Optimized Multicast Forwarding (OMF)

On the Nexus 7000 you need to disable OMF for each VLAN with IPv6 traffic. Otherwise IPv6 Neighbor Solicitations and all other IPv4/IPv6 source-only groups are not flooded within the VLAN.
Q1: In my eyes the better workaround is to enable MLD snooping for IPv6 traffic and leave OMF enabled. Is this correct? I didn't have the equipment yet to test.
Q2: On the Nexus 5000 OMF is also enabled by default but IPv6 traffic works (including Neighbor Discovery) even when OMF is still enabled and MLD Snooping is turned off. Do you know why?
Tested with 5548UP/5.2(1) and 5596UP/6.0(2) code.
Q3: It seems that the Sup2T on the catalyst 6500/6800 also implements OMF by default. Does anyone know if IPv6 traffic is forwarded by Sup2T without turning off OMF and without turning on MLD snooping?
Robert

I believe the problem has less to do with the PIM mode specified and more to do with the address chosen. I quote this from the IANA documentation on assignment of multicast addresses:
The range of addresses between 224.0.0.0 and 224.0.0.255, inclusive,
is reserved for the use of routing protocols and other low-level
topology discovery or maintenance protocols, such as gateway discovery
and group membership reporting. Multicast routers should not forward
any multicast datagram with destination addresses in this range,
regardless of its TTL.
What is generating this multicast traffic and how did it choose this particular multicast address?
I believe that if you change the address to something outside of the reserved range that it will work much better.
HTH
Rick

Similar Messages

  • Which Linksys VPN Routers support Multicast forwarding

    Which Linksys VPN Routers support Multicast forwarding / passthru   I have remote SPA942 phones connected thru a vpn to a SPA9000/SPA400 system. After manual provisioning the phones work, but voice mail, auto provisioning, etc that use multicast do not work. VPN is using Netgear boxes which do not forward multicast. I'm going to switch to Linksys/Cisco VPN routers but want to make sure which models will do the multicast forwarding.
    Thanks   

    I only no of 1 for sure and that is by downloading 3rd party firmware like DD-WRT, the WRT54G. See the below Link.
    http://en.wikipedia.org/wiki/Wireless_Distribution_System
    Ttech

  • Multicast forwarding

    Hi,
    Cat3750 needs to forward multicast between vlans. Multicast address is 224.0.0.251.
    I've tried several methods, but it did no succeed. The switch log debug says one of the following :
    IP: s=192.168.2.4 (Vlan2), d=224.0.0.251, len 72, stop process pak for forus packet
    or
    IP: s=192.168.2.4 (Vlan2), d=224.0.0.251, len 72, unroutable
    Multicast routing is enabled. I've tried igmp helper and ip multicast helper as well.
    Is it possible to forward this Multicast address ?
    Regards,
    L.

    I believe the problem has less to do with the PIM mode specified and more to do with the address chosen. I quote this from the IANA documentation on assignment of multicast addresses:
    The range of addresses between 224.0.0.0 and 224.0.0.255, inclusive,
    is reserved for the use of routing protocols and other low-level
    topology discovery or maintenance protocols, such as gateway discovery
    and group membership reporting. Multicast routers should not forward
    any multicast datagram with destination addresses in this range,
    regardless of its TTL.
    What is generating this multicast traffic and how did it choose this particular multicast address?
    I believe that if you change the address to something outside of the reserved range that it will work much better.
    HTH
    Rick

