Anyone using ASM (versus SSM) for IPTV? If so why? thanks, mike
Dear Mike; On Wed, Dec 28, 2011 at 4:48 PM, Mike McBride <mmcbride7@gmail.com> wrote:
Anyone using ASM (versus SSM) for IPTV? If so why?
From what I understand, the answer is likely to be "yes" and the reason is likely to be "deployed equipment only supports IGMP v2."
Regards Marshall
thanks, mike
Marshall, On Wed, Dec 28, 2011 at 1:50 PM, Marshall Eubanks <marshall.eubanks@gmail.com> wrote:
Dear Mike;
On Wed, Dec 28, 2011 at 4:48 PM, Mike McBride <mmcbride7@gmail.com> wrote:
Anyone using ASM (versus SSM) for IPTV? If so why?
From what I understand, the answer is likely to be "yes" and the reason is likely to be "deployed equipment only supports IGMP v2."
Agreed. I'm seeking confirmation, from IPTV implementers, that non igmpv3 support is the reason for using ASM with IPTV. Versus other reasons such as reducing state. Or is this a non issue and everyone is using SSM with IPTV? thanks, mike
Regards Marshall
thanks, mike
Mike, To my knowledge in most today's networks even if legacy equipment don't support IGMPv3 most likely 1st hop router does static translation and SSM upstream. The reason not to migrate to SSM is usually - ASM is already there and works just fine :) Cost to support RP infrastructure is usually the main non-technical factor to not to use ASM. Would be interested to hear from the SPs on the list. Regards, Jeff On Dec 28, 2011, at 2:19 PM, "Mike McBride" <mmcbride7@gmail.com> wrote:
Marshall,
On Wed, Dec 28, 2011 at 1:50 PM, Marshall Eubanks <marshall.eubanks@gmail.com> wrote:
Dear Mike;
On Wed, Dec 28, 2011 at 4:48 PM, Mike McBride <mmcbride7@gmail.com> wrote:
Anyone using ASM (versus SSM) for IPTV? If so why?
From what I understand, the answer is likely to be "yes" and the reason is likely to be "deployed equipment only supports IGMP v2."
Agreed. I'm seeking confirmation, from IPTV implementers, that non igmpv3 support is the reason for using ASM with IPTV. Versus other reasons such as reducing state. Or is this a non issue and everyone is using SSM with IPTV?
thanks, mike
Regards Marshall
thanks, mike
SSM is also used since we *know* the IP addresses of the content servers that are the sources - You dont need ASM. I dont think maintaining RP infrastructure is trivial. Who wants to deal with register packets, etc. Small routers punt all registers to CPU and them forward them in SW. In fact there was a draft which proposed using MPLS encapsulation in networks that support MPLS to replace the existing RP mechanism. http://tools.ietf.org/html/draft-bhatia-pim-mpls-register-packets-00
From the draft:
Encapsulation and Decapsulation are expensive operations for routers and the latter, especially, as it entails a double lookup that many routers cannot do in hardware. It is for this reason that several off the shelf chips do not support decapsulating the PIM Register packets. Any router that cannot decapsulate the PIM Register packet in hardware must send all this traffic to CPU, where its decapsulated, and forwarded based on the multicast forwarding table. This increases the load on the CPU and also makes the router susceptible for DoS attacks. Also, since Register packets are unicast, then can be easily spoofed and an attacker can use this to attack the router and thus the network. This document attempts to solve the above problems by doing away with the PIM Register packets. It instead proposes using an MPLS tunnel to send all multicast data traffic till an SPT is formed. This eliminates the complexity of decapsulating PIM register packets on the RP as it now only needs to pop off the MPLS labels before forwarding the native packet down the RPT. Looks like the draft died some time back .. Glen On Thu, Dec 29, 2011 at 5:02 AM, Jeff Tantsura <jeff.tantsura@ericsson.com> wrote:
Mike,
To my knowledge in most today's networks even if legacy equipment don't support IGMPv3 most likely 1st hop router does static translation and SSM upstream. The reason not to migrate to SSM is usually - ASM is already there and works just fine :) Cost to support RP infrastructure is usually the main non-technical factor to not to use ASM. Would be interested to hear from the SPs on the list.
Regards, Jeff
On Dec 28, 2011, at 2:19 PM, "Mike McBride" <mmcbride7@gmail.com> wrote:
Marshall,
On Wed, Dec 28, 2011 at 1:50 PM, Marshall Eubanks <marshall.eubanks@gmail.com> wrote:
Dear Mike;
On Wed, Dec 28, 2011 at 4:48 PM, Mike McBride <mmcbride7@gmail.com> wrote:
Anyone using ASM (versus SSM) for IPTV? If so why?
