Multicast trafficis being flooded on igmp snooping enabled switch

I have two devices connected to the same switch, S streams video using multicast, H doesn't send join request, but the multicast is being sent to H, actually it is being flooded. Both hosts are in the same vlan.
Distribution-1#show ver | in WS
cisco WS-C2960-24TT-L (PowerPC405) processor (revision E0) with 65536K bytes of memory.
Model number : WS-C2960-24TT-L
* 1 26 WS-C2960-24TT-L 15.0(1)SE2 C2960-LANBASEK9-M

Duplicate post.
Go here: https://supportforums.cisco.com/discussion/12218811/multicast-trafficis-being-flooded-igmp-snooping-enabled-switch

Similar Messages

Which is prioritized for multicast traffic if FastSwitching and CEF is enable?

Hello
Here is the related configuration and output of show command below,
In my understanding, there are 3 swtching mode, CPU, fast-swthing and CEF swthing,
But if FastSwthing and CEF swithing are enable both, then which swithing mode is prioritized for mutlicast traffic?
interface Vlan302
ip address 10.0.20.1 255.255.255.0
3750X#sh ip int vlan 302
Vlan302 is down, line protocol is down
Internet address is 10.0.20.1/24
Broadcast address is 255.255.255.255
*omit
IP fast switching is enabled
IP Flow switching is disabled
IP CEF switching is enabled
IP CEF switching turbo vector
IP Null turbo vector
IP multicast fast switching is enabled
IP multicast distributed fast switching is enabled
IP route-cache flags are Fast, CEF
*omit
interface Vlan301
ip address 10.0.10.1 255.255.255.0
no ip mroute-cache
3750X#sh ip int vlan 301
Vlan301 is down, line protocol is down
Internet address is 10.0.10.1/24
Broadcast address is 255.255.255.255
*omit
IP fast switching is enabled
IP Flow switching is disabled
IP CEF switching is enabled
IP CEF switching turbo vector
IP Null turbo vector
IP multicast fast switching is disabled
IP multicast distributed fast switching is disabled
IP route-cache flags are Fast, CEF, No Distributed
*omit
Product : Cat3750X
IOS version : 15.0(2)SE5
Best Regards,
Masanobu Hiyoshi

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I'm not 100% certain, but I believe FastSwitching and CEF switching apply to unicast, not multicast. Your "IP mroute-cache" command enables/disables fast multicast switching.
On a 3750, switching should be hardware based, for unicast and multicast, unless TCAM resources are insufficient. If hardware switching falls back to non-hardware switching, you'll likely find process vs. Fast vs. CEF vs. multicast doesn't matter, all too slow.

IGMP Snooping in Switch Hierarchy

Hello,
I have a question regarding IGMP when more than one switch is between mcast router and the hosts.
My setup is as follows:
mcastrouter1
|
Core1
| \
| Access-Switches (several) - hosts
| /
Core2
|
mcastrouter2
The core-switches are cat6k (native), the access-switches a mix of cat3550 and cat4506.
The mcast routers are connected to the core switches, the hosts connect to the access switches. IGMP Snooping is enabled on all switches.
On the core switches I see the IGMP entries in the MAC table just fine, but they somehow seem not to arrive at the access-switches. We tried all the debugs we can think of, but we cannot see any IGMP messages arriving at the access switches, where the hosts are connected. The mcast routers and the hosts are in the same VLAN. This VLAN is configured on the core and the access switches. One of the core switches is the STP root.
The trunks between the core and the access switches are dot1q trunks over glas links. All switches use 12.1 software.
Is this behaviour works-as-designed? I would expect that the IGMP messages are flooded throughout the VLAN, and this is terminated on the access switches. So the access switches should see the messages as well. Our tests tell us that the IGMP messages do not make it to the access switches. I cannot see why the switch should filter the message, because it should be forwarded to the hosts in any case.
Every document I checked on CCO has always one switch between the mcast router and the host.
If anyone has any tips or documents that may help me, I would really appreciate it.
Thanks
-birgit

