From: Alexis Dacquay (alexis.dacquay@gmail.com)
Date: Mon Apr 21 2008 - 18:19:09 ART
Hi,
The general rule between the cRP and the MA is that the cRP
advertisements should match the MA annouce-filter.
However the MA seems ignoring the subnet mask when comparing subnets
which are on the same classless range; and only in that case. Is that
on purpose? I suppose yes it is, a feature... But I haven't seen that
documented on the CCO or explained in the GS archives. I have tried on
two different platform (2800 & 3600), each running a 12.4.
The following example shows "cRP /6" versus "AM /8", but the same
occurs with "cRP /6" versus "AM /4".
Could someone explain this flexibility of the MA regarding the subnet
mask for subnets of same classless range?
! ### Config: R1 (1.1.1.1) is a cRP : advertise a /6 ###
access-list 1 permit 224.0.0.0 3.255.255.255
ip pim send-rp-announce l0 scope 5 group-list 1 interval 10
!
! ### Config: R2 is a MA : accept a /8 ###
ip pim send-rp-discovery Loopback0 scope 5
ip pim rp-announce-filter rp-list 1 group-list 11
!
access-list 1 permit 1.1.1.1
access-list 11 permit 224.0.0.0 0.255.255.255
access-list 11 deny any
!
### Outputs on R2: The MA receives a /6 ###
R2 # debug ip pim auto-rp
*Apr 21 21:35:09.000: Auto-RP(0): Received RP-announce, from 1.1.1.1,
RP_cnt 1, ht 31
*Apr 21 21:35:09.004: Auto-RP(0): Update (224.0.0.0/6, RP:1.1.1.1), PIMv2 v1
### Outputs on R2: The MA matches a received /6 against a configured /8 !! ###
R2#sh access-list
Standard IP access list 1
10 permit 1.1.1.1 (2 matches)
Standard IP access list 11
10 permit 224.0.0.0, wildcard bits 0.255.255.255 (2 matches)
20 deny any
### Outputs on R2: The MA install the RP for a /6 ###
R2#sh ip pim rp mapping
PIM Group-to-RP Mappings
This system is an RP-mapping agent (Loopback0)
Group(s) 224.0.0.0/6
RP 1.1.1.1 (?), v2v1
Info source: 1.1.1.1 (?), elected via Auto-RP
Uptime: 00:05:38, expires: 00:00:21
Regards,
Alexis
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http://www.certscience.com/CCIE
This archive was generated by hypermail 2.1.4 : Thu May 01 2008 - 08:25:51 ART