[Xorp-users] multicast over GRE tunnel

[Christian Lyra]

Hi there,

	I´d like to setup a xorp router to do multicast over a GRE tunnel. My 
setup is like this:

[multicast_enabled_net]----[Cisco-Router]---[no-multicast_net]--[xorp_router]---[desktops]

	Between Cisco-router and xorp_router there´s a GRE tunnel so I can 
trasverse the non_multicast_net. The protocol used is PIM-SM and there
´s a "static" RP on multicast_enabled_net.

	I´m sure that all the other parts are ok, because I had a cisco 2500 in 
the place of xorp_router and it work just fine with a simple config 
like this one:

ip multicast-routing
interface Tunnel1
 ip address 200.x.x.154 255.255.255.252
 ip pim sparse-mode
 tunnel source 200.y.y.191
 tunnel destination 200.y.y.9

ip pim rp-address 200.z.z.z
ip mroute 0.0.0.0 0.0.0.0 tunnel0

	I tried to emulate this same configuration with xorp:

xorp at teste# show
    protocols {
        igmp {
            interface eth0 {
                vif eth0 {
                    query-interval: 30
                }
            }
            interface tun0 {
                vif tun0 {
                }
            }
        }
        pimsm4 {
            interface "register_vif" {
                vif "register_vif" {
                }
            }
            interface tun0 {
                vif tun0 {
                }
            }
            interface eth0 {
                vif eth0 {
                }
            }
            static-rps {
                rp 200.z.z.z {
                    group-prefix 224.0.0.0/4 {
                    }
                }
            }
        }
        static {
            route 0.0.0.0/0 {
                next-hop: 200.x.x.x
            }
            mrib-route 0.0.0.0/0 {
                next-hop: 200.x.x.153 /* tunnel */
}
        }
    }
    fea {
        unicast-forwarding4 {
        }
    }
    interfaces {
        interface eth0 {
            vif eth0 {
                address 200.x.x.191 {
                    prefix-length: 24
                }
            }
        }
        interface lo {
            vif lo {
            }
        }
        interface tun0 {
            vif tun0 {
                address 200.x.x.154 {
                    prefix-length: 30
                    multicast-capable: true
                }
            }
        }
    }
    plumbing {
        mfea4 {
            interface eth0 {
                vif eth0 {
                }
            }
            interface "register_vif" {
                vif "register_vif" {
                }
            }
	interface tun0 {
                vif tun0 {
                }
            }
        }
    }


	One thing that I noticed is this:
xorp at teste> show pim neighbors
Interface    DRpriority NeighborAddr    V Mode   Holdtime Timeout
tun0                  1 200.x.x.153   2 Sparse      105      82


	But Cisco doesnt see the xorp as a neighbor! (when using the cisco 2500 
instead of xorp, this Cisco router sees two neighbors, one is the 
upstream one and the other the 2500).

bb3#show ip pim neighbor
PIM Neighbor Table
Neighbor          Interface                Uptime/Expires    Ver   DR
Address                                                            
Prio/Mode
<wanip>     FastEthernet1/1/0        04:14:05/00:01:39 v2    N /


	Maybe I´m missing something.... or this can be compatibility problem 
between xorp and cisco? Any clues? I can see the PIM join messagens 
going out from tunnel interface.

	Btw... the xorp is running in a debian sarge. Kernel from distro, and a 
little script to create the tun interface before the xorp_rtmgr is 
started:

ip tunnel add tun0 mode gre remote 200.ci.s.co local 200.lo.ca.l dev 
eth0

ifconfig tun0 allmulti
ifconfig tun0 multicast


-- 
Christian Lyra
POP-PR - RNP

http://lyra.soueu.com.br

  ``The rules of programming are transitory; only Tao is eternal. 
Therefore you must contemplate Tao before you receive enlightenment.'' 
  ``But how will I know when I have received enlightenment?'' asked the 
novice. 
  ``Your program will then run correctly,'' replied the master. 
						The Tao Of Programing