Hi,
Not sure if this helps much but we are using CGMP in our environment as we have lots of legacy switches at the moment.
I can see lots of CGMP join messages throughout the layer2 switches and would expect to see the same for IGMP
2005 Aug 04 09:27:09 GMT +00:00 %MCAST-6-RX_CGMPJN:CGMP: Rcvd CGMP Join Mesg vla
n 20
2005 Aug 04 09:27:09 GMT +00:00 %MCAST-6-RX_CGMPJN:CGMP: Rcvd CGMP Join Mesg vla
n 40
2005 Aug 04 09:27:09 GMT +00:00 %MCAST-6-RX_CGMPJN:CGMP: Rcvd CGMP Join Mesg vla
n 40
2005 Aug 04 09:27:10 GMT +00:00 %MCAST-6-RX_CGMPJN:CGMP: Rcvd CGMP Join Mesg vla
I'm looking for a switch that supports IGMP so i can enable snooping and see what happens and will report back.
Thanks
Paddy

Multicast traffic flooding

Hi
We are using Network Load Balancing on some Windows 2003 servers which is configured as IGMP multicast.
The servers are connected to a 3550 SMI switch which is connected to a HP4108.
Before I configured either of these switches I connected a packet sniffer and saw the multicast traffic appearing on all ports on both switches.
I configured the HP switch as a Multicast querier and now on the 3550 I see the multicast mac addresses logged against the server ports. The 3550 also detects the muticast router as you can see:
prod-3550#sh mac-address-table mult
Vlan Mac Address Type Ports
1 0100.5e7f.4601 IGMP Fa0/10, Fa0/12, Gi0/1
1 0100.5e7f.4602 IGMP Fa0/9, Fa0/11, Gi0/1
prod-3550#
prod-3550#sh ip igmp snoo mrouter
Vlan ports
1 Gi0/1(dynamic)
The 3550 is still spamming the multicast traffic to all ports whereas the HP switch is only replicating thisto ports that are part of the multicast group.
Can anyone tell me why the 3550 is doing this or what else I need to check?
Thanks in advance.

Kate
You do not tell us much about how the 3550 is configured. From your description of the problem I am going to assume that you do not have IGMP snooping configured. This link will show you how to configure IGMP on the 3550:
http://www.cisco.com/univercd/cc/td/doc/product/lan/c3550/12225sec/3550scg/swigmp.htm
If my assumption is not correct and you do have IGMP snooping configured, then you will need to tell us more about how the 3550 is configured so we can determine why it is propagating multicast to all ports.
HTH
Rick

IGMP Snooping configuration for Multicasting on Cisco Catalyst 3020

IGMP Snooping configuration for Multicasting on Cisco Catalyst 3020
Hi Guru,
Our switch model is "Cisco Catalyst Blade Switch 3020 for HP"
We are building HA (High Availability) Databases infrastructure.
Currently, there are two nodes(hosts- servers) and two above switch for HA.
Oracle said we need to turn off the IGMP Snooping in order to use the multicasting for their interconnect communication.
So my question is:
Q1> Is there any way to use Multicasting without turning off IGMP Snooping on Switch side?
Q2> If 'yes', how can we configure the switch for Multicasting ?
Oracle uses 230.0.1.0 & 224.0.0.251 IPs with 42000 range port for Multicasting communication.
Please shed some light on it

May I request if you avoid making multiple posts of the same issue? This will only confuse people (including you).

SRW208: IGMP Snooping not working!

Hi all,
at the moment we have trouble with the following SRW208 setup:
- Port mirroring is enabled (Port 8 mirrors Port 1) for sniffing via Wireshark in promiscuous mode.
- 'IGMP Snooping' is enabled for all ports.
Our test scenario:
- an IPTV settop-box is connected to port 1 and gets/sends traffic from/to a VDSL router connected to port 2.
- a wireshark PC sniffs at mirror port 8 (all traffic) in promiscuous mode
- another wireshark PC sniffs at port 3 (all traffic) in promiscuous mode
With IGMP snooping enabled only the wireshark PC at (mirroring) port 8 should be able to sniff the mcast traffic between the settop-box and the VDSL router.
The problem is that wireshark can sniff the mcast traffic at all ports. In addition the LED of all active ports are blinking synchronously/continuously.
It seems that the IGMP snooping does not to work properly because all ports are still flooded with mcast traffic.
With an old Zyxel switch the same setup works without a problem.
Is this a known problem of the srw208?
Cheers,
Fred

