[j-nsp] no inet.2 for multicast RPF etc. by default?

Pekka Savola pekkas at netcore.fi
Tue Apr 15 10:58:28 EDT 2003


It seems to me that Juniper does not use inet.2 at all by default.

That is, even if I configure routes for inet.2 or use MBGP to distribute 
multicast routes when unicast/multicast topology is not congruent, Juniper 
only uses inet.0 by default.

This seems *odd*.  The desired behaviour should be to always look for
inet.2 first, and if it fails, look at inet.0 (or so I've been believing).  
Otherwise, being transit using MBGP (for example) would likely break RPF
quite badly.

Am I missing something?

Configure PIM RPF Routing Table
By default, PIM uses inet.0 as its Reverse Path Forwarding (RPF) routing
table group. PIM uses an RPF routing table group to resolve its RPF
neighbor for a particular multicast source address and to resolve the RPF
neighbor for the RP address. PIM can optionally use inet.2 as its RPF
routing table group. To do this, add the rib-groups statement at the [edit
routing-options] hierarchy level.

routing-options {
    rib-groups {
        pim-rg {
            import-rib inet.2;
protocols {
    pim {
        rib-group inet pim-rg;
blah at foo> show route x.y.0.0 

inet.0: 153 destinations, 215 routes (152 active, 0 holddown, 1 hidden)
+ = Active Route, - = Last Active, * = Both

x.y.0.0/16     *[BGP/170] 16:10:57, MED 0, localpref 200, from
                      AS path: 65300 I
                    > to a.b.c.177 via ge-1/0/0.0

inet.2: 130 destinations, 180 routes (129 active, 0 holddown, 1 hidden)
+ = Active Route, - = Last Active, * = Both

x.y.0.0/16     *[BGP/170] 5d 02:15:43, MED 0, localpref 50, from
                      AS path: 65300 I
                    > to a.b.c.1 via fe-0/3/1.0
                      to a.b.c.25 via fe-0/3/3.0

blah at foo> show multicast rpf x.y.0.0    
Multicast RPF table: inet.0, 153 entries

    Protocol: BGP
    Interface: ge-1/0/0.0

Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings

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