Migration OSPF -> EIGRP

Discussion in 'Cisco' started by dennis, Dec 7, 2007.

  1. dennis

    dennis Guest

    Hi group,

    for a customer I should plan the migration from ospf -> eigrp
    What is the best practice..
    Should I run on all the routers/switches two protocols (eigrp and
    ospf) and should I also do a mutual redistribution ?

    And on the last step I would remove the ospf process with no router
    ospf 1 !? Then there should all the routes learnd via eigrp !?

    thx for you comments....

    dennis
     
    dennis, Dec 7, 2007
    #1
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  2. dennis

    Trendkill Guest

    On Dec 7, 2:10 am, dennis <> wrote:
    > Hi group,
    >
    > for a customer I should plan the migration from ospf -> eigrp
    > What is the best practice..
    > Should I run on all the routers/switches two protocols (eigrp and
    > ospf) and should I also do a mutual redistribution ?
    >
    > And on the last step I would remove the ospf process with no router
    > ospf 1 !? Then there should all the routes learnd via eigrp !?
    >
    > thx for you comments....
    >
    > dennis


    Turn up both, do not redistribute (since it will not be there post
    migration), but do redistribute from other sources if you do it today
    via ospf (ie, statics, bgp, etc). Then check routing tables as eigrp
    should be preferred out of the getgo due to the lower administrative
    distance (internal eigrp at least). Lastly, you can rip out ospf one
    at a time, but I would save the config first, then do a 'reload in 10'
    command, and that way if a remote router drops after you remove ospf,
    then it will bounce in 10 minutes to the saved config and come back
    up. Do the rip-out slow and steady, and make sure each device stays
    up as expected before moving on...
     
    Trendkill, Dec 7, 2007
    #2
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  3. dennis

    Merv Guest

    > for a customer I should plan the migration from ospf -> eigrp

    Why does the sustomer want to do this migration ?

    How many routers does the client have that need to be migrated ?
     
    Merv, Dec 7, 2007
    #3
  4. dennis

    dennis Guest

    On 7 Dez., 13:07, Merv <> wrote:
    > > for a customer I should plan the migration from ospf -> eigrp

    >
    > Why does the sustomer want to do this migration ?

    There is a policy from customers big company...also there is a plain
    cisco environment


    >
    > How many routers does the client have that need to be migrated ?


    maybe about 25
     
    dennis, Dec 7, 2007
    #4
  5. dennis

    dennis Guest

    On 7 Dez., 12:02, Trendkill <> wrote:
    > On Dec 7, 2:10 am, dennis <> wrote:
    >
    > > Hi group,

    >
    > > for a customer I should plan the migration from ospf -> eigrp
    > > What is the best practice..
    > > Should I run on all the routers/switches two protocols (eigrp and
    > > ospf) and should I also do a mutual redistribution ?

    >
    > > And on the last step I would remove the ospf process with no router
    > > ospf 1 !? Then there should all the routes learnd via eigrp !?

    >
    > > thx for you comments....

    >
    > > dennis

    >
    > Turn up both, do not redistribute (since it will not be there post
    > migration), but do redistribute from other sources if you do it today
    > via ospf (ie, statics, bgp, etc). Then check routing tables as eigrp
    > should be preferred out of the getgo due to the lower administrative
    > distance (internal eigrp at least). Lastly, you can rip out ospf one
    > at a time, but I would save the config first, then do a 'reload in 10'
    > command, and that way if a remote router drops after you remove ospf,
    > then it will bounce in 10 minutes to the saved config and come back
    > up. Do the rip-out slow and steady, and make sure each device stays
    > up as expected before moving on...



    thanks a lot for the detailed informations...
    There are several staticroutes in the ospf process redistributed which
    have an admin distance of 110. Then I redistribute the static without
    an metric command into eigrp the admin distance is 170....from this
    point...the static routes are only learnded from ospf while better
    admin distance....what do you think...when I change the admin
    distances from eigrp internal 90 and external to 100...all the static
    routes are now learned from eigrp ...end the network interuppt is
    really short...

