IGMP on gig-E

[Bob Moore_1]

I have a system running 11.11 with a gig-E interface. It is broadcasting igmp packets and confusing the switch that it is plugged into. Which is also running igmp, but in silent mode. This looks like it is causing the system to stop accepting requests like telnet, ftp, ssh. I have another system that is running 100Mb, that also has the igmp protocol in it's /etc/protocols file but it is not doing any broadcasting of igmp packets. Is there something with Gig-E that is causing the broadcast of igmp packets? And if so can it be turned off?

thanks,
bob

[Ron Kinner]

IGMP is used by mrouted to see who else can multicast and who wants to listen to a broadcast. I expect the problem is that mrouted is running on one and not the other or that the IFF_MULTICAST flag is set on the gig interface. The command

mrinfo

is supposed to give you info on mrouted.

mrouted's config file is:

/etc/mrouted.conf

but:

"By default, mrouted automatically configures itself to forward on all multicast-capable interfaces, excluding the loopback "interface," that have the IFF_MULTICAST flag set. Therefore, it is not necessary to explicitly configure mrouted (that is, the mrouted.conf file need not exist), unless you need to configure tunnel links, change the default operating parameters, or disable multicast routing over a specific physical interface. "

You can stop it gracefully with:

kill -INT pid

where pid is that of mrouted.

Ron

[Bob Moore_1]

Ron,
Thanks for the suggestions. but i have found out some more info that might help. As I've looked at what you are talking about and it does not seem to be the case. mrouted is not running on the system. that's why i don't understand why it is even doing any igmp broadcasting. Let me explain exactly what we are trying to do. (Which is what i should have done before..sorry..:-) )

this system currently sits on the public lan. We need to move it to a firewall protected lan because it is going to be accessed by developers outside of the company. the system is broadcasting an igmp aliased mac address even now, but the switch doesn't seem to care. it just passes the traffic and keeps on going. It's when we put it behind a firewall that things go south. Apparantly, according to our network experts, once the firewall sees this igmp aliased mac address it recognizes it's not the systems true mac address and blocks the traffic. Hence, no telnet, ftp, ssh from the internal network out to that system. the way the system acts when it first comes up on this new network seems consistant with this senario. when the system comes up everything works great for about 5 minutes. then boom, everybody that is connected gets booted out and cannot get back in.

so...what i'm trying to figure out, since this is my first experience with igmp, and i'd never even heard of it till yesterday, is why is igmp broadcasting the nic's mac address aliased instead of the real mac address? And, how do i stop it when mrouted is not even running?

thanks alot for your help.

[Bob Moore_1]

More info:

this is the message that is being spit out by the 6509 switch:
%MCAST-2-IGMP_ADDRAL:IGMP: Address Aliasing for 01-00-5e-00-00-01
%MCAST-2-IGMP_FALLBACK:IGMP: Running in FALL BACK mode

According to cisco's docs this is the solution:
The resolution is to use a sniffer to identify the host sending this traffic and isolate the host that is generating this type of multicast traffic. Verify which address is getting aliased; try not to use this address for the multicast data feed.

Here is the link to cisco's docs:
http://www.cisco.com/warp/public/473/180.html#subtopic1g

does anybody know if this is really an hp problem or a cisco problem?

[Ron Kinner]

Are you running gated? It does some multicasting too.

However, it sounds like a patch issue. Go to:

http://www1.itrc.hp.com/service/patch/mainPage.do

and select HP-UX then type in multicast or igelan and see what comes up.

Another possibility is that you could turn off the multicasting in the igelanconf (hpigelanconf?) file or perhaps in netconf.

Don't have a single HPUX up today. We are in the process of moving to a new location.

Ron

[Bob Moore_1]

Hi Ron,

I've searched for patches as well. i have all the patches that are needed for ige lan and the latest ARPA Transport patch. I've also looked in both those files but see nothing to change to turn off/on mutlicasting.

[John Payne_2]

Bob,

Did you ever get a resolution to this problem? I am also seeing the same thing as you did.

You're not running PeopleSoft, are you? That seems to be the only place I see it happening...

Thanks
John