  • Using a 3rd party router for Multicast

    Hi all,
    There’s a lot of feedback on this board about using third party routers with Multicast, so we’ve decided to put this information all in the one place for you.
    NOTE: the workarounds below haven’t been tested by BT as we do not support 3rd party routers and we do not endorse any of them. Our recommended router remains the Home Hub.
    With the above statement in mind, we know that a lot of you do choose to use other routers.  The information contained here has come from fellow customers who have given their time to share this information in good faith. Thanks to all of the forum members who have helped make this information available to our community it is a great example of the wealth of information that a community can provide and we hope this encourages users to come back and visit us in the future.
    A special mention goes to walkerx who has posted and prompted a lot of the provided information.
    Hub configurations in alphabetical order:
    Apple Airport Extreme
    Put your Airport Extreme into Bridge Mode and turn the Home Hub's wireless off.
    [From MartinH's post]
    ASUS RT-N66U
    You must configure 'Enable VPN + DHCP Connection' to 'No' under the WAN option.
    Settings used were:
    - Have router on the latest firmware: 3.0.0.4.374.130
    - Use the following settings in LAN > IPTV:
    - 'Select ISP Profile' = None
    - 'Choose IPTV STB Port' = None
    - 'Use DHCP routes' = Microsoft
    - 'Enable multicast routing (IGMP Proxy) = Enable
    - 'Enable efficient multicast forwarding (IGMP Snooping) = Enable
    - 'UDB Proxy (Udpxy) = 0
    [From sepph's post]
    Billion 7800DXL
    Router has been reported to work.
    [From walkerx's post]
    Billion 7800N
    Requires you to add another profile (Pure Bridge) to the EWAN port along with the PPPoE profile. Save settings & restart. Also enable IGMP proxy & snooping.
    [TimCurtis' post]
    DLink Dir 825
    If enable multicast you can see the on-demand players but get an IPC6023 error when viewing the test channel (this means poor internet channel quality). This error message comes up even though it works if use the Home Hub 4
    [walkerx's post]
    Netgear R6300
    Netgear R6300, but with the Home Hub 3.0 and 500Mbit Powerline adapters in the picture.
    Modem -> HH3 -> R6300 -> Powerline -> 2 x Youview Boxes on other Powerlines.
    To do this, configure the Home Hub 3.0 as 192.168.1.1, then disable its wireless and DHCP. Make sure that NAT and UPNP were enabled, and then set it to use the address 192.168.1.254 as a DMZ server.
    Then configure the R6300 as the address 192.168.0.1, using the WAN IP address of 192.168.1.254, with 192.168.1.1 as the gateway and DNS server. The R6300 is then connected via WAN port to the HH3 Gigabit port.
    In the R6300 settings switch on IGMP. 
    The above settings allow both YouView boxes to use on demand content and different streaming channels simultaneously, as well as giving the full features of the R6300 such as AC1750 wireless, network printing, and DLNA
    [wigglr's post]
    TP-Link AC1750
    Router has been reported to work.
    [zarf2007's post]
    TP-Link Archer C7
    Router has been reported to work.
    [HappySlayerUK's post]
    TP-Link TL-WR1043ND
    No configuration needed, plug and play.
    [walkerx's post]
    TP-Link WDR4300 N750
    Router has been reported to work.
    [aseymour's post]
    TP-Link TL-WDR4900 N900
    Router has been reported to work, plug and play.
    [cactusbob's post]
    TP-Link routers in general
    How to configure Multicast on TP-Link routers (from the TP-Link website).
    One of our posters also found the following:
    He found that your router must be able to do the following for Multicast:
    For an end user connected via Openreach GEA (FTTC and FTTH)
    • The Residential Gateway will support:
    – IPoE for multicast traffic and PPPoE for BB traffic;
    – VLAN tag ID of 0 or no VLAN tag ID for multicast and BB traffic;
    – Fork IGMP requests up multicast and BB paths.
    For an end user connected to an MSAN (WBC copper)
    • The Residential Gateway will support:
    – A dual VC architecture;
    – Accept TV Connect multicast traffic on ATM VP/VC 0/35 with IPoE and broadband traffic on ATM VP/VC 0/38 with PPPoE;
    – Fork IGMP requests up multicast and broadband paths.
    IGMP should v3 and will be in range from 225.0.0.0 to 239.255.255.255 
    [walkerx's post]
    List of routers that do not appear to work:
    Draytek 2750n
    Linksys EA4500
    linksys EA6300
    Netgear AC6300
    [From Red_Snow's post]
    If you use a router that’s not listed here, do a search on the YouView from BT board to see if advice has been posted elsewhere. If it hasn’t, do post your question.
    Thanks,
    Stephanie
    Stephanie
    BTCare Community Manager
    If you like a post, or want to say thanks for a helpful answer, please click on the Ratings star on the left-hand side of the post. If someone answers your question correctly please let other members know by clicking on ’Mark as Accepted Solution’.