    dennis
     
    dennis, Dec 7, 2007
    #5
  6. dennis

    Thrill5 Guest

    Ben there, done that. I would not recommend running both protocols even
    without redistribution because the routing tables get all screwed up because
    OSPF and EIGRP use different metrics. We bought another company that was
    running OSPF, and we were running EIGRP. The decision was made to go with
    EIGRP. Our plan was to add EIGRP one weekend and then remove OSPF the next.
    We ran into big problems and ended up removing OSPF the same night. We did
    NOT redistribute any routes but we ran into a problem where routes were
    getting redistributed! It seems that even though you don't have
    redistribution turned on. If you have a route being learned via EIGRP and
    OSPF, and the OSPF route is the better route, then it is the one installed
    into the routing table. Now, since this route was learned via EIGRP, it is
    also advertised via EIGRP. The problem is that the metrics EIGRP uses to
    advertise this route come from the routing table, not from the EIGRP
    topology table, so you in affect you get redistribution without
    redistribution being turned on. This was a number of years ago and I think
    this was only happening on static routes being redistributed into EIGRP. I
    remember this because our default route was being blackholed at various
    locations, when it suppose to be pointing to our core location.


    "Trendkill" <> wrote in message
    news:...
    > On Dec 7, 2:10 am, dennis <> wrote:
    >> Hi group,
    >>
    >> for a customer I should plan the migration from ospf -> eigrp
    >> What is the best practice..
    >> Should I run on all the routers/switches two protocols (eigrp and
    >> ospf) and should I also do a mutual redistribution ?
    >>
    >> And on the last step I would remove the ospf process with no router
    >> ospf 1 !? Then there should all the routes learnd via eigrp !?
    >>
    >> thx for you comments....
    >>
    >> dennis

    >
    > Turn up both, do not redistribute (since it will not be there post
    > migration), but do redistribute from other sources if you do it today
    > via ospf (ie, statics, bgp, etc). Then check routing tables as eigrp
    > should be preferred out of the getgo due to the lower administrative
    > distance (internal eigrp at least). Lastly, you can rip out ospf one
    > at a time, but I would save the config first, then do a 'reload in 10'
    > command, and that way if a remote router drops after you remove ospf,
    > then it will bounce in 10 minutes to the saved config and come back
    > up. Do the rip-out slow and steady, and make sure each device stays
    > up as expected before moving on...
     
    Thrill5, Dec 8, 2007
    #6
  7. dennis

    stephen Guest

    --
    Regards

    - replace xyz with ntl
    "dennis" <> wrote in message
    news:...
    > Hi group,
    >
    > for a customer I should plan the migration from ospf -> eigrp
    > What is the best practice..
    > Should I run on all the routers/switches two protocols (eigrp and
    > ospf) and should I also do a mutual redistribution ?
    >
    > And on the last step I would remove the ospf process with no router
    > ospf 1 !? Then there should all the routes learnd via eigrp !?


    a tutorial on 1 way to migrate between protocols:
    http://www.nil.com/ipcorner/ChangingRoutingProtocol/

    the warnings on the 1st page are the important bit :)

    Note - this looks like a good painless method, but i havent tried this in
    anger (although it looks like i may have to in the next few months).

    Also - this is for moving from EIGRP to OSPF, not the other way around (and
    personally i would much rather have OSPF in place thasn EIGRP - it seems
    much more predictable and reliable).

    i have it done this change, and other vairations such as RIP to OSPF other
    ways as well, where you configure the new protocol in the centre of the
    network, redistribute, and then move the border out towards the edge of the
    network.

    that one i really dont recommend as it is much more disruptive, and much
    more awkward if you have a resilient network with multiple paths to a
    site......
    >
    > thx for you comments....
    >
    > dennis
     
    stephen, Dec 8, 2007
    #7
  8. dennis

    Guest

    On 8 Dis, 18:25, "stephen" <> wrote:
    > --
    > Regards
    >
    > - replace xyz with ntl"dennis" <> wrote in message
    >
    > news:...
    >
    > > Hi group,

    >
    > > for a customer I should plan the migration from ospf -> eigrp
    > > What is the best practice..
    > > Should I run on all the routers/switches two protocols (eigrp and
    > > ospf) and should I also do a mutual redistribution ?

    >
    > > And on the last step I would remove the ospf process with no router
    > > ospf 1 !? Then there should all the routes learnd via eigrp !?

