each receive 239.1.1.3 and 239.1.15 simultaneously

which is verified through Wireshark and through the LED activity of both receiver units.


I was not perhaps looking at the routing between source and receivers in differnt VLANs but from receiver to reciever in different VLANS and routing

between them.  I am wrong with this?  Is it always Source to Receiver or can routing be done between Receiver Port A and Receiver Port B on a switch?


Thanks.


Regards,


Jeff

Correct Answer
Jon Marshall Thu, 01/09/2014 - 13:28
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Jeff


The routing is done between source and receiver in terms of end devices. So if an end device is a receiver it doesn't then route the stream to another receiver.


if you want an end device to receive multiple multicast streams then that end device needs to register for all the streams it wants and the router will then send all streams to the end device.


Does that make sense ?


Jon

Jeff Harned Thu, 01/09/2014 - 13:55
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         Jon


It does make sense and in fact that is actually what is happening in both receivers!!  They are both receiving the configured multicast addresses of 239.1.1.3

and 239.1.1.5.


Wow, looks like I have routing between VLANs!!


Jon, this has been an important issue with myself for such a long time now and now I should be able to expand from this point using multiple multicast sources.

I really do appreciate you hanging in there with me and teaching me some network workings!!!



Thanks.


Regards,


Jeff

Jon Marshall Thu, 01/09/2014 - 14:11
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Jeff


No problem, glad to have helped.


Jon

Jon Marshall Thu, 01/09/2014 - 08:25
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Jeff


I can change the converters to anything I want.  This is part of the problem.   If we stick with 10.xx.xx.xx adresses that are configured on the switch now, what addresses can I use on the IP to Serial converters? 


They would simply be assigned an IP from the subnet for that vlan assuming you have spare IPs.  So they would use 10.x.x.x addressing.


Also with port 15 (VLAN 5) on the switch with the four 172.xx.xx.xx addresses, corresponding to the four Serial to IP modules how would this port be configured.  This is part of my issue, I do not understand the relationship betwee the 172.xx.xx.xx addresses and the four multicast addreses..Again I can set this converter to whatever I want.

This is more tricky but if the port is assigned into vlan 5 then you should assign the serial to IP convertors with the corresponding 10.x.x.x addresses from that vlan.


Bear in mind that even though you are using multicast the IP routing table is still used and so it is important to have the right IPs configured.


I would try changing the convertors to use the respective 10.x.x.x addressing and see if that works. If it doesn't then at least we have ruled out something else.


Jon

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