Cisco CCNP / BCMSN Exam Tutorial: Configuring CGMP On Routers & Switches - Computers

If a Layer Two button doesn't possess the skills to run IGMP Snooping, it will be able to perform CGMP - Cisco Group Membership Protocol. CGMP allows the particular multicast router to utilize this Layer Two button to eliminate unnecessary multicast forwarding.

CGMP will be enabled on both multicast router as well as the switch, nevertheless the router's gonna do each of the work. The router is going to be giving Join and Leave messages to the switch as needed. PIM must be running on the actual router program experiencing the switch in advance of permitting CGMP, since you can see:

R1(config)#int e0

R1(config-if)#ip cgmp

WARNING: CGMP requires PIM enabled on interface

R1(config-if)#ip pim sparse

R1(config-if)#ip cgmp

When CGMP is primary made possible on both the multicast router plus switch, your router will give some sort of CGMP Join message, letting this switch than a multicast router is right now linked to it. This special CGMP Join will have a Group Destination Address (GDA) involving 0000.0000.0000 as well as MAC deal with on the submitting interface. The GDA is used to identify this multicast group, therefore when it is set to all or any zeroes, your transition is aware that is a strong introductory CGMP Join, rental the particular switch realize that the actual multicast router can be online.

The switch creates an entry with its MAC table that this router is to be found heli-copter flight port how the CGMP Join followed in on. The router will give some sort of CGMP Join for the move each instant to help serve like a keepalive.

A workstation coupled for the switch upon dock 0/5 now chooses in order to subscribe to multicast team 225.1.1.1. The Join communication can be provided for this multicast router, but very first it'll go through your switch. The button will perform just what exactly you'd be expecting them to complete - study this source MAC address as well as make an obtain for it inside the MAC address kitchen table as being out of port quickly 0/5 in case you will find not a good obtain witout a doubt there. (Don't neglect the fact that MAC correct dining room table is usually furthermore called this CAM dining room table as well as the linking table.)

The router will receive your Join request, plus send out a new CGMP Join back again for the switch. This CGMP Join could have both the multicast group's MAC handle plus your requesting host's MAC address. Now your switch knows with regards to this multicast class 225.1.1.1 and the some sort of fellow member of these party is found off of dock quickly 0/5. In this future, should the button obtains eyeglasses meant for that multicast group, the button will not likely deluge the body since it might a great unidentified multicast. Instead, your change will probably frontward a duplicate with the style to each one vent that it understands ends up in a representative in the multicast group.

Two major advantages of CGMP will be the explicit Join and Leave Group messages. In the particular upcoming component of this specific BCMSN audit tutorial, we shall take a look at your Leave Group messages.

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