Solved

Network Problem - IGMPv2 Storm

Posted on 2016-10-07
16
50 Views
Last Modified: 2016-11-13
Hi all,

We are currently suffering from an IGMPv2 storm on our network on a single VLAN across multiple HP switches. Wireshark records over 2000000 IGMP packets within a few seconds. Unsurprisingly clients are unable to get network access while this is happening. We have roughly 50 WAP's on this VLAN and some client PC's. I'm struggling to tell which WAP / client is causing the issue as the traffic all seems to relate to the clients responding to the IGMP packets. I don't know how to work out which one is causing them to all respond.

A snapshot of the wireshark log is attached. The destination address's appear to be multicast and can be 224.0.0.252, 224.0.0.2 or 224.0.0.113

I've tried physically unplugging switches one by one to try and work out which one has the offending client but I can't get a definitive answer. I assume because packets are moving throughout the network. When I do this the storm will "calm down" but be back within a few hours.


Any help in working out what's going on would be greatly appreciated.


Max.
Wireshark-Conversation-Snapshot.PNG
Wireshark-Snapshot-IGMP.PNG
0
Comment
Question by:stmonica
  • 5
  • 5
  • 4
  • +1
16 Comments
 
LVL 45

Expert Comment

by:Craig Beck
Comment Utility
Is IGMP snooping configured? It doesn't sound like it.
0
 
LVL 61

Expert Comment

by:gheist
Comment Utility
If you google for those IPs - it must be Cisco routers chatting.
IGMP is normal network traffic if you use multicast.
0
 
LVL 45

Expert Comment

by:Craig Beck
Comment Utility
It's PIM traffic. Can you post the switch configs?
0
 
LVL 61

Expert Comment

by:gheist
Comment Utility
Switches dont do PIM talk. It is routers.
0
 
LVL 45

Expert Comment

by:Craig Beck
Comment Utility
Layer 3 switches do, and other network devices (such as routers) do. The configs will help us to understand what the network looks like.
0
 
LVL 61

Expert Comment

by:gheist
Comment Utility
Layer 3 is not switches. It is a router.
0
 
LVL 61

Expert Comment

by:gheist
Comment Utility
0
 
LVL 39

Expert Comment

by:noci
Comment Utility
Destination is Multicast (ie subscribers).
The source address is where is comes from.
1
How to run any project with ease

Manage projects of all sizes how you want. Great for personal to-do lists, project milestones, team priorities and launch plans.
- Combine task lists, docs, spreadsheets, and chat in one
- View and edit from mobile/offline
- Cut down on emails

 
LVL 61

Expert Comment

by:gheist
Comment Utility
Souce MAC should be traceable.
0
 
LVL 45

Expert Comment

by:Craig Beck
Comment Utility
Gheist, why are you arguing? Have you never heard of a layer3 switch?
0
 
LVL 39

Expert Comment

by:noci
Comment Utility
A layer 3 switch more or less is a router bolted onto a switch. And layer-3 is by definition where routing takes place.
So there is no need for arguing by any one. A L3 switch also does everything a L2 switch does, it has to as part of the stuff in networks is done on L2.
1
 
LVL 45

Expert Comment

by:Craig Beck
Comment Utility
Exactly my point, noci. I don't understand the confusion.

I've asked for configs to see whether the switches are configured for snooping, amongst other things. Can we see configs please, stmonica?
0
 
LVL 39

Expert Comment

by:noci
Comment Utility
Now on IGMP....

An IGMP membership announcement is done (a few times to be sure, on a lossy protol like UDP)  when a multicast port is opened on a computer (host), indicating to an upstream router (and possibly switches [ IGMP-Snooping ] ) that it wants to receive multicast traffic.  The Leave is sent when the port is closed.
(A router that manages Multicast traffic can then selectively pass on Multicast traffic, same for switches that do IGMP-Snooping that can select to only forward to ports that need it in stead of all ports). So snooping is a performance option, where systems not interested in multicast will not get the traffic as well.

Is there software active that only runs for short times that happens to use multicast traffic? That can explain a lot of enter/leave group messages.
The other option is that you run a farm of systems that use multicast:  to address 224.0.0.113?
At least the systems *.48, *.31, *.32, *.33, *.34 and *.35 are active on that channel.
The 224.0.0.2 traffic is an indication of the amount of announcements.. for IGMP, for the number of times ports are closed. The opens should be to the whole group all hosts.
Due to it's nature Multicast is meant for longer duration of massive amounts of traffic from one source to multiple subscribers.
(TV & Radio broadcast are equivalent technologies).

224.0.0.2 - is All Routers... (As such it can be used to announce a host that is interested on the network. So PIM in a router can take note of the registration).
224.0.0.113 used to be used by the ALLJoyn framework, but shouldn't be now. as it also uses the mDNS group for that.
0
 
LVL 39

Expert Comment

by:noci
Comment Utility
btw. 1Mbps seems a lot, but is roughly 0.1% of a 1Gbps line.
0
 

Accepted Solution

by:
stmonica earned 0 total points
Comment Utility
Enabling DHCP snooping crashed the switches almost instantly. The problem turned out to be a bug in the firmware of a TP-Link access point connected to the network. Upgraded the firmware and the issue is no longer present.
0
 

Author Closing Comment

by:stmonica
Comment Utility
other comments did not resolve the issue.
0

Featured Post

Free Trending Threat Insights Every Day

Enhance your security with threat intelligence from the web. Get trending threat insights on hackers, exploits, and suspicious IP addresses delivered to your inbox with our free Cyber Daily.

Join & Write a Comment

Even if you have implemented a Mobile Device Management solution company wide, it is a good idea to make sure you are taking into account all of the major risks to your electronic protected health information (ePHI).
If your business is like most, chances are you still need to maintain a fax infrastructure for your staff. It’s hard to believe that a communication technology that was thriving in the mid-80s could still be an essential part of your team’s modern I…
Viewers will learn how to connect to a wireless network using the network security key. They will also learn how to access the IP address and DNS server for connections that must be done manually. After setting up a router, find the network security…
After creating this article (http://www.experts-exchange.com/articles/23699/Setup-Mikrotik-routers-with-OSPF.html), I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…

772 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

12 Experts available now in Live!

Get 1:1 Help Now