    Thanks for confirming that quails.
    Cheers
    David
    BTCare Community Mod
    If we have asked you to email us with your details, please make sure you are logged in to the forum, otherwise you will not be able to see our ‘Contact Us’ link within our profiles.
    We are sorry but we are unable to deal with service/account queries via the private message(PM) function so please don't PM your account info, we need to deal with this via our email account :-)

  • WLC - AP Groups - Multicast - Bonjour - Apple TVv3

    Good Morning
    first off - Should start off by saying I have followed the Apple Bonjour deployment guide [except for interface group] portion
    I have searched high and low, here and there to no avail.
    http://www.cisco.com/en/US/products/hw/wireless/ps4570/products_tech_note09186a0080bb1d7c.shtml
    I am aware that the bonjour gateway IOS may or may not come out in Oct/Nov 2012, which maybe my only option at this point.
    Is this not working because of my AP groups setup or have I misssed something
    I can only get bonjour to work if multicast - unicast mode is selected, but our network slowly grinds to a halt, so it is not an option
    when I first connect to the wireless I see 1 bonjour device for about 3 minutes and then disappears.
    I can not see the appletv at all with an ipad, airplay does not appear at all.
    We have the following setup.
    2 campuses - Campus 2 is simular setup, but WLCs higher model and ios 7.2 and clients and subnets are double
    Campus 1
    2 WLC 4404 ios 7.0.230.0
    30 AP groups mapped to 30 Interfaces using subnets with /23 bit subnetmasks
    multicast - multicast is set with multicast addresses of
    controller 1 239.239.5.1 and
    controller 2 239.239.5.2
    multicast is enabled
    IGMPsnooping as well
    On Switch multicast routing is enabled
    all AP group subnets and Mgmt vlans are PIM enabled dense mode
    set up a trunk to ubuntu server to act as a bonjour gateway, installed avahi and vlan
    mapped all AP and mgmt vlans to Ubuntu server.
    avahi see the following + more
    + eth0.136 IPv6 Apple TV                                      _airplay._tcp        local
    + eth0.136 IPv4 Apple TV                                      _airplay._tcp        local
    + eth0.134 IPv6 Apple TV                                      _airplay._tcp        local
    + eth0.134 IPv4 Apple TV                                      _airplay._tcp        local
    + eth0.132 IPv6 Apple TV                                      _airplay._tcp        local
    + eth0.132 IPv4 Apple TV                                      _airplay._tcp        local
    + eth0.130 IPv6 Apple TV                                      _airplay._tcp        local
    more goes on forever
    + eth0.136 IPv4 xyz Library                             Apple Home Sharing   local
    show ip multicast
      Multicast Routing: enabled
      Multicast Multipath: disabled
      Multicast Route limit: No limit
      Multicast Triggered RPF check: enabled
      Multicast Fallback group mode: Dense
    show ip multicast interface vlan 128
    Vlan128 is up, line protocol is up
      Internet address is x.x.128.1/23
      Multicast routing: enabled
      Multicast switching: fast
      Multicast packets in/out: 14671352/276693
      Multicast boundary: not set
      Multicast TTL threshold: 0
      Multicast Tagswitching: disabled
    Where do I go from here?

