From: Jim (quangnn@hptvietnam.com.vn)
Date: Wed May 04 2005 - 08:20:26 GMT-3
Tim,
Thanks for getting back to me,
so which one will sends joins up the tree if 2 routers are on the
shared-media with client?
R1 R2
----|-------|-------
|
client
the proccess of PIM forwarder election works with both pim dense & spare
mode and it happens whenever one of the router receive multicast packets on
its outgoing interface for that packet's group.
When the client sends join message to R2, R2 joins shared tree and the
traffic will flow from source to client this way. But when R2 forwards
traffic with destination address as multicast packets to clients, switch
will treats these packets as broadcast and forward to all other ports. As
the result, R1 receives packets on its outgoing interface for that packet's
group and it immediately starts the proccess of PIM forwarder election by
sending assert message. Finally, the winner will join the shared tree and
take the role of the forwarder for all clients on the shared media.
On TCP/IP vol2 489, we have "the election of designated router on
multiaccess networks are common to PIM-SM and PIM-DM"
Jim.
----- Original Message -----
From: "ccie2be" <ccie2be@nyc.rr.com>
To: "'Jim'" <quangnn@hptvietnam.com.vn>; "'Danshtr'" <danshtr@gmail.com>;
"'Cisco certification'" <ccielab@groupstudy.com>
Sent: Wednesday, May 04, 2005 4:53 PM
Subject: RE: Multicast DR...
> Jim,
>
> I think your remarks are correct only if PIM Dense Mode is being used.
>
> If PIM Sparse Mode is used, then the rtr which sends joins up the tree
> will
> also forward mcast traffic to hosts.
>
> HTH, Tim
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Jim
> Sent: Wednesday, May 04, 2005 5:27 AM
> To: Danshtr; Cisco certification
> Subject: Re: Multicast DR...
>
> On a shared media, the router selected to forward traffic to client is the
> one
>
> i) who advertises lowest metric preference ( in other words, lowest AD)
> ii) who advertises lowest metric if the metric preference is equal
> iii) who has the highest IP address on the network if all other metric are
> the same.
>
> PIM bases on other protocols for its routing so you can verify DR
> selection
> by checking the route to Multicast Source in routing and mroute table.
>
> HTH, Jim
>
> ----- Original Message -----
> From: "Danshtr" <danshtr@gmail.com>
> To: "Cisco certification" <ccielab@groupstudy.com>
> Sent: Wednesday, May 04, 2005 1:47 PM
> Subject: Multicast DR...
>
>
>> Hello
>>
>> Reading through multicast documentation, they are mentioning DR and
>> queriers which both are intended for deciding which router will
>> forward multicast packets to the recievers.
>>
>> But i couldn't find how the routers, on a shared media, decide which
>> one will forward the packets from the source.
>>
>> Does anyone here knows the answer? I am sure there is... because it
>> works!
>>
>> --
>> Best regards,
>> Dan
>>
>> _______________________________________________________________________
>> Subscription information may be found at:
>> http://www.groupstudy.com/list/CCIELab.html
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
This archive was generated by hypermail 2.1.4 : Fri Jun 03 2005 - 10:11:56 GMT-3