Differences between 3550-24-SMI and 3550-24-EMI

Discussion in 'Cisco' started by JohnNews, Oct 18, 2003.

  1. JohnNews

    JohnNews Guest

    Folks:


    Here are a few quick questions about the differences between 3550-24-SMI and
    3550-24-EMI. One vendor told me it is PERFECTLY OK to purchase 3550-24-SMI
    (at a lower cost that EMI) and upgrade same to the 3550-24-EMI which can
    then be used for CCNP/CCIE studies. I am trying to determine if there are
    any DOWNSIDES to this approach.

    * What are the main differences between 3550-24-SMI and 3550-24-EMI ?
    * Is it OK to purchase a Catalyst 3550-24-SMI at a lower cost and upgrade
    to 3550-24-EMI for use in CCNP/CCIE Lab ?
    * Is it true that these two Catalyst Switches have identical hardware but
    different IOS ?
    * If I upgrade the SMI to EMI do I then have a device identical (in
    software & hardware) to an original Catalyst 3550-24-EMI ?



    Thanks,
    John
     
    JohnNews, Oct 18, 2003
    #1
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  2. JohnNews wrote:
    > Folks:
    >
    >
    > Here are a few quick questions about the differences between 3550-24-SMI and
    > 3550-24-EMI. One vendor told me it is PERFECTLY OK to purchase 3550-24-SMI
    > (at a lower cost that EMI) and upgrade same to the 3550-24-EMI which can
    > then be used for CCNP/CCIE studies. I am trying to determine if there are
    > any DOWNSIDES to this approach.
    >
    > * What are the main differences between 3550-24-SMI and 3550-24-EMI ?


    The EMI enables a richer set of enterprise-class features, including
    hardware-based IP Unicast routing (Open Shortest Path First [OSPF],
    Interior Gateway Routing Protocol [IGRP], Enhanced IGRP [EIGRP], Border
    Gateway Protocol Version 4 [BGPv4]), multicast routing, and policy-based
    routing [PBR]).
    Both the SMI and the EMI allow for Layer 3 and Layer 4 lookups for QoS
    and security

    The following features and functions are supported with the EMI:

    * Dynamic IP routing protocols for load balancing and constructing
    scalable LANs:
    *
    o OSPF
    o IGRP and EIGRP
    o BGPv4
    * Equal-cost routing for load balancing and redundancy
    * Fallback bridging for forwarding of non-IP traffic between two or
    more VLANs
    * 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 nonmulticast networks
    * PBR, which allows superior control by enabling flow redirection
    regardless of the routing protocol configured



    > * Is it OK to purchase a Catalyst 3550-24-SMI at a lower cost and upgrade
    > to 3550-24-EMI for use in CCNP/CCIE Lab ?


    its ok. for ccnp you dont need EMI image

    > * Is it true that these two Catalyst Switches have identical hardware but
    > different IOS ?


    yes

    > * If I upgrade the SMI to EMI do I then have a device identical (in
    > software & hardware) to an original Catalyst 3550-24-EMI ?


    yes

    m.
     
    Marcin Strzyzewski, Oct 18, 2003
    #2
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  3. JohnNews

    Steinar Haug Guest

    [Marcin Strzyzewski]

    | > * What are the main differences between 3550-24-SMI and 3550-24-EMI ?
    |
    | The EMI enables a richer set of enterprise-class features, including
    | hardware-based IP Unicast routing

    No, SMI does hardware based IP unicast routing just fine, including
    static routes and (as far as I remember) RIPv2. Required a reasonably
    new IOS version (to have this in SMI).

    Steinar Haug, Nethelp consulting,
     
    Steinar Haug, Oct 18, 2003
    #3
  4. Also, SMI cannot do dot1q on routed ports. This is important if you wanted
    to use a 3550 to route between VLANs on a trunk from, say, a rack of
    switches. There are means around this (like leave it as a switch port and
    route on a SVI) but be aware of this limitation in SMI.
    Remember that EMI AND SMI can only route IP. They cannot route
    IPX/Apple/DEC.

    OSB


    "Steinar Haug" <> wrote in message
    news:...
    > [Marcin Strzyzewski]
    >
    > | > * What are the main differences between 3550-24-SMI and

    3550-24-EMI ?
    > |
    > | The EMI enables a richer set of enterprise-class features, including
    > | hardware-based IP Unicast routing
    >
    > No, SMI does hardware based IP unicast routing just fine, including
    > static routes and (as far as I remember) RIPv2. Required a reasonably
    > new IOS version (to have this in SMI).
    >
    > Steinar Haug, Nethelp consulting,
     
    One Step Beyond, Oct 18, 2003
    #4
  5. JohnNews

    Steinar Haug Guest

    ["One Step Beyond"]

    | Also, SMI cannot do dot1q on routed ports. This is important if you wanted
    | to use a 3550 to route between VLANs on a trunk from, say, a rack of
    | switches.

    Can the EMI version do this? Maybe you can post a configuration example.

    Steinar Haug, Nethelp consulting,
     
    Steinar Haug, Oct 18, 2003
    #5
  6. JohnNews

    Jason Kau Guest

    Steinar Haug <> wrote:
    > ["One Step Beyond"]
    >
    > | Also, SMI cannot do dot1q on routed ports. This is important if you wanted
    > | to use a 3550 to route between VLANs on a trunk from, say, a rack of
    > | switches.
    >
    > Can the EMI version do this? Maybe you can post a configuration example.


    Why would you want to do dot1q on routed interfaces when you can do routing on
    SVI interfaces? That is, you setup your physical interface as a trunk port
    and then you setup SVI interfaces (i.e. "interface vlan <number>") with the
    layer 3 routing and route among the SVI interfaces.