    Thanks Yahya and Stephen
    I have tried to simplify my config as much as possible.
    wlc 4404
    Ethernet Multicast Forwarding............... Enable
    Ethernet Broadcast Forwarding............... Enable
    AP Multicast/Broadcast Mode................. Multicast   Address : 239.239.5.1
    IGMP snooping............................... Enabled
    IGMP timeout................................ 60 seconds
    IGMP Query Interval......................... 20 seconds
    I have an interface created 10.x.x.x/23
    I have created a new SSID APPLETV - assigned Interface
    I have added the SSID to just 1 AP Group
    show network multicast mgid summary
    Layer2 MGID Mapping:
    InterfaceName                    vlanId   MGID
    2upadhoc                         136      27
    Layer3 MGID Mapping:
    Number of Layer3 MGIDs........................... 11
    My vlan does not show up here.
    I only have 2 devices in this vlan the AppleTV and IPAD
    checking the switch for all required vlans
    show ip multicast
      Multicast Routing: enabled
      Multicast Multipath: disabled
      Multicast Route limit: No limit
      Multicast Triggered RPF check: enabled
      Multicast Fallback group mode: Dense
    admin interface
    Management, AP-Manger
    Vlan12 is up, line protocol is up
      Internet address is x.x.x.1/24
      Multicast routing: enabled
      Multicast switching: fast
      Multicast packets in/out: 238489978/724352
      Multicast boundary: not set
      Multicast TTL threshold: 0
      Multicast Tagswitching: disabled
    AP vlan
    Vlan222 is up, line protocol is up
      Internet address is x.y.z.1/24
      Multicast routing: enabled
      Multicast switching: fast
      Multicast packets in/out: 11423/238338583
      Multicast boundary: not set
      Multicast TTL threshold: 0
      Multicast Tagswitching: disabled
    The test Apple TV Vlan
    Vlan136 is up, line protocol is up
      Internet address is x.xx.1/23
      Multicast routing: enabled
      Multicast switching: fast
      Multicast packets in/out: 156740/0
      Multicast boundary: not set
      Multicast TTL threshold: 0
      Multicast Tagswitching: disabled
    interface Vlan12
    ip pim dense-mode
    interface Vlan222
    ip pim dense-mode
    interface Vlan136
    ip pim dense-mode
    Show ip igmp groups
    Group Address    Interface                Uptime    Expires   Last Reporter
    224.0.1.39       Vlan136                  2d00h     00:02:35  x.x.x.1
    So just to recap
    Same subnet in a AP Group
    New SSID
    multicast enabled on WLC - using multicast multicast mode
    Broadcast forward enable
    Switch -Multicast routing enabled
    all vlans enabled for PIM
    2 devices - added Imac to see if I could home share through Itunes.
    end result
    no bonjour clients, no apple tv, no airplay
    Bonjour Gateway device - although same subnet it shouldn't be needed
    eth0.12   Link encap:Ethernet  HWaddr bc:30:5b:x:x:x 
              inet addr:x.x.x.244  Bcast:x.x.x.255  Mask:255.255.255.0
              inet6 addr: fe80::be30:5bff:fed6:a178/64 Scope:Link
              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
              RX packets:55005 errors:0 dropped:115 overruns:0 frame:0
              TX packets:23003 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:0
              RX bytes:2776156 (2.7 MB)  TX bytes:11285256 (11.2 MB)
    eth0.136  Link encap:Ethernet  HWaddr bc:30:5b:x:x:x 
              inet addr:x.x.x.9  Bcast:x.x.x.255  Mask:255.255.254.0
              inet6 addr: fe80::be30:5bff:fed6:a178/64 Scope:Link
              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
              RX packets:42167 errors:0 dropped:115 overruns:0 frame:0
              TX packets:22340 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:0
              RX bytes:3251242 (3.2 MB)  TX bytes:10373581 (10.3 MB)
    eth0.222  Link encap:Ethernet  HWaddr bc:30:5b:xx:xx:xx 
              inet addr:x.x.x.9  Bcast:x.x.x.255  Mask:255.255.255.0
              inet6 addr: fe80::be30:5bff:fed6:a178/64 Scope:Link
              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
              RX packets:152397 errors:0 dropped:115 overruns:0 frame:0
              TX packets:23768 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:0
              RX bytes:12795709 (12.7 MB)  TX bytes:11318103 (11.3 MB)
    + eth0.222 IPv6 67665ACD317A45B0                              _appletv-v2._tcp     local
    + eth0.222 IPv4 67665ACD317A45B0                              _appletv-v2._tcp     local
    + eth0.136 IPv6 67665ACD317A45B0                              _appletv-v2._tcp     local
    + eth0.136 IPv4 67665ACD317A45B0                              _appletv-v2._tcp     local
    + eth0.12 IPv6 67665ACD317A45B0                              _appletv-v2._tcp     local
    + eth0.12 IPv4 67665ACD317A45B0                              _appletv-v2._tcp     local
    Should Bonjour work same subnet with these settings?
    I am going to have read more about the Interface groups and the Multicast vlan.

  • Does Aironet AP1121G support multicast?

    Hello everybody.Can the two wireless client under the same AP1121G support the multicast forwarding?What do I config on the AP1121G?
    Thanks a lots.

