Cisco Ex SERIES Manuel d'utilisateur télécharger pdf (Page 41)

Juniper Networks/Cisco Systems Switch Interoperability Cookbook

! ! !

command is “show port-channel summary”. Again, no MC-LAG awareness or

configuration is required on either Cisco switch.

Multicast&routing&

Objective!

To verify the ability of a network comprised of Juniper and Cisco devices to learn

multicast routing information using the PIM-SM protocol.

To verify the ability of a network comprised of Juniper and Cisco devices to correctly

forward multicast traffic based on routing information learned via PIM-SM.

Background!

Protocol Independent Multicast-Sparse Mode (PIM-SM) is a popular choice for multicast

routing. Devices running PIM-SM can learn topology information from other PIM-SM

routers and make forwarding decisions based on that information.

Like all multicast protocols, PIM-SM uses reverse path forwarding (RPF) lookups to

determine which router interface is closest to the multicast source. Because PIM-SM does

not include a mechanism to populate an RPF table, it relies on a unicast routing protocol

such as Open Shortest Path First (OSPF) or Intermediate System-to-Intermediate System

(IS-IS) for this purpose.

Topology!

This example is similar to that used in the “IP multicast switching” section, with one

important change: Here, both Juniper and Cisco devices act as routers running PIM-SM

and OSPF. There are no switches, and therefore no IGMP snooping, in this scenario.

In this example, a video server generates multicast traffic to one subnet of a Juniper

Virtual Chassis (comprised of two Juniper EX9208s). The Juniper device uses PIM-SM

to propagate routing information about that network to other networks, including one in

which a Cisco Catalyst 3850 switch, also running PIM-SM, is attached.

Both the Juniper and Cisco devices use PIM-SM and OSPF to propagate routing

information. Multicast subscribers attached to routed interfaces, each in a different IP

subnet, receive traffic from the streaming video server. The subscriber interfaces also use

IGMP (not IGMP snooping) to build a multicast forwarding table.

Figure 9 illustrates the topology used to validate IP multicast routing functionality. PIM-

SM and OSPF routing is enabled on both Juniper and Cisco devices.

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Cisco Ex SERIES Manuel d'utilisateur Page 41