L3-aware IGMP snooping switch

Unanswered Question
Sep 21st, 2010

This is a follow-up to this thread: https://supportforums.cisco.com/message/3178789#3178789

Some documents mention certain access switches have L3-aware ASIC's that can snoop the IGMP packets w/o crushing the switch CPU.

Does anyone know where I can find a matrix table that shows which switch models support this feature?

For example, a few of our remote locations still have 3550's...can we run IGMP snooping on those w/o causing the CPU to spike?

I have this problem too.
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Jon Marshall Wed, 09/22/2010 - 03:01

huangedmc wrote:

This is a follow-up to this thread: https://supportforums.cisco.com/message/3178789#3178789

Some documents mention certain access switches have L3-aware ASIC's that can snoop the IGMP packets w/o crushing the switch CPU.

Does anyone know where I can find a matrix table that shows which switch models support this feature?

For example, a few of our remote locations still have 3550's...can we run IGMP snooping on those w/o causing the CPU to spike?

You are right in what you say in that if the switch does not support IGMP snooping in hardware then it can have a significant impact on the switch CPU. Some of the older switches did not have hardware but all the later Cisco switches should have hardware support.

The 3550 does support IGMP snooping in hardware so that shouldn't be an issue for you.

If you want to find out for all your L3 switch types you need to look at the datasheets but the 3560/3750 both have hardware support as well.

Were there any specific L3 switches you were thinking of other than the 3550 ?

Jon

huangedmc Wed, 09/22/2010 - 05:39

thanks Jon.

Is IGMP snooping in hardware only supported on L3 switches, or L2 ones as well?

We utilize many different models in the access layer in the enterprise...2900/3500XL, 2950/2960, 3550/3560, & 4500.

I'm mostly concerned w/ the XL's, and the 2950...any idea if they can do hardware IGMP snooping?

Jon Marshall Wed, 09/22/2010 - 06:01

huangedmc wrote:

thanks Jon.

Is IGMP snooping in hardware only supported on L3 switches, or L2 ones as well?

We utilize many different models in the access layer in the enterprise...2900/3500XL, 2950/2960, 3550/3560, & 4500.

I'm mostly concerned w/ the XL's, and the 2950...any idea if they can do hardware IGMP snooping?

2950 datasheet says it supports IGMP v3 in hardware although it says nothing about IGMP v2.

The 2900 and 3500XL are more likely not to. I will have a search around to see if i can find a definitive answer.

What supervisor are you running in your 4500s ?

Jon

huangedmc Wed, 09/22/2010 - 07:22

We have Sup II+/3/4/5 on our 4500's running IOS.

According to the matrix table that Lei provided (thank you), IGMP snooping is supported.

However, I'm interested in finding out what models support it in hardware...

I too saw that the datasheet for 2950 specifically says it's supported in hardware, but the one for 2960 doesn't mention it.

Since it's a newer generation of switch, I assume it's supported.

Wish Cisco could've spelled it out in the datasheet on hardware support...

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