I have a scenario I am trying to get an explanation to regarding 2 PIM DR's
running as anycast RP's attached to a LAN. Basically I cannot understand how
PIM,IGMP operates in the scenario below with the respect to the forwarding
of source traffic from a multi-access segment. The PIM standard states that
the DR will forward traffic onto and off a multi-access segment, but in the
scenario below the non-dr takes over the forwarding of source traffic from
the multi-access segment, when link A fails. Can anyone explain what PIM is
doing is this scenario as I cannot see any procedural details in the PIM
standard.
Thanks in advance
Leon Cozzi
In the following scenario when both A and B links are available both the
source tree and the shared tree are built along link A.
------------
|Pigpen | ip igmp join-group
------------ 239.255.1.1
/ \
/ \
/ \
/ A \B
/ \
/ \
/ \
RP ------------- ------------ RP
1.1.1.1 | Maggie | MSDP | Lisa |
1.1.1.1
--------------- ------------
10.159.71.194 | DR |10.159.71.193
| |
| |
------------------------------------------
Source to 239.255.1.1
The PIM standard states that a DR will forward traffic onto and off a LAN.
In the scenario above, the DR Maggie will forward traffic from its Ethernet
interface and out of link A.
maggie#sh ip mroute active
Active IP Multicast Sources - sending >= 4 kbps
Group: 239.255.1.1, (?)
Source: 10.159.71.150 (?)
Rate: 10 pps/10 kbps(1sec), 10 kbps(last 25 secs), 8 kbps(life avg)
lisa#sh ip mroute active
Active IP Multicast Sources - sending >= 4 kbps
lisa#
When I fail link A, Lisa take over the forwarding of the traffic after
pigpen sends a join up link B.
lisa#sh ip mroute active
Active IP Multicast Sources - sending >= 4 kbps
Group: 239.255.1.1, (?)
Source: 10.159.71.150 (?)
Rate: 10 pps/10 kbps(1sec), 10 kbps(last 36 secs), 2 kbps(life avg)
maggie#sh ip mroute active
Active IP Multicast Sources - sending >= 4 kbps
maggie#
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