    Hi,
    What is the IOS version of your AP?
    Refer to the following url on how to configure filter to allow multicast forwarding.
    http://www.cisco.com/en/US/products/hw/wireless/ps4570/products_configuration_guide_chapter09186a0080341cc4.html
    *Look under 'Configuring and Enabling IP Filters'
    Hope it helps.
    Rgds,
    AK

  • Multicast blocking in layer 2 switch

    Hello there,
    I need your help, this is the problem that I have.
    We have a 3750X with 7 ports assigned to a different multicast IP address (connected to the encoders), these are the ports with the multicast ip address and the rate that the encoder is sending:
    Pto 2 - 230.1.1.1:5001 - 3.5 Mbps
    Pto 3 - 230.1.1.2:5002 - 3.5 Mbps
    Pto 13 - 230.1.1.22:5022 - 15 Mbps
    Pto 13 - 230.1.1.23:5023 - 15 Mbps
    Pto 13 - 230.1.1.24:5004 - 15 Mbps
    Pto 13 - 230.1.1.25:5025 - 15 Mbps
    Pto 13 - 230.1.1.26:5026 - 5.0 Mbps
    The last port (48) is connected to a different device and this box is receiving the multicast ip addresses. My problem is that in every single port on the switch is receiving all the multicast traffic so the switch is having high cpu, I have the outputs from the console monitor (application that sees the odd behavior).
    As far as I know this is expected since this is layer 2 device but I'm not sure. Please help so I can configure what I need to stop the high cpu and the traffic to be sent over the rest of the ports (including those ports).
    Kindly regards

    Hi ,
    You can block layer 2 Multicast traffic with following commands
    Step 3 
    switchport block multicast
    Block unknown multicast forwarding out of the port.
    Note Only pure Layer 2 multicast traffic is blocked. Multicast packets that contain IPv4 or IPv6 information in the header are not blocked.
    http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2960/software/release/12-2_55_se/configuration/guide/scg_2960/swtrafc.html
    HTH
    Sandy

  • Multicast questions

    Good Morning.
    We were looking to deploy wireless VoIP phones into our environment. These phones have a PTT feature which utilizes Multicast.
    I was looking into configuring Multicast mode on the wireless controller and access points in our network. Do you think this is necessary or at least recommended for the PTT application or do I just let the unicast mode continue to function.
    Also if we do enable multi-cast mode and videostream it is not supported on the Flex AP's. Would the Flex AP's still join the controllers or would we have to move the Flex AP's to another controller?

    Saravanan Lakshmanan wrote:Does the Flex AP's default to Multicast-Unicast even if Multicast-Multicast is set on the global controller config?//No, it doesn't receive Multicast packets from WLC.Let see what're the parameters that can affect Multicast forwarding:#WLC platform.#Global AP Multicast mode config at WLC.#Mode of the AP - Local, Flexconnect central switching.#With flex Local switching, it doesn't even send/receive the packet to/from WLC, so it doesn't matter what Multicast mode is configured on wlc. Multicast support on different WLC platforms:#WLC 5500/WiSM2/8500 supports both Multicast and Unicast mode.#WLC 2500 supports Multicast to Multicast only.#WLC 7500 & vWLC supports Multicast to Unicast only. Supports Flex APs only. #Flexconnect mode AP can't join Multicast group address configured at WLC -> AP mode Multicast to Multicast. Since it is not joined to the Multicast group, it can't receive Multicast packet that are sent by WLC(and Multicast packet sent by flex central switching will be received by local mode APs only). If Multicast needs to be forwarded for flexconnect central switching then configure AP mode Multicast to Unicast. Remember, it is global config that's applicable for local mode AP also. #WLC 5500/WiSM2/8500 supports both Multicast and Unicast mode.//When mix of local mode AP and flex central switching is used where flex centrally switched wlan need to forward/receive Multicast traffic then need to set "AP Multicast mode to Unicast only". (With Multicast mode enabled, WLC can't send one copy to the Multicast address and individual copies to the Flex mode APs.) #WLC 2500 supports Multicast to Multicast only.//Flex central switched APs can't receive Multicast packets since it doesn't support Unicast mode. Use Flex local switching as workaround in this case. #WLC 7500 & vWLC supports Multicast to Unicast only. Supports Flex APs only.//It supports only Flex APs, so Multicast to Unicast is the only applicable config that is allowed. Since it is not cco documented, will try to address this on Multicast section of config guide.
    So I read this again. Say we have Flex Central switching then we MUST configure AP unicast if the clients on the Flex AP need to be able to stream multicast? So if that is the case then the client just wont be able to join the multicast group?

