lrtc
join:2004-06-05
Toronto
edit:
May 4th, @01:56PM
| PIM-SM and SPT
When pim-sm reaches the threshold value it will send a pim join msg towards the source to create SPT. But this SPT is based on unicast routing table is it not? It will also follow any MPLS paths that have been setup right? |
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rolande
Certifiable
Premium,Mod
join:2002-05-24
Powell, OH
clubs:
Host:
Linksys
AT&T Midwest
| You are correct on the first statement. Unicast routing determines the shortest path back towards the source. The default threshold is a handful of packets if not instantaneous for the SPT join to occur. I am not sure about the MPLS behavior but I believe you have to have an MVPN configured before Multicast will be aware of this path information. Otherwise it can only use the unicast routing information to build its tree.
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Ignorance is temporary...stupidity lasts forever!
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belushi
Premium,MVM
join:2000-11-08
Twinsburg, OH
| reply to lrtc
Funny you ask about multicasting, it's my weakest subject in my CCIE endeavors. I really needed to clamp down on it before I went too much further. IPv6 is next. You are the first person I can remember that has asked about it in these forums, although I'm sure there have been others.
As for your question, Rolande seems to have answered right on. MVPNs must be setup for multicasting to work in a MPLS VPN environment. The "regular" network's multicast process is segmented in a way from the MPLS network who is in fact running his/her own multicasting within the cloud. |
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rolande
Certifiable
Premium,Mod
join:2002-05-24
Powell, OH
clubs:
Host:
Linksys
AT&T Midwest
| said by belushi  :Funny you ask about multicasting, it's my weakest subject in my CCIE endeavors. I really needed to clamp down on it before I went too much further. Not to send this thread off track but... Gotta keep up with your brother, eh?  Good luck with your studying. For some reason multicast always clicked with me and it was one of my strongest subjects. It also helped that Cisco gave us a 2 day Multicast lab class. I learned a few more tricks about multicast high availability that I never really experimented with in my own studies.
I've been spending time with the CCIE Security material and figure it is time to try and get a second one on the resume. Baby #3 arrives in less than 2 weeks so that will delay those plans until at least the Fall.
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Ignorance is temporary...stupidity lasts forever!
»www.thewaystation.com/
»blog.thewaystation.com/ |
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