Listing data for an active multicast group
Syntax:
show ip mroute [group-addr ][ source-addr]
Lists data for the specified multicast flow (single-group pair.)
Data output list
- Group address
The multicast group IP address for the specific flow.
- Source address
The source IP address for the specific flow.
- Neighbor
Lists the IP address of the upstream next-hop router running PIM-SM; that is, the router from which the router is receiving datagrams for the current multicast group. This value is
0.0.0.0if the router has not detected the upstream next-hop router's IP address. This field is empty if the multicast server is directly connected to the router.- VLAN
The interface on which the router received the multicast flow.
- Up time (sec)
The elapsed time in seconds since the router learned the information for the current instance of the indicated multicast flow. Note that on an Originator router when a forwarding flow moves to a non-forwarding state (i.e. when pruned) the Up time value for that flow is reset to 0.
- Expire Time (sec)
An mroute which is in a forwarding state — one which represents an active, connected flow for which there are downstream routers and/or locally connected hosts interested in the flow — does not expire. When other PIM-SM routers or locally connected hosts are no longer interested in an active flow, the related mroute on a DR moves to a blocking state, and an mroute in this state does not expire either. In both cases the mroute is only removed from the system when it is no longer needed and so the displayed value for expire time in these situations is not meaningful.
For an mroute on a DR router whose flow is no longer active — including mroutes on non-DR routers whose flow has been pruned — expire time indicates when the mroute entry will eventually be cleared.
Note that flows that are registered with an RP router but are not connected downstream (one for which there is no entry displayed in the neighbor field on the RP) will also have an mroute entry that does not expire.
- Multicast routing protocol
Identifies the IP multicast routing protocol through which the current flow was learned.
- Unicast routing protocol
Identifies the IP routing protocol through which the router learned the upstream interface for the current multicast flow. The listed protocol will be one of connected, static, rip, ospf or other.
- Metric
Indicates the path cost upstream to the multicast source. Used when multiple multicast routers contend to determine the best path to the multicast source. The lower the value, the better the path.
- Metric pref
Used when multiple multicast routers contend to determine the path to the multicast source. When this value differs between routers, PIM selects the router with the lowest value. If Metric pref is the same between contending multicast routers, then PIM selects the router with the lowest metric value to provide the path for the specified multicast traffic. (Different vendors assign differing values for this setting.)
- Assert timer
The time remaining until the router ceases to wait for a response from another multicast router to negotiate the best path back to the multicast source. If this timer expires without a response from any contending multicast routers, then the router assumes it is the best path, and the specified multicast group traffic will flow through the router.
- RPT-tree
A
Yessetting indicates the route is using the RPT. ANosetting indicates the route is using the applicable SPT.
Downstream interfaces
For each downstream interface the following information is shown:
- VLAN
Lists the
vidof the VLAN the router is using to send the outbound packets of the current multicast flow to the next-hop router:- State
Indicates whether the outbound VLAN and next-hop router for the current multicast flow are receiving datagrams.
- Pruned
The router has not detected any joins from the current multicast flow and is not currently forwarding datagrams in the current VLAN.
- Forwarding
The router has received a join for the current multicast flow and is forwarding datagrams in the current VLAN.
- Up Time (sec)
Indicates the elapsed time in seconds since the router learned the displayed information about the current multicast flow.
- Expire Time (sec)
Downstream interface entries for an mroute in PIM-SM are only created when those interfaces become joined for the mroute's flow. Unless join state is periodically refreshed, a downstream interface will eventually move from forwarding to pruned. When forwarding,
Expire Timeindicates when the router expects forwarding to end unless another join for the flow is received. After moving to prune state, the downstream interface entry will last for a short while longer, indicated byExpire Time, before being removed completely.
Route entry data for a specific multicast group
The neighbor field indicates that the router is receiving multicast traffic from a neighboring PIM router. A blank neighbor field indicates that the multicast source is directly connected to the router instead of another PIM router.
switch(config)# show ip mroute 239.255.12.42 10.0.0.10 IP Multicast Route Entry Group Address : 239.255.12.42 Source Address : 10.0.0.10 Neighbor : VLAN : l0 Up Time (sec) :940 Expire Time (sec) :285 Multicast Routing Protocol : PIM-SM Unicast Routing Protocol : connected Metric : 1 Metric Pref : 0 Assert Timer : 0 RP tree : No Downstream Interfaces VLAN State Up Time (sec) Expire Time (sec) ---- ---------- ----------------- ------------------ 20 forwarding 940 204
Showing route entry data for a registered, non-forwarding flow
Blank neighbor and unicast routing protocol fields indicate the special registered, non-forwarding RP condition.
switch(config)# show ip mroute 239.255.12.42 10.0.0.10 IP Multicast Route Entry Group Address : 239.255.12.42 Source Address : 10.0.0.10 Neighbor : VLAN : 20 Up Time (sec) :0 Expire Time (sec) :0 Multicast Routing Protocol : PIM-SM Unicast Routing Protocol : Metric : 0 Metric Pref : 0 Assert Timer : 0 RP tree : No Downstream Interfaces VLAN State Up Time (sec) Expire Time (sec) ---- ---------- ----------------- ------------------