So much for the image upload, how about this diagram:
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Spirent 3 --------------| SRW2008 |------------------ Spirent 4
                            |                   |------------------ Spirent 5
                            |                   |------------------ Spirent 6
                            |                   |------------------ Spirent 7
                            |                   |------------------ Spirent 8

IGMP snooping functionality on apple time capsule & extreme

Hi,
I use an apple time capsule which has 7.7.3 version in it. There is an option in apple capsule to enable or disable IGMP snooping,
Does apple capsule disables forwarding multicast packets on disabling IGMP snooping?
On wire-shark, I can see an IGMP query message is going out of apple capsule on enabling "IGMP snooping" and there is no IGMP query message from apple capsule when IGMP snooping is disabled. Based on IGMP V3 standard, a IGMP query is sent by router. On "IGMP snooping" disabled case, is it host's responsibility to forward multicast packets?
And I have an airport extreme as well which does not have IGMP snooping enable/disable functionality. How IGMP and multicasting works on this?
Thanks

And I have an airport extreme as well which does not have IGMP snooping enable/disable functionality. How IGMP and multicasting works on this?
What model and firmware is the extreme?
If you look under the wireless options in the 5.6 utility it shows multicast as preconfigured to on.. and set to low by default. you had the option to set higher if you wished with the result that more of the wireless bandwidth was reserved to handle multicast.
You might need to use the older utility if it is Gen5 or earlier as some functionality was simply removed in the v6 airport utility and never returned.
IGMP never rates a mention.
On wire-shark, I can see an IGMP query message is going out of apple capsule on enabling "IGMP snooping" and there is no IGMP query message from apple capsule when IGMP snooping is disabled. Based on IGMP V3 standard, a IGMP query is sent by router. On "IGMP snooping" disabled case, is it host's responsibility to forward multicast packets?
I cannot answer your specific question.. but is the IGMP set on by default?? If so I expect apple was thinking it should automatically handle the bandwidth demand whereas the older ones had issues with this and needed manual setting when using wireless. If you turn it off then multicast will have issues I am guessing.

Disabling ''igmp snooping'' in a VLAN (no interface VLAN) on Catalyst 6500

Can please some help?
On 4948 or 3560 I can disable igmp snooping in a specific VLAN:
sw4948(config)#no ip igmp snooping vlan ?
<1-1001>     Vlan number
<1006-4094> Vlan number
sw4948(config)#no ip igmp snooping vlan 10 ?
explicit-tracking           Enable IGMP explicit host tracking
immediate-leave             Enable IGMPv2 immediate leave processing
last-member-query-interval Last member query interval
mrouter                     Configure an L2 port as a multicast router port
static                      Configure an L2 port as a member of a group
<cr>
BUT, in 6509-E this command is not enabled:
sw6509(config-if)#no ip igmp snooping ?
access-group IGMP group access group
limit         IGMP limit
I have just found on my 6509 that I can disable igmp snooping in a SVI interface (Interface VLAN)
sw6509(config)#int vlan 20
sw6509(config-if)#no ip igmp snooping ?
access-group                IGMP group access group
fast-leave                  Enable IGMP fast leave processing
last-member-query-interval Configure IGMP leave query timeout
limit                       IGMP limit
minimum-version             Minimum IGMP version
mrouter                     Configure an L2 port as a multicast router port
querier                     Enable IGMP querier processing
report-suppression          Force a report suppression
ssm-safe-reporting          Enable SSM Safe Reporting
static                      Configure an L2 port as a member of a group
<cr>
My current 6509-E IOS version is:
System image file is "sup-bootdisk:s72033-advipservicesk9_wan-mz.122-33.SXH8b.bin"
Do I need to upgrade my IOS version?... or how can I disable ''igmp snooping'' per specific VLAN (no Interface VLAN)?
Any help would be apreciated !
Regards
guruiz

