From: kieren.carter@postremo.co.uk
Date: Mon Nov 22 2004 - 13:01:33 GMT-3
Hi all,
I wonder if someone could shed a bit of light on the use of the ip pim rp-announce-filter command within Cisco Auto-RP.
I have a very basic network setup for testing consisting of three routers connected via serial connections as shown below (this is part of a bigger test network, thats why there is R3, R4 and R2):
(R3)-----------/ \-----------(R2)
/-------------(R4)-------------\
I am using Loopbacks on all routers with the following IP addresses:
R2 Loopback Interface = 10.0.52.1/24
R3 Loopback Interface = 10.0.53.1/24
R4 Loopback Interface = 10.0.54.1/24
All of the interfaces on the router are configured with ip pim sparse-dense-mode.
I have configured R2 and R3 as Candidate RPs and R4 is configured as the RP mapping agent. Below is the configuration for both R2 and R3 allowing them to advertise themselves as RPs:
R2:
!
ip multicast-routing
!
ip pim send-rp-announce Loopback0 scope 6 interval 10
!
R3:
!
ip multicast-routing
!
ip pim send-rp-announce Loopback0 scope 6 group-list 10 interval 10
!
access-list 10 permit 224.0.0.0 0.255.255.255
access-list 10 permit 224.0.0.0 15.255.255.255
Each of the cRPs advertises out every 10 seconds for the ease of troubleshooting. On R3 I have configured the cRP so that it will advertise out itself as a cRP for 224.0.0.0/8 and 224.0.0.0/4. On the mapping agent I want to filter the cRPs so that it will only consider R2 (10.0.52.1) as a cRP for the range 224.0.0.0/4 but Im not having much luck getting this to work as expected. The configuration for the R4, the mapping agent is:
R4:
ip multicast-routing
!
ip pim rp-announce-filter rp-list 10 group-list 11
ip pim send-rp-discovery Loopback0 scope 5
!
access-list 10 permit 10.0.53.1
access-list 11 permit 224.0.0.0 0.255.255.255
access-list 11 deny 224.0.0.0 15.255.255.255
The ip pim rp-announce-filter identifies any of the cRP that I want to apply a filter to, in this case I only want to tie a filter to 10.0.53.1 (R3). The filter I want to apply is given in the group-list, highlighting that I want to permit this router as a cRP for 224.0.0.0/8 but deny it as a cRP for the range 224.0.0.0/4. Unfortunately, it doesnt seem to be working as desired, the debugging for the auto-rp announcements shows that 10.0.53.1 (R3) is sending an RP-announce message for 224.0.0.0/4 and 224.0.0.0/8 and both of these and both are being accepted:
R4#debu ip pim auto-rp
PIM Auto-RP debugging is on
R4#clear ip pim rp-mapping
03:07:52: Auto-RP: Received RP-announce, from 10.0.52.1, RP_cnt 1, ht 31
03:07:52: Auto-RP: Update (224.0.0.0/4, RP:10.0.52.1), PIMv2 v1
03:07:52: Auto-RP: Received RP-announce, from 10.0.52.1, RP_cnt 1, ht 31
03:07:52: Auto-RP: Update (224.0.0.0/4, RP:10.0.52.1), PIMv2 v1
03:07:52: Auto-RP: Received RP-announce, from 10.0.52.1, RP_cnt 1, ht 31
03:07:52: Auto-RP: Update (224.0.0.0/4, RP:10.0.52.1), PIMv2 v1
03:07:59: Auto-RP: Received RP-announce, from 10.0.53.1, RP_cnt 1, ht 31
03:07:59: Auto-RP: Update (224.0.0.0/8, RP:10.0.53.1), PIMv2 v1
03:07:59: Auto-RP: Update (224.0.0.0/4, RP:10.0.53.1), PIMv2 v1
03:07:59: Auto-RP: Received RP-announce, from 10.0.53.1, RP_cnt 1, ht 31
03:07:59: Auto-RP: Update (224.0.0.0/8, RP:10.0.53.1), PIMv2 v1
03:07:59: Auto-RP: Update (224.0.0.0/4, RP:10.0.53.1), PIMv2 v1
03:07:59: Auto-RP: Received RP-announce, from 10.0.53.1, RP_cnt 1, ht 31
03:07:59: Auto-RP: Update (224.0.0.0/8, RP:10.0.53.1), PIMv2 v1
03:07:59: Auto-RP: Update (224.0.0.0/4, RP:10.0.53.1), PIMv2 v1
03:07:59: Auto-RP: Received RP-announce, from 10.0.53.1, RP_cnt 1, ht 31
This means that R3 is winning the RP election based on IP address for 224.0.0.0/4 as shown below:
R4#show ip pim rp mapping
PIM Group-to-RP Mappings
This system is an RP-mapping agent (Loopback0)
Group(s) 224.0.0.0/8
RP 10.0.53.1 (?), v2v1
Info source: 10.0.53.1 (?), elected via Auto-RP
Uptime: 00:03:27, expires: 00:00:23
Group(s) 224.0.0.0/4
RP 10.0.53.1 (?), v2v1
Info source: 10.0.53.1 (?), elected via Auto-RP
Uptime: 00:03:27, expires: 00:00:23
RP 10.0.52.1 (?), v2v1
Info source: 10.0.52.1 (?), via Auto-RP
Uptime: 00:03:24, expires: 00:00:26
I have played around with this command for a while, but I cant seem to get the filtering to work as I want it to. For example, I changed access-list 11 on R4 to:
access-list 11 deny 224.0.0.0 0.255.255.255
access-list 11 permit 224.0.0.0 15.255.255.255
The idea being that the 224.0.0.0/8 would be filtered and the 224.0.0.0/4 would be accepted, but instead both of the groups get filtered leaving only R2 (10.0.52.1) as a cRP:
R4#
03:27:19: Auto-RP: Received RP-announce, from 10.0.53.1, RP_cnt 1, ht 31
03:27:19: Auto-RP: Filtered 224.0.0.0/8 for RP 10.0.53.1
03:27:19: Auto-RP: Filtered 224.0.0.0/4 for RP 10.0.53.1
03:27:19: Auto-RP: Received RP-announce, from 10.0.53.1, RP_cnt 1, ht 31
03:27:19: Auto-RP: Filtered 224.0.0.0/8 for RP 10.0.53.1
03:27:19: Auto-RP: Filtered 224.0.0.0/4 for RP 10.0.53.1
03:27:19: Auto-RP: Received RP-announce, from 10.0.53.1, RP_cnt 1, ht 31
03:27:19: Auto-RP: Filtered 224.0.0.0/8 for RP 10.0.53.1
03:27:19: Auto-RP: Filtered 224.0.0.0/4 for RP 10.0.53.1
03:27:19: Auto-RP: Received RP-announce, from 10.0.53.1, RP_cnt 1, ht 31
R4#show ip pim rp mapping
PIM Group-to-RP Mappings
This system is an RP-mapping agent (Loopback0)
Group(s) 224.0.0.0/4
RP 10.0.52.1 (?), v2v1
Info source: 10.0.52.1 (?), elected via Auto-RP
Uptime: 00:01:34, expires: 00:00:26
Has anyone came across this issue before or am I missing something very basic.
This could be be an IOS specific problem (IOS 12.2(24a) is used on the routers at the moment).
I wanted to include as much information as possible so hope post isn't too big!
Thanks in advance to anyone who is able shed light on this one :-)
cheers
Kieren
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