From what I understand, the answer is likely to be "yes" and the reason is likely to be "deployed equipment only supports IGMP v2."
Agreed. I'm seeking confirmation, from IPTV implementers, that non igmpv3 support is the reason for using ASM with IPTV. Versus other reasons such as reducing state. Or is this a non issue and everyone is using SSM with IPTV?
thanks, mike
Regards Marshall
thanks, mike
On Thursday, December 29, 2011 07:58:53 AM Glen Kent wrote:
SSM is also used since we *know* the IP addresses of the content servers that are the sources - You dont need ASM. I dont think maintaining RP infrastructure is trivial. Who wants to deal with register packets, etc. Small routers punt all registers to CPU and them forward them in SW.
Our Sender PE routers double as our RP's. These are Juniper M320's and T320's today. Yes, a Tunnel PIC is required on the Juniper's (although you might find it interesting that if you're running PIM-SM for IPv6 on Sender PE routers, you don't need a Tunnel PIC; however, if you have an IPv6-based RP, you need a Tunnel PIC). Juniper MX routers don't require a Tunnel PIC, as those are integrated into their DPC and MPC line cards. Our customer is using Cisco ASR1000 routers as Sender CE routers, and PIM Registers are encapsulated/decapsulated in hardware on those platforms. But I do agree that it does add overhead.
In fact there was a draft which proposed using MPLS encapsulation in networks that support MPLS to replace the existing RP mechanism.
http://tools.ietf.org/html/draft-bhatia-pim-mpls-register -packets-00
This quite interesting, I hadn't heard of this one before, although I'd always wondered why something like this wasn't already implemented. My main issue with this proposal is that if the Sender CE router is not part of your network, i.e., your customer, a partner network, e.t.c., it requires that your MPLS domain be extended toward them. It's not impossible, but not typically common. Also, it would be good to support both LDP and RSVP, and not RSVP only. Maybe I should contact the author to see if the project can be revived. Cheers, Mark.
Isn't source discovery and efficiency a big concern for ASM? If individual streams are tied to a specific source then it's possible to live without some of the overhead involved in ASM. Joins go straight to the source, traffic is disseminated via direct paths instead of being replicated by the RP, etc etc.. Disclaimer: Other than being a lab rat I haven't done much with multicast in the wild. 2011/12/29 Jeff Tantsura <jeff.tantsura@ericsson.com>
Mike,
To my knowledge in most today's networks even if legacy equipment don't support IGMPv3 most likely 1st hop router does static translation and SSM upstream. The reason not to migrate to SSM is usually - ASM is already there and works just fine :) Cost to support RP infrastructure is usually the main non-technical factor to not to use ASM. Would be interested to hear from the SPs on the list.
Regards, Jeff
On Dec 28, 2011, at 2:19 PM, "Mike McBride" <mmcbride7@gmail.com> wrote:
Marshall,
On Wed, Dec 28, 2011 at 1:50 PM, Marshall Eubanks <marshall.eubanks@gmail.com> wrote:
Dear Mike;
On Wed, Dec 28, 2011 at 4:48 PM, Mike McBride <mmcbride7@gmail.com> wrote:
Anyone using ASM (versus SSM) for IPTV? If so why?
From what I understand, the answer is likely to be "yes" and the reason is likely to be "deployed equipment only supports IGMP v2."
Agreed. I'm seeking confirmation, from IPTV implementers, that non igmpv3 support is the reason for using ASM with IPTV. Versus other reasons such as reducing state. Or is this a non issue and everyone is using SSM with IPTV?
thanks, mike
Regards Marshall
thanks, mike
On Thursday, December 29, 2011 08:02:04 AM Keegan Holley wrote:
Isn't source discovery and efficiency a big concern for ASM? If individual streams are tied to a specific source then it's possible to live without some of the overhead involved in ASM. Joins go straight to the source, traffic is disseminated via direct paths instead of being replicated by the RP, etc etc..
In our case, Source discovery happens once, and BGP updates containing that information is sent to all Receiver PE routers in the MVPN. They then generate Type 7 routes locally (due to running SPT-only mode), which are essentially (S,G) routes. Once a customer sends a Join message to subscribe to a group, the Receiver PE router just serves it locally. No need to send any requests back to the RP. This breaks regular PIM mechanisms, but is a welcome deviation that makes a lot of sense. One does have the option of running RPT-SPT modes which are akin to regular IP Multicast. Mark.