Hi Guruiz,
So, to disable igmp snooping in some VLANs in the 6509, do I need to disable it globally?
Would it be the only way?
That appears to be the only way. If you have an SVI for the vlan you want to run Multicast in, then simply enable PIM and not worry about IGMP snooping. I think, the reason you don't see this command under the layer-2 vlan is because most of the time the 6500 is used as layer-2/layer-3 and not just layer-2.
How could "no ip igmp snooping" applied globally impact my 6509 switch?
It will impact only the vlans that are running Multicast. In general, ip IGMP snooping is used when you have a flat vlan and no SVI. If you have multiple vlans and are running Multicast between them, then you can just enable PIM.
HTH

Multicast Traffic - IGMP Snooping

We are currently running a Hybrid CATOS/IOS Environment with Sup2 and MSFC2 Line Cards. The Sup Version is
8.4(3) and MSFC is 12.1(26)we want to run multicast traffic between our internal network to our external Govt Provider in the form of a particular Video Conferencing Client. We have been told that seeing we are running CATOS on our Sup2 engines we will get periodic dropouts of multicast traffic between our internal and external Depts if we don't upgrade to an Native IOS Environment. They are saying that we cannot disable igmp snooping on a per-Vlan basis under our Current Hybrid Environment unless we upgrade to Native IOS. Can we disable igmp snooping on a per-vlan basis using our current CATOS version or do we have to upgrade to a Native IOS Software set ??
Thanks Simon

at the catOS level, you only have the ability to enable igmp, not per vlan.
on the msfc SVIs you should then be able to enable or disable igmp at the VLAN interface level.
this may provide the abilities you are looking for.
try this and let us know if any further issues or post your config for review.

Multicasting (IGMP Snoop) between Nortel and Cisco

We are currently having issues with Zen imaging (multicasting) and our setup is the following.
Please take into account, our knowledge is very limited with IGMP Snooping setup etc.
MDF = 6 Nortel 450-24T's using FirmWare -1.48 / SoftWare - 4.5.2.4
IGMP Settings are such :
VLAN: [ 1 ]
Snooping: [ Enabled ]
Proxy: [ Disabled ] -----> This was on...but once off, runs much smoother.
Robust Value: [ 2 ]
Query Time: [ 125 seconds ]
Set Router Ports: [ Version 1 ]
In the MDF (anythig directly in those switches) images fine now. (once I disabled PROXY)
However I have a few IDF's off the MDF that are using OLD Nortel 350F-HD's (no IGMP Snooping support) and it's horrible (can only do a few computers at a time.
So in one of the IDF's (the biggest one) I pulled out the 350F-HD and replaced it with a CISCO 2950 w/Fiber and it's using 12.1.20EA1 and I left IGMP Snooping on (thinking this will fix it) and couldn't even get ONE machine to connect and image in the multicast session. It's settings were (by default):
Global IGMP Snooping configuration:
IGMP snooping : Disabled
IGMPv3 snooping (minimal) : Enabled
Report suppression : Enabled
TCN solicit query : Disabled
TCN flood query count : 2
Vlan 1:
IGMP snooping : Disabled
Immediate leave : Disabled
Multicast router learning mode : pim-dvmrp
Source only learning age timer : 10
I then completly disabled IGMP Snooping on the CISCO and we're able to Image 5-7 Computers without a crash (more than that and it crashes - disconnects etc)
In the area's that I have All 450's or all CIsco's the imaging seems to go fine. (with minor errors)
Can any one give me some advice (or hopefully ran into this mixed setup before)?
Thank you.

Bosalaza,
Thank you for replying (and I read even more on the ip multicast routing). However I've not ran into the same issue at any school that has 100% cisco switches or 100% Nortels (that are setup correctly and not older than dirt). I think we've not needed the multicast routing setup as we only have one router on the network (and it's flat at the moment anyway). As long as IGMP Snooping is enabled correctly (on the switches) it seems to serve us well.
Although from what I've read (where you pointed me too) it seems even in our setup we would benifeit from taking time to setup "ip pim ....." etc.
I was able to scrounge from another network and change out a few very old Nortels (that didn't support IGMP Snoop) and all seems well now.
So long story short (and incase anyone else needs this info. The Nortel 350T and F - HD's were the main issue. It seems (for now) that a mixture of Nortel 350/450-24T's (any model that at least has IGMP Snooping) and Cisco's mixed (also Snoop on) works pretty well.
I'm going to consider this solved as I was able to fix it with changing out some old product. However I really appreciate your efforts and pointing my towards some good info. (Which I'm going to read up on more, as I'm sure we'll need to get it setup in the near future.)
Thanks again.