    >
    > a tutorial on 1 way to migrate between protocols:http://www.nil.com/ipcorner/ChangingRoutingProtocol/
    >
    > the warnings on the 1st page are the important bit :)
    >
    > Note - this looks like a good painless method, but i havent tried this in
    > anger (although it looks like i may have to in the next few months).
    >
    > Also - this is for moving from EIGRP to OSPF, not the other way around (and
    > personally i would much rather have OSPF in place thasn EIGRP - it seems
    > much more predictable and reliable).
    >
    > i have it done this change, and other vairations such as RIP to OSPF other
    > ways as well, where you configure the new protocol in the centre of the
    > network, redistribute, and then move the border out towards the edge of the
    > network.
    >
    > that one i really dont recommend as it is much more disruptive, and much
    > more awkward if you have a resilient network with multiple paths to a
    > site......
    >
    >
    >
    >
    >
    > > thx for you comments....

    >
    > > dennis- Itago ang tekstong may panipi -

    >
    > -Ipakita ang tekstong may panipi-



    how about if you use the "distance" command? an option would be to add
    the new protocol without removing the old one but since the default
    admin distance of eigrp is lower than ospf (90, 110), once u add in
    eigrp those routes will be preffred, unless you lower the admin
    distance of ospf (lower than 90) until you are ready to convert to
    eigrp.

    ex

    router eigrp 1
    network 172.16.0.0

    router ospf 1
    network 172.16.0.0
    distance 70

    once the eigrp process is added, ospf will still be preferred and when
    u are ready to go to eigrp, just change the distance of ospf back to
    the default distance of 110, then the ospf routes will age out and
    voila! your eigrp routes are now preferred. (or u can force it via
    clear ip route *), if something goes wrong, u can back out easily by
    returning the distance command under ospf to 70 so the ospf routes
    will be preferrd. once everything is working and stable, u can remove
    the ospf process on all the routers without further distruptions

    hope this helps!
     
    , Dec 8, 2007
    #8
  9. dennis

    Thrill5 Guest

    "stephen" <> wrote in message
    news:siu6j.7999$...
    >
    >
    > --
    > Regards
    >
    > - replace xyz with ntl
    > "dennis" <> wrote in message
    > news:...
    >> Hi group,
    >>
    >> for a customer I should plan the migration from ospf -> eigrp
    >> What is the best practice..
    >> Should I run on all the routers/switches two protocols (eigrp and
    >> ospf) and should I also do a mutual redistribution ?
    >>
    >> And on the last step I would remove the ospf process with no router
    >> ospf 1 !? Then there should all the routes learnd via eigrp !?

    >
    > a tutorial on 1 way to migrate between protocols:
    > http://www.nil.com/ipcorner/ChangingRoutingProtocol/
    >
    > the warnings on the 1st page are the important bit :)
    >
    > Note - this looks like a good painless method, but i havent tried this in
    > anger (although it looks like i may have to in the next few months).
    >
    > Also - this is for moving from EIGRP to OSPF, not the other way around
    > (and
    > personally i would much rather have OSPF in place thasn EIGRP - it seems
    > much more predictable and reliable).
    >
    > i have it done this change, and other vairations such as RIP to OSPF other
    > ways as well, where you configure the new protocol in the centre of the
    > network, redistribute, and then move the border out towards the edge of
    > the
    > network.
    >
    > that one i really dont recommend as it is much more disruptive, and much
    > more awkward if you have a resilient network with multiple paths to a
    > site......
    >>
    >> thx for you comments....
    >>
    >> dennis

    >
    >

    I have worked with both OSPF and EIGRP in very large networks (more that
    1000 routers), and EIGRP is just as predictable and reliable as OSPF, but by
    far it is much easier to manage. There is a reason that Cisco has never
    submitted EIGRP to standards bodies for adoption as a standard routing
    protocol, and why most enterprises run EIGRP (unofficially, according to
    Cisco it is over 80%.)
     
    Thrill5, Dec 9, 2007
    #9
  10. dennis

    dennis Guest

    Steven,

    your recommendation is really good. I think that would be work
    perfectly...with maybe a small exception....so I would like to change
    the dead interval under ospf to minimimal with "ip ospf dead-
    interval .
    So when I remove the ospf process there should be only a short
    interrupt while changing the routing tables from ospf to eigrp
    routes..

