SMI? EMI? Which to buy? 1

[kmcferrin]

I think the title says it all. What is the difference between SMI and EMI, and do I need either? All I know at this point is that SMI is Standard Multilayer Image and EMI is Enhanced Multilayer Image, and that EMI costs more. But what does it get me?

 

[ADB100]

I assume you mean either 3550, 3560 or 3750 series switches?

EMI has support for routing protocols OSPF, EIGRP, ISIS & BGP - whereas the SMI only supports RIP & Static routes. The EMI image also supports Multicast routing, the SMI only support IGMP snooping so requires an external router to forward multicast.

Other than that they are the same. I think there is a page on CCO detailing this but I can't find it.....

I think the image you require depends on where the switch is to be positioned in the network. I have deployed 3550's as purely access layer switches and so all the routing functionality was handled in the Distribution & Core layers. I have also deployed 3750 & 3550 switches as routers running the EMI (IP Services) image.
If money is not an issue I would go for the EMI image so the features are available if needed either from day-1 or later on.

HTH

Andy

 

[kmcferrin]

Thanks! That helps quite a bit.

 

[KiscoKid]

Just expanding on what the previous poster outlined but the following is a full list of what you get with EMI that is not available with SMI

• Advanced IP routing protocols for load balancing and constructing scalable LANs:

–Open Shortest Path First (OSPF)

–Interior Gateway Routing Protocol (IGRP) and Enhanced IGRP (EIGRP)

–Border Gateway Protocol (BGP) version 4

• WCCP to allow switch interaction with a cache for the purpose of redirecting content requests to a cache and performing basic load balancing across multiple caches

• PBR to allow specific policies to be implemented by causing selective traffic to take different paths

• Protocol-Independent Multicast (PIM) for IP multicast routing within a network that enables the network to receive the multicast feed requested and for switches not participating in the multicast to be pruned-support for PIM sparse mode (PIM-SM), PIM dense mode (PIM-DM), and PIM sparse-dense mode

• Distance Vector Multicast Routing Protocol (DVMRP) tunneling for interconnecting two multicast-enabled networks across non multicast networks