How to configure SFE2000 to filter multicast (IGMP is enabled)

We have a SFE2000 switch and we're having trouble configuring IGMP snooping. It is enabled but we are still seeing multicast traffic on ports which have definitely not done an IGMP join - indicating something is not right. The literature on the switch says it supports IGMP snooping. Can anyone advise or point me to a technical resource? This switch is part of a standard package and we are looking at alternative suppliers since this switch is not doing what we need. I'd like to confirm this switch can't do what we need or understand how to properly configure it before going elsewhere. I have reviewed the manuals. I suspect the issue relates to configuring a multicast querier. I don't see a way to do this on the SFE2000. Our system is isolated so the SFE2000 is not connecting to a higher level switch. The SFE2000 needs to act as the querier. Thanks in advance for any help/direction. - Jim

The following two links are related and interesting :
http://www.plctalk.net/qanda/showthread.php?t=49905
http://forums.linksysbycisco.com/linksys/board/message?board.id=Switches&thread.id=3043
I'm not sure converting the SFE2000 to layer 3 will cause it to act as a querier or not.

Multicast mac address isn't learned, igmp-snooping

I have PIM router which connects to the cat 2960 switch and also I have host which connects to another port on the same switch. Host was joined to the IGMP group 224.1.1.1. I see that the router generates igmp-query and the host respons. IGMP-snooping process sees that process and updates appropriate entries:
2960-5#sh ip igmp snooping mrouter
Vlan ports
15 Gi2/0/32(dynamic)
2960-5#sh ip igmp snooping groups
15 224.1.1.1 igmp v2 Gi2/0/32, Gi2/0/33
But when I command "sh mac address-table multicast" I see nothing:
2960#sh mac address-table multicast
Vlan Mac Address Type Ports
What is reason of this problem?

There is the following statement from the "CCNP Practical Studies: Switching:
the process of populating the bridge table with multicast MAC addresses is based upon inspection of the destination MAC address, unlike unicast MAC addresses where the source MAC address of unicast frames is examined to generate bridge table entries.
And this book describes other parts of the mac learning process and says that after exchanging IGMP-message MAC-table must be populated by multicast mac-addresses. But later I found some Cisco and Jupiner documentation which says there is two way to perform multicast forwarding - MAC and IP. Default metod is IP multicast forwarding. When this metod is used multicast MAC-addresses isn't learnt and process of packet forwarding uses special forwarding cache which includes list of mapping IP and appropriate interfaces. It all means that this book isn't actual. All modern switchs perform multicast forwarding by IP metod and MAC-addresses don't populate CAM.

Ip igmp snooping querier?

i've been reading these forums and noticed that lot of people have problems with configuring multicast. basicly, problems are flooding bandwidth, no querier, confusing pim router configuration ...
also, ive seen some promisses from tehnical stuff that next gen of linksys switches will have #ip igmp snooping querier, like cat ones have. so i'm interested if someone can give me the answer.
it is interesting question for many people who would cant afford expensive cat switches for such simple usage.
regards,
david

