From: ricky ong (longwaydown@live.com)
Date: Fri Sep 19 2008 - 11:29:35 ART
Hi Paul,
Thanks for your help and i think i am clearer on the MSDP concept now. BElow is a simple drawing:
sw2--R5--R4--R6--(join 225.26.26.26)
R5 and R4 are configured as anycast RP. The anycast RP address is 150.1.0.255. R4 and R5 is now peering MSDP using anotehr loopback.
I am able to ping from SW2 to multicast group joined on R6 with both R4 and R5 active at the same time now.. and the reason i was not able to earlier on is kinda stupid... I TYPE THE RP-ADDRESS WRONGLY on SW2!!!
So there is no register message received on R5 when Sw2 start the ping, and as what Paul explained, no register message, no MSDP exchange. I was wrong conceptually earlier on about the MSDP thing.. i thought since R4 has a (*,G) for group 225.26.26.26, it should pass this information to R5 through MSDP so that R5 knows where the client is.. but apparently it does not. Only the source information is passed (as the name already suggested). And once R4 knows about the source behind R5, it will join towards the source and R5 will know where to forward the multicast traffic.
Thanks all for the kind advise on this topic! And I also agree with Bogdan that the SG may be wrong by saying multicast will only work if one of the RP is down.
Cheers,
Ricky
> Date: Fri, 19 Sep 2008 13:49:22 +0100> From: paul.cosgrove@heanet.ie> To: longwaydown@live.com> CC: roberto.clavero@telindus.es; bogdan.sass@catc.ro; ccielab@groupstudy.com> Subject: Re: iewb lab 12 Q6.3 anycast rp> > Hi Ricky,> > Can you clarify the topology being used here? I for one do not have the > workbook. > > Multicast routing is not the function of MSDP, MSDP is used to tell RPs > about active sources, mBGP or unicast routing protocols control the RPF > check, PIM (+IGMP at the edges) controls the actual routing of the > multicast packets.> > There are reasons why you may want to configure MSDP on a physical > interface, but in an anycast environment where you control the two (or > more) routers I would not do so as it is likely to decrease resilience. > If you peer with another AS who do not use PMTUD (or you choose not to > yourself) then you might want to use directly connected physical IPs for > peerings to avoid having a very low TCP MSS value.> > MSDP exchan!
ges information about sources which are learned through > received register messages. If the interface you are sourcing multicast > from is adjacent to your RP then there is no register message. Try > sourcing your packets from one hop further away.> > Paul.> > ricky ong wrote:> > Hi Roberto,> > I have reachibility for both the loopback on R4 and R5, i got the MSDP up but no SA exchange.. see the command output:> > > > MSDP Peer 129.1.45.4 (?), AS 100 Connection status: State: Up, Resets: 0, Connection source: Ethernet0/1 (129.1.45.5) Uptime(Downtime): 00:08:35, Messages sent/received: 9/9 Output messages discarded: 0 Connection and counters cleared 00:09:02 ago SA Filtering: Input (S,G) filter: none, route-map: none Input RP filter: none, route-map: none Output (S,G) filter: none, route-map: none Output RP filter: none, route-map: none SA-Requests: Input filter: none Peer ttl threshold: 0 SAs learned from this peer: 0 Input queue size: 0, Output queue size: 0> > > > As a r!
esult, R5 is not passing multicast to groups who registered to!
R4. I h
ave tried to peer using the direct interface address but no luck still. > > > > Hi Bogdan,> > Did you get the MSDP working and sw2 is able to ping groups joined on R6 and registered with R4? You configured the same way as the solution does but still works with 2 RPs up at the same time?> > > > Cheers,> > Ricky> >> >> >> > > >> From: Roberto.Clavero@TELINDUS.ES> To: bogdan.sass@catc.ro; longwaydown@live.com> CC: ccielab@groupstudy.com> Date: Fri, 19 Sep 2008 10:08:20 +0200> Subject: RE: iewb lab 12 Q6.3 anycast rp> > Hi,> From my experience you should to check If loopbacks are reachable from R4 and R5. An also, note that sometimes msdp is established but not working because the msdp id-originator is loopback by default. So I recommend to you change this source of msdp sessions to interfaces using the command ip msdp id-originator.> > Best regards,> Roberto> > -----Mensaje original-----> De: nobody@groupstudy.com [mailto:nobody@groupstudy.com] En nombre de Bogdan Sass> Enviado!
el: viernes, 19 de septiembre de 2008 8:43> Para: ricky ong> CC: ccielab@groupstudy.com> Asunto: Re: iewb lab 12 Q6.3 anycast rp> > ricky ong wrote:> > Hi all,> > I got some problems when working on IEWB VOL2 4.1 LAB 12 Q6.3. The question calls for anycast RP configuration. After configuring i realized that I can ping a mul!> t!> >> > > icast group joined on R6 from SW2 (225.26.26.26). I got the MSDP peer up but it seems that multicast routing table is not exchanged between the two MSDP peer (R4, R5).> > I referred to the solution guide and was a bit surprised to find the below explanation:> >> > "When R4's lo is up, sw2 will not be able to ping 226.26.26.26 since the group is using R4 as RP and sw2 is using R5 as RP."> > Yes this is a problem, but isn't it the reason why MSDP is configured?> >> > "Now we will shutdown R4's lo which will mean R6 will use R5 as the RP "> > How can we provide RP redundancy then if multicast can not flow with two RP up at the same time?> >> >!
> I had the same "problem" while doing the lab. From what I re!
ad about
> anycast RP, this is actually the normal, expected behavior (the> information about sources/clients is passed between the RPs via MSDP, so> any router can ping any multicast group).> > So I can only assume that the SG is wrong on this one.> > --> Bogdan Sass> CCAI,CC!> NP!> > ,CCSP,JNCIA-ER> Information Systems Security Professional> "Cu!> > riosity > >> > was framed - ignorance killed the cat"> > > Blogs and organic groups at http://www.ccie.net> > _______________________________________________________________________> Subscription information may be found at:> http://www.groupstudy.com/list/CCIELab.html> > > Blogs and organic groups at http://www.ccie.net> > _______________________________________________________________________> Subscription information may be found at: > http://www.groupstudy.com/list/CCIELab.html> > > > > > > > > _________________________________________________________________> > Easily edit your photos like a pro with Photo Gallery.> > http://get.li!
ve.com/photogallery/overview> >> >> > Blogs and organic groups at http://www.ccie.net> >> > _______________________________________________________________________> > Subscription information may be found at: > > http://www.groupstudy.com/list/CCIELab.html> > > Blogs and organic groups at http://www.ccie.net> > _______________________________________________________________________> Subscription information may be found at: > http://www.groupstudy.com/list/CCIELab.html> > > > > > >
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