Multicast and DA reject

Robert_74

Can someone point me in the right direction please ?

I have got laptop connected to j2300 (9.3R4.4) with VLC streamer. Packet count is incremented as per setup, but seems like all multicast traffic get discarder so I do not see anything with #monitor traffic interface ..

With traffic statistic I can see the counters, the most intresting ones are these:
Packet reject count 12408 [18]
DA rejects 12408 [18]

Juniper documentation states that DA rejects can be due to the multicast not being enabled ( ??) or bad arp entries on far end system
The funnies thing is that it works perfectly with vmware !!!

Having spent almost a day with this stuff finally realised I am almost exactly where I started so any help please would be appriciated

Thanks

Aldur

hmm... yea, multicast is always tricky, interesting to hear that it works in vmware. I'm guessing that it's not a config issue for this reason.

For the DA rejects do you know what the destination MAC is for the multicast traffic? I've seen this in the past when the program that is generating the traffic is sending it out with the incorrect dst MAC.

Robert_74

hmm, a bit strange all this .. Destination MAC, I have seen it on vmware ( 232.1.1.1 = 01:00:5e:1:1:1 ) Was unable to see on Juniper for that DA reject reason, p2p or multi access does not matter still the same result
Also tried to use Nortel's mchammer ( very nice application) but no joy here
It has to be something on a box, just can't figure out what ?

Very confused by the wording 'multicast routing is not on' - I assume it is always on with Junos

Aldur

enabling multicast routing in JUNOS is as simple as enabling PIM. So if you have PIM enabled then you have multicast routing enabled.

You do have PIM enabled on the FE interface on the J that you have your laptop connecting to, right?

Robert_74

tried with pim and dvmrp ..
Also tried on 3 different j23x0, same story
I can see all other mcast related stuff like ldp, ospf, igmp, pim etc, but not the generated traffic - bloody simulator catches everything with no problem. It drives me mad

Aldur

I still think it's the DA MAC that is giving you the problem. I get the same thing at work with a M320 using a Spirent traffic generator if I have the wrong DA MAC set for the stream. Keep in mind that the DA MAC should be the MAC of the interface of the first hop router.

Is there anyway you can check to see what the DA MAC is when the stream leaves your laptop? I'm not to familiar with VLC's multicast streaming abilities but you could run wireshark on your laptop to sniff what the DA MAC is.

Robert_74

Thanks Aldur, I think I give up on this occasion, just can not solve this puzzle. Will use cisco as last hop router instead

Robert_74

Problem ( if there was a problem) solved !

Decided to check it out on T series and the same picture -you can not see multicast traffic from directly connected source, and it appears to be the correct behaviour
What confused me was the fact that you can see it on vmware olives, but not on live box

Thanks everyone, topic closed

Aldur

heh, yet another reason why real boxes are always good to have on hand

One quick question though, are you still seeing the DA rejects incrementing?

Robert_74

Aldur wrote: »

One quick question though, are you still seeing the DA rejects incrementing?

Yes, but I believe they got nothing to do with multicast though.
Sometimes the mix of real and virtual environment can produce very weird results which makes thing in a way they are not supposed to be ..
I guess I relied on and trusted vmware too much doubting the real hardware

RabeenZhu

Hi Robert 74, please check your email or your private message box