  • Blocking Multicast on Layer 2 switch

    Cisco 2960, layer 2.
    trying to block inbound multicast from a single switchport.  My CUCM to be exact.
    IGMP will not do what I need as I have phones trying to listen to Multicast MOH from the server, and Im trying to block it.  Phones and server are on the same subnet.  I do not want the MC packets to hit the phones as they need to listen to something else on the same IP
    ACL on the port didnt work, neither did switch block multi as I think it doesn't block packets with a correct source mac.
    Storm-control multi level 0 didnt work, neither does storm-control broad level 0
    Any other options?  Or are one of these options actually working and I just dont know it (my multicast isn't setup right lets say).  I see my multicast counters on the port go up when I turn on multicast from the server so I know its being sent.

    Hi ,
    You can block layer 2 Multicast traffic with following commands
    Step 3 
    switchport block multicast
    Block unknown multicast forwarding out of the port.
    Note Only pure Layer 2 multicast traffic is blocked. Multicast packets that contain IPv4 or IPv6 information in the header are not blocked.
    http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2960/software/release/12-2_55_se/configuration/guide/scg_2960/swtrafc.html
    HTH
    Sandy

  • Multicasting with an SGE2010P

    Hi,
    I have just purchased a SGE2010p switch. I am hoping to multicast with windows deployment services WDS
    and also hoping someone might be able to give a basic explanation (configuration would be brilliant!) on the process.
    On the switch webpage, we ticked the box for IGMP snooping. WDS configured with multicasting and that part of
    it works. Getting transfer rates of 16,000KBps (according to WDS console). Would have thought gigabyte should be
    better than that, but still better than the 250KBps without IGMP snooping.
    The problem is that all traffic is still being sent to all other ports on the switch. There is only the switch
    and no routers involved. Some documents indicate IGMP querier is required, but there seems no option for that that
    I can find. I believe we later enabled autolearn (but not certain - dont have access to the switch at the moment)
    and then WDS broke <again>.
    So I am hoping someone can please educate me!
    What needs to be done to prevent the switch from forwarding data to all ports
    Is AutoLearn the same as an IGMP querier?
    What is bridge multicast forwarding? Sounds like passing multicasts across routers?.
    Do we need to create a multicast group on the switch? I would think no, that WDS does all that.
    Does this switch support MLD snooping?
    Any help appreciated
    thank you!

    That's not going to work; manually defining groups means static multicasting (ie not dynamic nor scalable). That sort of defeats the purpose of IGMP snooping.
    The problem is Microsoft's default multicast range is incompatible with IGMP and switches.
    When a multicast layer 3 address is mapped to layer 2 (for the switch multicast layer 2 address), only the last 23 bits of the IPv4 address come across. The other bits are lost as we need specify the ethernet OUID owned by iana.  (01-00-5e).
    So the default range by microsoft 239.0.0.1-239.0.0.255 maps out at the ethernet layer:  01-00-5e-00-00-01 to 01-00-5e-00-00-ff
    The problem is, the 224.x.x.x mulicast control messages also map out like that, e.g. 224.0.0.1 maps to 01-00-5e-00-00-01.
    So 224.0.0.1 and 239.0.0.1 map to the same ethernet (layer 2) mac address. Therefore the switch has no alternative but to broadcast as 224.0.0.1 = all nodes.
    So try changing the default WDS address to something that wont get confused by the switch, e.g. 239.67.54.3 to 239.67.54.255.
    Have tested this in a lab only but should fix the problem.
    bye
    Oh, bridge multicast forwarding is for when the traffic needs to be forwarded (ie to another switch or router). Filtering is only to be touched to block all multicast traffic - perhaps for permanent groups that need to be manually configured. You dont need to touch that.

  • 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. 

  • WLC(s): are "forwarding" broadcast pkts when I don't want them to.

