Auto-RP Changes 12/9/98 This file explains the use of the 'ip pim accept rp' command and changes to the group-list use for auto-rp which can now advertise a negative prefix range to guarantee that a range of groups will remain in dense mode. ------------------------------------------------------------------------- When multiple "ip pim accept-rp" filters are configured, they must be ordered in the following order: "accept-rp ", ...,"accept-rp auto-rp", "accept-rp 0.0.0.0 ". E.g. the following will accept 171.69.58.88 as the RP for groups in 239.0.0.0/8, and RPs for groups in the Auto-RP cache. If the RP and group don't match the first two filters, the 3rd filter is in effect, i.e. any RP is accepted for groups permitted by ACL 2. ip pim accept-rp 171.69.58.88 1 ip pim accept-rp auto-rp ip pim accept-rp 0.0.0.0 2 access-list 1 permit 239.0.0.0 0.255.255.255 access-list 2 deny 224.0.1.39 access-list 2 deny 224.0.1.40 ---------------------------------------------------------------------- Command Changes [no] ip pim send-rp-announce scope group-list This command sends an Auto-RP RP annoucement message to the well known group CISCO-RP-ANNOUNCE (224.0.1.39). This command should be used in a router you want to be the RP. The RP address field inside the announcement message will contain the IP address from the . is the time-to-live in the IP header which is set. This allows for the announcements to stay inside a ttl scoped boundary. is an access-list describing the group ranges this system is willing to be the RP for. Note that the deny clauses in the are ignored. [11.1] Starting with IOS versions [12.0(1.1)], if the access-list contains a "deny" entry, auto-rp will maintain a negative entry for those group ranges. This will make it easier to configure group ranges to be dense-mode only groups. An RP announcement with a denied group prefix overrides any positive announcements for the same prefix from other RPs. HOWEVER, IOS versions prior to this required a deny clause. The access-list must be changed to remove these deny clauses to obtain the correct RP map. -------------------------------------------------- Auto-RP negative prefix feature. In IOS images starting with 12.0(1.1): The RP map may contain a negative entry that is denoted with a (-) as follows: mm1-25b#sh ip pim rp map PIM Group-to-RP Mappings This system is an RP (Auto-RP) This system is an RP-mapping agent Group(s) (-)224.0.0.0/4 RP 171.69.214.10 (mm1-r7kd.cisco.com), v2v1 Info source: 171.69.214.10 (mm1-r7kd.cisco.com), via Auto-RP Uptime: 00:26:17, expires: 00:00:25 Group(s) 239.254.248.0/24 RP 171.69.214.10 (mm1-r7kd.cisco.com), v2v1 Info source: 171.69.214.10 (mm1-r7kd.cisco.com), via Auto-RP Uptime: 00:26:17, expires: 00:02:24 The above entry is obtained by mistakenly configuring the following on the RP announcing the RP. ip pim send-rp-announce Ethernet3/0 scope 15 group-list 95 ip pim send-rp-discovery scope 15 ! ! access-list 95 permit 239.254.248.0 0.0.0.255 access-list 95 deny any The deny entry in this access list was required in previous IOS images. "deny any" means the entire multicast address space is to be treated in dense mode. The deny entry must be removed in images after 12.0(1.1) if you want to announce an RP on a different router for the range covered by the deny clause. .