Hi David,
You actually have a lot more options as seen in the GUI, so I though I would put as simple network together and run you through a validation.
But I am assuming you have the refreshed version of the SRW224G4P switch called the SRW224G4P-K9-NA .
If you have the old switch the following is not relevant to you.
I put together a simple network diagram showing my simple network topology used during my wee test;
I chose the RV042 as my Layer 3 router in this network.
It really was to provide DHCP services, but shortly after all devices had IP addresses, I removed the RV042, becauise I noticed it was sending out IP IGMP general queries.    Something I didn;t want in the following test.
I was using a software based multicast tester, produced by the wonderful folk at Twisted Pair Solutions. This software can either send and/or receive multicasts of a defined group and responds appropriately to IGMP General queries. I will call this software MCT (Multicast test).
I had the MCT software on PC C. PC C is plugged into switch port 10 It is sending multicasts into the switch at a rate of about 10 multicast packets a second.
I had the MCT software on PC A. PC A is plugged into switch port 1. It is set to receiving and count multicasts from the switch
I had PC B plugged into switch port 2. PC B is checking switch statistics, but not try to receive multicasts from PC 3.
I had setup multicast snooping on VLAN 1 and querying according to the GUI screen capture below.
Note: I only had a single vlan on this switch.
In a composite of two screen captures below, you can see that IGMP querier status is enabled.
I took off the RV042 out of the network, because i noticed within a wireshark capture on PC A,   that the RV042 was sending out group general queries. I wanted the switch to take over that role
I waited a few minutes, and displayed only igmp activity.
It can be clearly seen in the screen capture below;
SG300 series switch was sending out general queries (2 minutes) from source IP address 172.16.1.100.
It waited for the mcast router general query, but when none came, 60 seconds later sent out it's own general query. Fair enough, it had to assume a mcast router might be sending general queries every minute.
Switch statistics can be seen below, it showed;
that PC B on switch port G2 was not being flooded by multicasts, in other words snooping is working;
Port 10, PC C is sending in 2962 multicast packets to the switch.
Port 1,   PC A is receiving 2900 multicast packets from the switch
port 2 ,   PC B is not part of the multicast group 234.55.66.77 and as such is not being flooded by multicasts.
ALL three PCs are windows based products, and certain multicasts emanate from these devices.
show interafce count
      Port       InUcastPkts InMcastPkts InBcastPkts    InOctets
      gi1             12           9            6           3493
      gi2            247          237           6          43733
      gi3             0            0            0            0
      gi4             0            0            0            0
      gi5             0            0            0            0
      gi6             0            0            0            0
      gi7             0            0            0            0
      gi8             0            0            0            0
      gi9             0            0            0            0
      gi10            26          2962          3          850881
      gi11            0            0            0            0
      gi12            0            0            0            0
      gi13            0            0            0            0
      gi14            0            0            0            0
      gi15            0            0            0            0
      gi16            0            0            0            0
      gi17            0            0            0            0
      gi18            0            0            0            0
      gi19            0            0            0            0
      gi20            0            0            0            0
      gi21            0            0            0            0
      gi22            0            0            0            0
      gi23            0            0            0            0
      gi24            0            0            0            0
      gi25            0            0            0            0
      gi26            0            0            0            0
      gi27            0            0            0            0
      gi28            0            0            0            0
      Port       OutUcastPkts OutMcastPkts OutBcastPkts OutOctets
      gi1             13         2900          9          839691
      gi2            233         343           9          90453
      gi3             0            0            0            0
      gi4             0            0            0            0
      gi5             0            0            0            0
      gi6             0            0            0            0
      gi7             0            0            0            0
      gi8             0            0            0            0
      gi9             0            0            0            0
      gi10            24          343           12         47165
      gi11            0            0            0            0
      gi12            0            0            0            0
      gi13            0            0            0            0
      gi14            0            0            0            0
      gi15            0            0            0            0
      gi16            0            0            0            0
      gi17            0            0            0            0
      gi18            0            0            0            0
      gi19            0            0            0            0
      gi20            0            0            0            0
      gi21            0            0            0            0
      gi22            0            0            0            0
      gi23            0            0            0            0
      gi24            0            0            0            0
      gi25            0            0            0            0
      gi26            0            0            0            0
      gi27            0            0            0            0
      gi28            0            0            0            0
If I look at the multicast groups within the switch, it show that only two ports were involved in multicast group 234.55.66.77. This is the correct behaviour.
switch4cf17c#sh ip igmp snooping group
Vlan   Group        Source        Include Ports        Exclude Ports     Comp.
       Address      Address                                              Mode
1    234.55.66.77 *            gi1,gi10                                  v2
1    239.255.255. *            gi1-2,gi10                                v2
     250
Just to complete the posting, here is the CLI command (highlighted) to enable the querier functionality within the switch;
[Kswitch4cf17c#sh run
bridge multicast filtering
ip igmp snooping
ip igmp snooping vlan 1
ip igmp snooping vlan 1 querier
interface vlan 1
ip address 172.16.1.100 255.255.255.0
exit
interface vlan 1
no ip address dhcp
exit
hostname switch4cf17c
no passwords complexity enable
no snmp-server server
ip telnet server
Hope this helps you and others
regards Dave