    --
    Jason Kau
    http://www.cnd.gatech.edu/~jkau
     
    Jason Kau, Oct 18, 2003
    #6
  7. JohnNews

    Steinar Haug Guest

    [Jason Kau]

    | > | Also, SMI cannot do dot1q on routed ports. This is important if you wanted
    | > | to use a 3550 to route between VLANs on a trunk from, say, a rack of
    | > | switches.
    | >
    | > Can the EMI version do this? Maybe you can post a configuration example.
    |
    | Why would you want to do dot1q on routed interfaces when you can do routing on
    | SVI interfaces? That is, you setup your physical interface as a trunk port
    | and then you setup SVI interfaces (i.e. "interface vlan <number>") with the
    | layer 3 routing and route among the SVI interfaces.

    Sure, that is the "normal" way of doing it. If, however, you have VLAN
    trunks with overlapping VLAN ranges, you cannot use SVIs. Subinterfaces
    directly on the ports would be able to handle this, but I don't believe
    the 3550 can do subinterfaces directly on the ports. 6500/7600 with
    GE-WAN OSM can do it, and the good old 2948G-L3 can do it.

    Steinar Haug, Nethelp consulting,
     
    Steinar Haug, Oct 18, 2003
    #7
  8. 3550 can do subinterfaces on the routed ports. Even SMI can do this and
    sure you can use secondary addresses on those subinterfaces with SMI.
    However, you CANNOT do dot1q encapsulation on a routed port on the SMI
    image. You need to use the EMI image to do that. As I said earlier, you'd
    want to do this if you had a stack of purely layer 2 swicthes and wanted a
    port to act as a trunk connected to one of the 3550 routed ports. You
    cannot do this by router on a stick with the SMI image since it does not
    support dot1q on routed ports.

    OSB


    "Steinar Haug" <> wrote in message
    news:...
    > [Jason Kau]
    >
    > | > | Also, SMI cannot do dot1q on routed ports. This is important if

    you wanted
    > | > | to use a 3550 to route between VLANs on a trunk from, say, a rack

    of
    > | > | switches.
    > | >
    > | > Can the EMI version do this? Maybe you can post a configuration

    example.
    > |
    > | Why would you want to do dot1q on routed interfaces when you can do

    routing on
    > | SVI interfaces? That is, you setup your physical interface as a trunk

    port
    > | and then you setup SVI interfaces (i.e. "interface vlan <number>") with

    the
    > | layer 3 routing and route among the SVI interfaces.
    >
    > Sure, that is the "normal" way of doing it. If, however, you have VLAN
    > trunks with overlapping VLAN ranges, you cannot use SVIs. Subinterfaces
    > directly on the ports would be able to handle this, but I don't believe
    > the 3550 can do subinterfaces directly on the ports. 6500/7600 with
    > GE-WAN OSM can do it, and the good old 2948G-L3 can do it.
    >
    > Steinar Haug, Nethelp consulting,
     
    One Step Beyond, Oct 19, 2003
    #8
  9. JohnNews

    Steinar Haug Guest

    ["One Step Beyond"]

    | 3550 can do subinterfaces on the routed ports. Even SMI can do this and
    | sure you can use secondary addresses on those subinterfaces with SMI.
    | However, you CANNOT do dot1q encapsulation on a routed port on the SMI
    | image. You need to use the EMI image to do that.

    I'm willing to believe 3550-EMI and dot1q encapsulation on a routed port
    if you can show me a working example - not otherwise. I can't find anything
    in the documentation which indicates this is possible.

    Steinar Haug, Nethelp consulting,
     
    Steinar Haug, Oct 19, 2003
    #9
  10. JohnNews

    Blaz Zupan Guest

    In article <bmtv9c$qlavb$-berlin.de>, One Step Beyond wrote:
    > 3550 can do subinterfaces on the routed ports. Even SMI can do this and
    > sure you can use secondary addresses on those subinterfaces with SMI.
    > However, you CANNOT do dot1q encapsulation on a routed port on the SMI
    > image. You need to use the EMI image to do that. As I said earlier, you'd
    > want to do this if you had a stack of purely layer 2 swicthes and wanted a
    > port to act as a trunk connected to one of the 3550 routed ports. You
    > cannot do this by router on a stick with the SMI image since it does not
    > support dot1q on routed ports.


    Not sure where you buy you 3550 EMI, but the ones I bought don't support dot1q
    encapsulation on routed ports:

    interface FastEthernet0/23
    no switchport
    no ip address
    shutdown
    end

    switch-mb4#conf t
    Enter configuration commands, one per line. End with CNTL/Z.
    switch-mb4(config)#int f0/23.1
    switch-mb4(config-subif)#encapsulation dot1q 10
    ^
    % Invalid input detected at '^' marker.

    switch-mb4(config-subif)#

    It's running this IOS:

    IOS (tm) C3550 Software (C3550-I5Q3L2-M), Version 12.1(13)EA1c,
    RELEASE SOFTWARE (fc1)
     
    Blaz Zupan, Oct 19, 2003
    #10
  11. Take my word for it.

    "Steinar Haug" <> wrote in message
    news:...
    > ["One Step Beyond"]
    >
    > | 3550 can do subinterfaces on the routed ports. Even SMI can do this

    and
    > | sure you can use secondary addresses on those subinterfaces with SMI.
    > | However, you CANNOT do dot1q encapsulation on a routed port on the SMI
    > | image. You need to use the EMI image to do that.
    >
    > I'm willing to believe 3550-EMI and dot1q encapsulation on a routed port
    > if you can show me a working example - not otherwise. I can't find

    anything
    > in the documentation which indicates this is possible.
    >
    > Steinar Haug, Nethelp consulting,
     
    One Step Beyond, Oct 20, 2003
    #11
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