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Cisco 88xVA – Part 5: VDSL advanced configuration – IPTV v

VDSL IPTV multicast PIM

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#1 Sunfish

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Posted 14 November 2011 - 12:33 AM

This thread belongs to my "Cisco 88xVA – A home router on steroids" project. The initial thread serving as an anchor can be found HERE. Please use that thread for all general comments or requests.


Cisco 88xVA – Part 5: VDSL advanced configuration – IPTV via multicast

Now it's time to add IPTV to the recipe. As previously mentioned some portion of this config might be specific to my ISP but the general concept should be similar in other parts of the world.

We do not have to care about QoS on the outside as our provider is taking care of this by using a dedicated vlan for IPTV multicast traffic. There is also not much we have to do on our side, at least if we connect the receiver directly to one of the switch ports of our router. Things would change a bit if we add other routers/switches between our router and the media receiver but for now they are directly connected.

!
! *** First of all, we need to turn on multicast routing as such on this device
!
ip multicast-routing
!
! *** The next task is to find the ip address of the upstream ISP multicast router
! *** and define it as the rendevous point
! *** Check the "comments and remarks" section for details how to do it
!
ip pim rp-address 172.31.127.254
!
! *** Again, the above mentioned ip is just a placeholder used in this sample config
!
! *** We need to extend our router-on-a-stick config and add a new sub-interface
! *** for the IPTV traffic which is tagged with VLAN 8 in case of my ISP
!
interface Ethernet0.8
description VDSL IPTV-Subinterface - VLAN 8
encapsulation dot1Q 8
ip dhcp client broadcast-flag clear
!
! *** Please note that we do get another public ip address via DHCP
! *** that is dedicated to the multicast stream
!
ip address dhcp
ip mtu 1400
!
! *** Strongly recommended to use sparse-mode as we do have a PIM RP
!
ip pim sparse-mode
no ip route-cache
!
! *** IGMP version and timers might need to be adjusted depending on your ISP
!
ip igmp version 3
ip igmp query-interval 15
ip igmp proxy-service
!
! *** Then we need to configure multicast on our internal interface using sparse-mode as well
!
interface Vlan1
ip pim sparse-mode
!
! *** We need to configure our PIM RP as a helper-address on this inside interface
! *** This is very similar to the function in of a DHCP relay-agent
!
ip igmp helper-address 172.31.127.254
ip igmp version 3
ip igmp explicit-tracking
ip igmp query-interval 15
ip igmp proxy-service
!
! *** Finally, we configure multicast on our dialer interface as well
!
interface Dialer0
ip pim sparse-mode
ip igmp version 3
ip igmp query-interval 15
ip igmp proxy-service
!
! *** Not directly related to our multicast configuration but simply best practice
! *** Remember that the FastEthernet ports on this platform are switch ports!
! *** We use the default VLAN 1 but want to set portfast
!
interface FastEthernet3
description Connection to the IPTV media receiver
spanning-tree portfast
!
end


Comments and remarks

The multicast configuration is pretty straight forward and the only problem might be to find the ip address of the upstream ISP multicast router. At least my ISP does not give you this information as they want you to rent or buy one of their preconfigured routers. So they do not offer any support at all if you use your own router.

There are 2 possible ways to find the pim rp-address. You can either configure an acl that denies all incoming traffic and check the logs for denied multicast packets. The source address of these denied igmp packets is the one we are looking for.

The second way is to temporarily configure pim dense-mode on the interfaces. Pretty obvious that you should change it to dense-mode as soon as you found the correct ip address.

My ISP sends the IPTV stream via unicast for a few seconds until the multicast stream starts. So if multicast is not working, then the picture freezes after a few seconds each time you change the channel. Depending on your acl configuration you might also have to explicitly allow multicast traffic but that will be covered in a separate part.

...and finally don't forget that the newer ISR G2 8xx series routers require an Advanced IP Services license for multicast routing.


What we achieved so far...

We configured our router for IPTV via multicast streaming. The basic feature set that most people expect from a home router is now almost complete, so that it's time to harden our router and improve the security of our network.

In the next part we will have a closer look at ip inspection and access-lists...


Feel free to ask if something is not clear to you!

Comments and questions regarding this part of the configuration should be posted right here while general comments or requests should go into the anchor post mentioned at the beginning.

Edited by Sunfish, 14 November 2011 - 12:35 AM.

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