Hello,
I have a small basic test topology running EIGRP as IGP, PIM-SM and BSR for RP advertisement. R1 is the c-RP sourcing from looopback and R3 is the c-BSR sourcing from loopback0. R3 is going via R2 to reach the loop0.
I have not found any documentation about BSR router doing RPF check on the unicast Candidate-RP-Advertisement. I have read INE's workbook and some other post that states Candidate-RP-Advertisement packet is subject to RPF, but it does not seem to be correct when I do this lab. I also have a static mroute pointing to another interface to break the RPF but it does not seem to have any effect. Can anyone provide any documents or a source that can confirm this behaviour that I have seen?
Thank you.
R3#show ip route 1.1.1.1
Routing entry for 1.1.1.1/32
Known via "eigrp 100", distance 170, metric 3469653, type external
Redistributing via eigrp 100
Last update from 10.0.23.2 on Ethernet0/1, 00:10:35 ago
Routing Descriptor Blocks:
* 10.0.23.2, from 10.0.23.2, 00:10:35 ago, via Ethernet0/1
Route metric is 3469653, traffic share count is 1
Total delay is 110 microseconds, minimum bandwidth is 1500 Kbit
Reliability 1/255, minimum MTU 1 bytes
Loading 1/255, Hops 1
R3#show running-config | se ip mroute
ip mroute 1.1.1.1 255.255.255.255 10.0.13.1
R3#show ip rpf 1.1.1.1
RPF information for ? (1.1.1.1)
RPF interface: Ethernet1/1
RPF neighbor: ? (10.0.13.1)
RPF route/mask: 1.1.1.1/32
RPF type: multicast (static)
Doing distance-preferred lookups across tables
RPF topology: ipv4 multicast base
R3#show ip pim rp mapping
PIM Group-to-RP Mappings
This system is the Bootstrap Router (v2)
Group(s) 224.0.0.0/4
RP 1.1.1.1 (?), v2
Info source: 1.1.1.1 (?), via bootstrap, priority 200, holdtime 25
Uptime: 00:31:21, expires: 00:00:23
The debug shows that the c-RP message comes in and is being updated.
*Dec 26 20:20:59.159: PIM(0): Received v2 Candidate-RP-Advertisement on Ethernet1/1 from 1.1.1.1
*Dec 26 20:20:59.159: PIM-BSR(0): RP 1.1.1.1, 1 Group Prefixes, Priority 200, Holdtime 25
*Dec 26 20:20:59.159: (0): pim_add_prm:: 224.0.0.0/240.0.0.0, rp=1.1.1.1, repl = 0, ver =2, is_neg =0, bidir = 0, crp = 200
*Dec 26 20:20:59.159: PIM(0): Update
*Dec 26 20:20:59.159: prm_rp->bidir_mode = 0 vs bidir = 0 (224.0.0.0/4, RP:1.1.1.1), PIMv2
