Multicast routing 3750G switch

[sugankarthik]

Hi

am going to configure multicast routing in out 3750G switch, since we are going to install citrix web.

do I need to configure as follows if I miss some thing can any please help me. while do this will there be any slight out age on this

DA-3750-1(config)# interface Vlan3
description 10.10.6.0/23 Network
ip address 10.10.6.1 255.255.254.0
no ip redirects
no ip unreachables
ip pim sparse-mode
ip cgmp

DA-3750-1(config)#ip multicast routing

Thanks

[David Kosich]

Hello,

Besides enabling multicast globally and enabling sparse mode on the vlan interface as you have, you will need need to also configure a RP (rendevous point) globally, since you are using pim sparse mode (ip pim rp-address x.x.x.x). Also, to enable multicast routing globally on the 3750G, you would use the following command:

ip multicast-routing distributed

You would be better served using igmp to constrain the multicast, instead of CGMP. IGMP is enabled by default on cisco switches. CGMP is very rarely used anymore.

Do you only need  the Multicast in a single VLAN? You would only need to use PIM if you plan on routing the mulitcast traffic. If you only need the multicast in a single VLAN, please take a look at the below link, you would only need an IGMP querier if that is the case.

http://www.cisco.com/en/US/products/hw/switches/ps708/products_tech_note09186a008059a9df.shtml

- David Kosich

LAN SWITCHING TAC

[sugankarthik]

Hi David

Thanks for your help

we have multiple VLANS, but am going to apply only one VLAN. this is located at DR. already we have multicast at our office. since it is located in different location do I need to assign RP with different address. below is our current config

ip pim rp-address 10.10.10.1
ip pim send-rp-announce Vlan10 scope 16
ip pim send-rp-discovery Vlan10 scope 16

Thanks

[David Kosich · Accepted solution]

If you have mutliple VLANs, but only require the multicast traffic in a single VLAN, using an IGMP snooping querier might be easier. However, if you route the traffic between VLANs you will need to use PIM.

With PIM sparse mode as you have, you can just use the same RP that you have elsewhere, but each switch doing the multicast routing would 1) need to be able to reach the ip address you are using as the RP 2)needs to have the RP configured on the device, as each device doing the multicast routing must know who the RP is.

- Dave

[sugankarthik]

Thanks Dave