Wireless Access

A few months back we created a new profile and our WAN link got sturated to the point that only about half our users could connect. We found out it was multicast traffic and enabled bcmc-optimization on the VLAN. Well now we need some mutlicast traffic. I can easily remove the bcmc-optimization command but then the link will get saturated again.

 

Any ideas?

 

Thanks in advance

In 6.4.x there's a new functionality that allows you to drop Unknown multicast but it still allows you to receive known multicast if IGMP is enabled

We are on 6.2.1.7 so a jump to 6.4 won't happen in the immediate future, this feature would defintely help facilitate that though.

What is the nature of the multicast traffic?

It is Nortel Symposium RTD. It is a real time display of call agents status that gets disaplyed in a web browser. 

Hi johnnykilo,

 

To follow up on what Colin is alluding to, do you have a potential loop in your network? I was working with a client and they had a loop and a rogue device on their network flooding Multicast traffic. They had to go through the various switch stacks and look at the interfaces statistics on their switch. They were able to track down the rogue device and also figure out which switch stack had a loop doing this method.

 

It took some time, but it was well worth it as they were able to remove the BC/MC optimization on their controller VLANs.

 

-Mike

I would be very surprised if it was a loop. We don't have issues anywhere else that would support it.

 

This all happened when we changed our primary profile. Before we had one /24 network for phones and PCs (the PCs connect through the switchport on the phone) and the E1 port on the RAPs (LAN side) was trusted and no user roles were defined. I am trying to get confirmation that it was working before on this profile.

 

We ran out of IPs and divided the pool into 2 new /24 networks, 1 for phone and 1 for PCs. It all has to run on DHCP so we had to do some work. We trunked E1, untrusted it and set the native VLAN to 1000 (the PC VLAN). We enabled option 191 on the DHCP server which uses fingerprinting to ID the phone and tells it to initiate a new request in VLAN 1001 (phone VLAN). Also we set the default rule to authenticated and used a MAC based UDR to identify the phones and put them in the voice role. We were working fine for about a week with ~20 users on the profile. One night we moved over about 100 users and the circuit was pegged. We enabled BCMC on VLAN 1000 and the usage went backed to normal. 

 

We use about 20MB of the 100MB circuit for normal operation and under 5Mb for off hours, we were up over 75MB during peak utilization and around 20MB for non-peak once the new profile was in place.

I raised the loop to a senior guy on my team and he asked if PIM was on. I checked the running config and the 6.2 CLI reference and couldn't find much in the way of PIM. Does it run automatically in AOS 6.2.1.7 or does it need to be enabled?

http://www.arubanetworks.com/techdocs/ArubaOS_64_Web_Help/Content/ArubaFrameStyles/Mobility/Mobility_Multicast.htm

Thanks this is promising. If I am reading it correctly I could use SSM to define which multicast addresses I want the clients to be able to use. Am I correct? Does SSM act like an ACL for multicast?

Yes somewhat but unfortunately for you that functionality is on AOS 6.4.

Bah. Good to know though. This is a very valuable articale but it doesn't touch on PIM. 

I ended up creating a new VLAN and new AP Group and leaving BCMC oprimization off and that solved the issue.