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How to disable IP options send from router?

Hello all,

I've noticed my "core"-router is sending out IGMPv2 query packets with "Options" in the IP header (RFC2113). I can't find why this is happening nor how to disable it. I've read a lot of information how to discard packets with "Options" enabled, but not how to actually disable it if you are the source for these packets. Does anyone here has a clue?

Some more detailed information:

Switch: 4900M

IOS: 15.0(2)SG (cat44500e-ENTSERVICESK9-M)

IGMP querier using IGMPv2.

PIMv2 sparse-mode activated on all vlan's requiring multicast traffic.

My actual problem:

I've got Pilz Safety PLC's connected to a couple of vlan's which want to receive data from multicast group They don't support IGMPv2, but they do reply to an IGMPv2 query. However when the "options" field in in the IP header, they see the packet as a malformed packet (i know, that's not how they should responds according to RFC2113 but still they do..).

On another part of my network i don't have this problem. However, the "core"-router there is a 6500 with IOS 12.2.(33)SXI7. Interfaces, routing, IGMP and PIM are configured exactly the same.

I've attached two screenshots with both examples. Little note, from the screenshot showing the option field you will see two IGMP reports from the Pilz device to it's multicast group. This is correct because the device sends two IGMP reports when it's powering up. This is independent from IMGPv2 Query packets send from the router.

Thanks for your thoughts, support and time!

Kind regards,


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