Multicast over GRE between Linux server and Cisco Router
I am trying to set up multicast between a Linux server and Router using GRE. The GRE tunnel is up fine and I can see traffic go across it, but the router is not indicating it is receiving the IGMP joins that the server is sending. I have identical setting with another server attached to fastethernet0/1 and it is joined to the group fine, but I am not able to get the server to link to the router via GRE interface. Note that I have another server behind another router where the two routers do GRE and PIM and that on is working fine. Is there some reason that IGMP joins would not work across the GRE link, but another router using PIM would? -- Brian Christopher Raaen Network Architect Zcorum
My guess is that this is because IGMP is a host-to-router protocol while PIM is for router-to-router signaling. IGMP joins typically flow from a multicast receiver to its local router. A GRE tunnel emulates a router-to-router connection, so you need PIM running on it for signaling. An IGMP join is really just a first hop host-to-router message and isn't intended to be routed, which is what would be necessary to get it over a GRE tunnel. HTH, John On Wed, Jan 9, 2013 at 8:51 AM, Brian Christopher Raaen < mailing-lists@brianraaen.com> wrote:
I am trying to set up multicast between a Linux server and Router using GRE. The GRE tunnel is up fine and I can see traffic go across it, but the router is not indicating it is receiving the IGMP joins that the server is sending. I have identical setting with another server attached to fastethernet0/1 and it is joined to the group fine, but I am not able to get the server to link to the router via GRE interface. Note that I have another server behind another router where the two routers do GRE and PIM and that on is working fine. Is there some reason that IGMP joins would not work across the GRE link, but another router using PIM would?
-- Brian Christopher Raaen Network Architect Zcorum
Just a quick note. I do have multicast enabled on the server gre1 interface. A tshark capture shows the igmp group queries from the router and the igmp join reply from the server. On Wed, Jan 9, 2013 at 10:51 AM, Brian Christopher Raaen < mailing-lists@brianraaen.com> wrote:
I am trying to set up multicast between a Linux server and Router using GRE. The GRE tunnel is up fine and I can see traffic go across it, but the router is not indicating it is receiving the IGMP joins that the server is sending. I have identical setting with another server attached to fastethernet0/1 and it is joined to the group fine, but I am not able to get the server to link to the router via GRE interface. Note that I have another server behind another router where the two routers do GRE and PIM and that on is working fine. Is there some reason that IGMP joins would not work across the GRE link, but another router using PIM would?
-- Brian Christopher Raaen Network Architect Zcorum
-- Brian Christopher Raaen Network Architect Zcorum
IGMP packets are sent with TTL=1. Is the tunnel interface on the router enabled for PIM? Tom On Fri, Jan 11, 2013 at 5:11 AM, Brian Christopher Raaen < mailing-lists@brianraaen.com> wrote:
Just a quick note. I do have multicast enabled on the server gre1 interface. A tshark capture shows the igmp group queries from the router and the igmp join reply from the server.
On Wed, Jan 9, 2013 at 10:51 AM, Brian Christopher Raaen < mailing-lists@brianraaen.com> wrote:
I am trying to set up multicast between a Linux server and Router using GRE. The GRE tunnel is up fine and I can see traffic go across it, but the router is not indicating it is receiving the IGMP joins that the server is sending. I have identical setting with another server attached to fastethernet0/1 and it is joined to the group fine, but I am not able to get the server to link to the router via GRE interface. Note that I have another server behind another router where the two routers do GRE and PIM and that on is working fine. Is there some reason that IGMP joins would not work across the GRE link, but another router using PIM would?
-- Brian Christopher Raaen Network Architect Zcorum
-- Brian Christopher Raaen Network Architect Zcorum
-- ----------------------------------------------------------------------------- Tom Ammon Network Engineer M: (801) 674-9273 tom@tomsbox.net -----------------------------------------------------------------------------
From my experience, it seems most Linux multicast development has stalled significantly in recent years.
None the less, look for something called "smcroute". You should be able to use this to manually peg up a route and generate the join. Also take a look at the output of netstat -n -g to see the join. igmpproxy is also good if this is a stub network and you're trying to proxy joins. Let me know what ends up working for you. I've fought this one once already. I never did like the results, but I ended up using the igmp proxy method. On Fri, Jan 18, 2013 at 8:07 PM, Tom Ammon <thomasammon@gmail.com> wrote:
IGMP packets are sent with TTL=1. Is the tunnel interface on the router enabled for PIM?
Tom
On Fri, Jan 11, 2013 at 5:11 AM, Brian Christopher Raaen < mailing-lists@brianraaen.com> wrote:
Just a quick note. I do have multicast enabled on the server gre1 interface. A tshark capture shows the igmp group queries from the router and the igmp join reply from the server.
On Wed, Jan 9, 2013 at 10:51 AM, Brian Christopher Raaen < mailing-lists@brianraaen.com> wrote:
I am trying to set up multicast between a Linux server and Router using GRE. The GRE tunnel is up fine and I can see traffic go across it, but the router is not indicating it is receiving the IGMP joins that the server is sending. I have identical setting with another server attached to fastethernet0/1 and it is joined to the group fine, but I am not able to get the server to link to the router via GRE interface. Note that I have another server behind another router where the two routers do GRE and PIM and that on is working fine. Is there some reason that IGMP joins would not work across the GRE link, but another router using PIM would?
-- Brian Christopher Raaen Network Architect Zcorum
-- Brian Christopher Raaen Network Architect Zcorum
--
----------------------------------------------------------------------------- Tom Ammon Network Engineer M: (801) 674-9273 tom@tomsbox.net
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