On Thursday, December 29, 2011 07:32:38 AM Jeff Tantsura wrote:
To my knowledge in most today's networks even if legacy equipment don't support IGMPv3 most likely 1st hop router does static translation and SSM upstream.
Yes, SSM Mapping allows for PIM-SSM to be used in a network where the receivers don't support IGMPv3. But it tends to be static in nature, although both Juniper and Cisco suggest that dynamically-configured options are possible. I couldn't quite decode the Juniper dynamic method, but the Cisco one appears to be based on DNS. That should be interesting (and a colossal screw-up if things are poorly maintained): http://www.cisco.com/en/US/docs/ios/12_3t/12_3t2/feature/guide/gtssmma.html#...
The reason not to migrate to SSM is usually - ASM is already there and works just fine :)
This is our case.
Cost to support RP infrastructure is usually the main non-technical factor to not to use ASM. Would be interested to hear from the SPs on the list.
For us, the cost of the RP isn't an issue. The Sender PE routers (in NG-MVPN speak, the ISP's routers that are connected toward the Source) are also the RP's. But due to the use of NG-MVPN, and how we designed our Multicast backbone, there really isn't any need for the Receiver PE routers to contact the RP whenever a customer is joining a group. BGP has been extended to handle PIM messages in NG-MVPN. When a Source is discovered by the Sender PE router, it generates a Type 5 SA-AD (Source Active, Auto-discovery) BGP update route which is sent to all Receiver PE routers participating in the MVPN. This Type 5 route is generated from the PIM Register state that is created by PIM running between the Sender PE and CE routers. If the Receiver PE router is configured to operate the MVPN in the SPT-only mode, it generates a Type 7 (C-S,C-G) route for every Type 5 route it received, effectively creating the necessary state in the local Receiver PE router. Once customers send (*,G) IGMP reports requesting to join Multicast groups, that state is already present on the Receiver PE router, and traffic starts flowing immediately downstream. If the Receiver PE router is configured to operate the MVPN in RPT-SPT mode, it will follow regular PIM mecahnisms when users are trying to join groups, i.e., Join messages are forwarded toward the RP along the RPT, and then Multicast traffic forwarded along the SPT once the correct (C-S,C-G) state is created locally. The above explanation is somewhat simplified, but represents the general architecture of how things work in NG-MVPN's. For us, SPT-only mode makes sense because we have IPTv probes attached to all Receiver PE routers; and since they're collecting telemetry for all IPTv channels, no point running the RPT-SPT mode. Please note that this whole setup doesn't require MSDP, which is nice! Cheers, Mark.
On Thursday, December 29, 2011 06:19:14 AM Mike McBride wrote:
Agreed. I'm seeking confirmation, from IPTV implementers, that non igmpv3 support is the reason for using ASM with IPTV. Versus other reasons such as reducing state. Or is this a non issue and everyone is using SSM with IPTV?
We are running NG-MVPN (BGP replaces PIM, MPLS replaces IP/GRE). We run PIM-SM, not only because our customer's STB's only support IGMPv2 (we only transport IPTv content, not generate it), but also because, well, it just works and there hasn't been any compelling need to push for PIM-SSM. It's scaling well due to the nature of the NG-MVPN infrastructure itself. Mark.
On Wed, 28 Dec 2011, Marshall Eubanks wrote:
From what I understand, the answer is likely to be "yes" and the reason is likely to be "deployed equipment only supports IGMP v2."
That and numerous clients which don't know anything about SSM. Antonio Querubin e-mail: tony@lavanauts.org xmpp: antonioquerubin@gmail.com
On Dec 28, 2011, at 10:55 PM, Antonio Querubin wrote:
On Wed, 28 Dec 2011, Marshall Eubanks wrote:
From what I understand, the answer is likely to be "yes" and the reason is likely to be "deployed equipment only supports IGMP v2."
That and numerous clients which don't know anything about SSM.
For example Apple products don't support IGMPv3. --- Bruce Curtis bruce.curtis@ndsu.edu Certified NetAnalyst II 701-231-8527 North Dakota State University
On Thursday, December 29, 2011 05:50:58 AM Marshall Eubanks wrote:
From what I understand, the answer is likely to be "yes" and the
reason is likely to be "deployed equipment only supports IGMP v2."
This is true for us - the broadcaster whose IPTv traffic we carry supports only IGMPv2. This makes SSM a no-no, but we aren't really complaining about having to use PIM-SM either. Mark.
participants (9)
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Antonio Querubin -
Curtis, Bruce -
Glen Kent -
Jeff Tantsura -
Keegan Holley -
Mark Tinka -
Marshall Eubanks -
Mike McBride -
Olivier Benghozi