    The symptom is whenever a wireless clients generates a broadcast packet the WLCs pick it up and send it(capwap encapsulated) to each and every AP(Unicast) in every building.  Such that a single client broadcast packet causes our WLCs to generate 1000 separate packets. 
    We have multiple buildings(20) connected by VPN's over cable modems. Each building has ~25+ APs all set to Flex-Connect and local switching. Back here at central we have several 5508 WLCs.
    We have broadcast forwarding disabled.
    Show Network Summary 
    Ethernet Multicast Forwarding............... Enable
    Ethernet Broadcast Forwarding............... Disable
    IPv4 AP Multicast/Broadcast Mode............ Unicast
    IPv6 AP Multicast/Broadcast Mode............ Unicast
    IGMP snooping............................... Enabled
    I'm calling these CAPWAP encapsulated packets "broadcasting forwarding" but I not sure that is the correct way to describe them.  Either way I'd like to understand what the packet are and can we make them stop.  
    The TOD(Theory Of the Day w/all due respect to Stephen H.) is that these unicasts to the APs are somehow related to Layer 3 mobility....

    What is the WLC software version in this case ?
    Refer this link & that explain WLC default behavior for wireless client's broadcast packets. It should not broadcast to other wireless clients/AP.
    http://www.cisco.com/c/en/us/td/docs/solutions/Enterprise/Mobility/emob73dg/emob73/ch2_Arch.html#pgfId-1058225
    In your case, if you can take a wireshark capture of the AP connected switchport you can verify client broadcast is forwarding as it is or not. It is good if you can take OTA capture as well so you can confirm client sending broadcast traffic.
    HTH
    Rasika
    **** Pls rate all useful responses ****

  • MultiCasting with applets ??

    Hi
    I would like to ask about how can i avoid the problem of using the multicast socket with the applet as i want to build an applet and i knew that multicasting is not applicable with applets
    but also i wanna use multicast socket for the multicasting of data stream in conferencing project
    so any suggestions related to this problem is appreciated
    thanks alot in advance

    That's not going to work; manually defining groups means static multicasting (ie not dynamic nor scalable). That sort of defeats the purpose of IGMP snooping.
    The problem is Microsoft's default multicast range is incompatible with IGMP and switches.
    When a multicast layer 3 address is mapped to layer 2 (for the switch multicast layer 2 address), only the last 23 bits of the IPv4 address come across. The other bits are lost as we need specify the ethernet OUID owned by iana.  (01-00-5e).
    So the default range by microsoft 239.0.0.1-239.0.0.255 maps out at the ethernet layer:  01-00-5e-00-00-01 to 01-00-5e-00-00-ff
    The problem is, the 224.x.x.x mulicast control messages also map out like that, e.g. 224.0.0.1 maps to 01-00-5e-00-00-01.
    So 224.0.0.1 and 239.0.0.1 map to the same ethernet (layer 2) mac address. Therefore the switch has no alternative but to broadcast as 224.0.0.1 = all nodes.
    So try changing the default WDS address to something that wont get confused by the switch, e.g. 239.67.54.3 to 239.67.54.255.
    Have tested this in a lab only but should fix the problem.
    bye
    Oh, bridge multicast forwarding is for when the traffic needs to be forwarded (ie to another switch or router). Filtering is only to be touched to block all multicast traffic - perhaps for permanent groups that need to be manually configured. You dont need to touch that.

  • Multicast Spillover

    I am a newbie to network switch configuration and my group recently bought an SG 300-28 Gigabit Managed Switch.
    It appears by default to spill over (forward) all multicast traffic to all ports.
    I want to reconfigure it to only forward multicast traffic to the ports that have joined that specific multicast.
    I currently have one connection to our business LAN (10.45.x.x) for configuration on g24.
    I have a PC (192.168.1.153) connected to g1 that is streaming out 2 multicast feeds (239.255.5.5:5005 and 239.255.6.6:5006)
    I have another PC (192.168.1.159) connected to g13 that can receive 1, 2 or niether multicast feed(s). 
    I see that there is a multicast menu in the user GUI, but I'm not sure what items I should be modifying.
    Any help would be appreciated.
    Doug   