IGMP snooping

Hello to all!
I have come a cross one problem with hope someone can help me solve it or at least give some valuable ideas.
The problem is regarding IGMP snooping with Cisco 4948E swithes. By documentation it is said that IGMP snooping is turned on by default.
However, I was getting all multicast traffic on the port where there is only one receiver, tuned to only one multicast group.
I was able to solve to problem by turning igmp snooping querier option and now it is working ok.
However, I have to plug in a Cisco router (7200 series). In that case the router is the querier.
My problem is that the router is constantly getting all multicast traffic, causing the CPU time to increase and be crushed.
I have several multicast groups on the switch, but want only specific ones to be present on the port where router is connected.
I think IGMP snooping is not working on 4948E switches.
Did anybody else experience the same problem?
The router has PIM enabled and I have managed to solve the problem with access list being put in outside direction but this is not the neat solution.
How can I solve this problem? When I do show int command on the router I am getting all multicast traffic and I want to receive only specific ones with way too lower traffic amount.
Thank you very much!

Hello to all!
I have come a cross one problem with hope someone can help me solve it or at least give some valuable ideas.
The problem is regarding IGMP snooping with Cisco 4948E swithes. By documentation it is said that IGMP snooping is turned on by default.
However, I was getting all multicast traffic on the port where there is only one receiver, tuned to only one multicast group.
I was able to solve to problem by turning igmp snooping querier option and now it is working ok.
However, I have to plug in a Cisco router (7200 series). In that case the router is the querier.
My problem is that the router is constantly getting all multicast traffic, causing the CPU time to increase and be crushed.
I have several multicast groups on the switch, but want only specific ones to be present on the port where router is connected.
I think IGMP snooping is not working on 4948E switches.
Did anybody else experience the same problem?
The router has PIM enabled and I have managed to solve the problem with access list being put in outside direction but this is not the neat solution.
How can I solve this problem? When I do show int command on the router I am getting all multicast traffic and I want to receive only specific ones with way too lower traffic amount.
Thank you very much!

Catalyst 2955T-12 Power Supply n IGMP Snooping

Hello everyone,
I have Two Catalyst 2955T-12 switches, on this switch there are Two Power Supply (DC) options...I want to implement redundant Power Supply solution, can this Two DC Input on Switch will give this solution or I have also external Din Rail power supply...my question is how I can implement redundant power supply so that if one PS of switch fails then automatically other will start?
Also can any body tell me what IGMP snooping do? do I need to configure it? also the command (I need global command as well as port/interface based command)?
Regards,
Shahid

For the power redundancy question, I believe this link will help:
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat2950/12122ea2/2955hig/hginstal.htm
Also can any body tell me what IGMP snooping do? do I need to configure it? also the command (I need global command as well as port/interface based command)?
>>Layer 2 switches can use IGMP snooping to constrain the flooding of multicast traffic by dynamically configuring Layer 2 interfaces so that multicast traffic is forwarded to only those interfaces associated with IP multicast devices. As the name implies, IGMP snooping requires the LAN switch to snoop on the IGMP transmissions between the host and the router and to keep track of multicast groups and member ports. When the switch receives an IGMP report from a host for a particular multicast group, the switch adds the host port number to the forwarding table entry; when it receives an IGMP Leave Group message from a host, it removes the host port from the table entry. It also periodically deletes entries if it does not receive IGMP membership reports from the multicast clients.
The multicast router sends out periodic IGMP general queries to all VLANs. When IGMP snooping is enabled, the switch responds to the router queries with only one join request per MAC multicast group, and the switch creates one entry per VLAN in the Layer 2 forwarding table for each MAC group from which it receives an IGMP join request. All hosts interested in this multicast traffic send join requests and are added to the forwarding table entry.
IGMP Snooping is by default Enabled globally and per VLAN. If for some reason it is not enabled, "ip igmp snooping" at the config mode to enable it.
There is nothing else to configure.
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat2950/12122ea5/2950scg/swigmp.htm#wp1020034
Please rate helpful posts.

Multicast trafficis being flooded on igmp snooping enabled switch

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