    Thanks Thomas,
    Perhaps I should clarify that the multicast traffic is successfully getting to the destination PC.  That is not the problem.
    What I am trying to do is:
    1.  Prevent the multicast traffic from cluttering up our business LAN (the connection on g24)
    2.  Save bandwidth on each connection by only sending multicasts to those ports that request to join the multicast.
    Although my test is using only 2 multicasts, once I have the switch configured I will put it into a system that has dozens (approaching 100) multicast streams on it.  The multicasts will quickly use up all bandwidth on all ports if they are being forwarded to all ports.
    So I read through the Administration guide and:
    1. Under Multicast->Properties I enabled "Bridge Multicast Filtering Status"
    2. Under Multicast->IGMP snooping I enabled "IGMP Snooping Status" and enabled IGMP snooping on all VLANs using IGMP v3.
    3. Under Multicast->Forward All I left all ports in all VLANs set to "None"
    4. Under Multicast->Unregistered Multicast I set g1-g24 to "filtering" and left g25-g28 as "Forwarding"
    In order to test whether it was working as expected, I went to Status and Statistics->Interface, chose g1 (the multicast source), 15 second refresh rate, and Clear all Interface Counters, then I watched how the Multicast counters incremented each 15 seconds.
    I did the same with g13 (the multicast receiver) under various conditions (receiving only 1 multicast, both multicasts, no multicasts, PC turned off, ethernet cable unplugged)
    The Multicast TX counter increments about 14k-15k each 15 seconds when both multicasts are received, about 12k each 15 seconds when one multicast is received or no multicasts are received (like when the PC is turned off but the ethernet cable is still plugged in).  It doesn't increment when the ethernet cable is unplugged from the receiving PC.
    So I'm not sure if these counters are a good metric, but I would expect the TX count to not increment if the PC is turned off (no multicasts are joined), and I would expect the count difference to be greater when 1 versus 2 multicasts are joined.
    Do you have a better way to verify whether the switch is behaving as expected?
    Doug

  • Server to Server Multicast Query

    Dear All,
    I have a below query related to Basic (Server to Server) multicast within the same subnet and vlan but connected to two different switches.
    Below is the scenario:
    In N5K = Acting as a layer 2 and "ip igmp snooping" is enabled
    In Dist_CAT65K= Acting as a layer 2 for Vlan1 and "no ip igmp snooping" configured globally (disabled)
    In Core_CAT65K= Acting as a layer 3 for Vlan1 (SVI) and "no ip igmp snooping" configured globally (disabled)
    Server-1 ---> N5K-1 ---> Dist_CAT65K-1 ---> "Core_CAT65K-1 <<====>> Core_CAT65K-2" <--- Dist_CAT65K-2 <---- N5K-2 <----- Server-2 
    Kindly suggest what is the best way to enable multicast end to end.
    I have one solution to enable 'pim' under SVI in the core switch:
    Core_CAT65K:
    interface Vlan1
    ip address 1.1.1.1 255.255.255.0
    ip pim sparse-dense-mode
    end
    To enable 'pim,' Do we need to enable "ip multicast-rouing" in Core_CAT65K?
    Do we need to enable "ip igmp snooping" in  Core_CAT65K?
    Is it better to enable "ip igmp snooping" in Dist_CAT65K? What If we not enable IGMP Snooping on Dist_CAT65K?
    Or Multicast will still work without doing anything because IGMP is disabled on Core_CAT65K &  Dist_CAT65K and Multicast packets will be treated as Broadcast in Core_CAT65K?
    What is the best way?
    Regards,
    Anser

    Hi Jon,
    Thanks again. Just to clarify, What is the impact If I disable IGMP Snooping globally and enable on the specific SVI & vlan? e.g
    Core_C65K:
    Config# no ip igmp snooping
    Config# no ip igmp snooping querier
    Config# inter vlan 1
    Config-if)#ip igmp snooping
    Config-if)#ip igmp snooping querier
    Dist_C65K:
    Config# no ip igmp snooping
    Config# vlan configuration 1
    Config-vlan# ip igmp snooping
    N5K:
    Enable (ip igmp snooping) globally & Vlan as well.
    Can I get the optimal multicast traffic between the same VLAN with the above configuration?
    Regards,
    Anser

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