    dennis
    > how about if you use the "distance" command? an option would be to add
    > the new protocol without removing the old one but since the default
    > admin distance of eigrp is lower than ospf (90, 110), once u add in
    > eigrp those routes will be preffred, unless you lower the admin
    > distance of ospf (lower than 90) until you are ready to convert to
    > eigrp.
    >
    > ex
    >
    > router eigrp 1
    > network 172.16.0.0
    >
    > router ospf 1
    > network 172.16.0.0
    > distance 70
    >
    > once the eigrp process is added, ospf will still be preferred and when
    > u are ready to go to eigrp, just change the distance of ospf back to
    > the default distance of 110, then the ospf routes will age out and
    > voila! your eigrp routes are now preferred. (or u can force it via
    > clear ip route *), if something goes wrong, u can back out easily by
    > returning the distance command under ospf to 70 so the ospf routes
    > will be preferrd. once everything is working and stable, u can remove
    > the ospf process on all the routers without further distruptions
    >
    > hope this helps!
     
    dennis, Dec 9, 2007
    #10
  11. dennis

    Merv Guest

    Why dont' you just get a 4 hour maintenance window and just replace
    the OSPF routing process with EIGRP in one go

    You indicated that there are only 25 routers; if there were hundreds
    of routers it would be a different matter

    You can always telnet from one router to the next immediate router via
    the shared connected route.

    Also remember to enable EIGRP stub routing feature on any spoke
    routers to reduce queries
     
    Merv, Dec 9, 2007
    #11
  12. dennis

    Merv Guest

    OBTW have you done an IOS version inventory and then done an EIGRP bug
    scrub
    for those versions to ensure you are not going to step on known EIGRP
    defects ?

    Also to ensure that none of the IOS versions in use have been yanked
    ("deferred") by Cisco ?
     
    Merv, Dec 9, 2007
    #12
  13. dennis

    stephen Guest

    "Thrill5" <> wrote in message
    news:...
    >
    > "stephen" <> wrote in message
    > news:siu6j.7999$...
    > >
    > >
    > > --
    > > Regards
    > >
    > > - replace xyz with ntl
    > > "dennis" <> wrote in message
    > >

    news:...
    > >> Hi group,
    > >>
    > >> for a customer I should plan the migration from ospf -> eigrp
    > >> What is the best practice..
    > >> Should I run on all the routers/switches two protocols (eigrp and
    > >> ospf) and should I also do a mutual redistribution ?
    > >>
    > >> And on the last step I would remove the ospf process with no router
    > >> ospf 1 !? Then there should all the routes learnd via eigrp !?

    > >
    > > a tutorial on 1 way to migrate between protocols:
    > > http://www.nil.com/ipcorner/ChangingRoutingProtocol/
    > >
    > > the warnings on the 1st page are the important bit :)
    > >
    > > Note - this looks like a good painless method, but i havent tried this

    in
    > > anger (although it looks like i may have to in the next few months).
    > >
    > > Also - this is for moving from EIGRP to OSPF, not the other way around
    > > (and
    > > personally i would much rather have OSPF in place thasn EIGRP - it seems
    > > much more predictable and reliable).
    > >
    > > i have it done this change, and other vairations such as RIP to OSPF

    other
    > > ways as well, where you configure the new protocol in the centre of the
    > > network, redistribute, and then move the border out towards the edge of
    > > the
    > > network.
    > >
    > > that one i really dont recommend as it is much more disruptive, and much
    > > more awkward if you have a resilient network with multiple paths to a
    > > site......
    > >>
    > >> thx for you comments....
    > >>
    > >> dennis

    > >
    > >

    > I have worked with both OSPF and EIGRP in very large networks (more that
    > 1000 routers), and EIGRP is just as predictable and reliable as OSPF, but

    by
    > far it is much easier to manage. There is a reason that Cisco has never
    > submitted EIGRP to standards bodies for adoption as a standard routing
    > protocol, and why most enterprises run EIGRP (unofficially, according to
    > Cisco it is over 80%.)


    there are some good arguments for EIGRP, and it is easy to turn on and get
    working.

    my experience has been that it is much easier for changes in EIGRP to leave
    you with something that mainly works, but has problems with scale.
    OSPF has some pretty "hard" built in rules about structure that mean it
    needs clean design - but that isnt a disadvantage when you see what
    unconstrained growth can do to EIGRP.

    the killer negative ones are when you need to integrate with other
    manufacturers (or even some of the niche Cisco gear that doesnt speak
    EIGRP).

    my 1st intro to EIGRP problems was adding VPN 3000s to an existing EIGRP
    system (they only spoke OSPF / RIP at the time). The 1st one was trivial,
    but several with resilience and failover was painful.

    A big current network i work on has Foundry L3 switches everywhere as well
    as Cisco.
    OSPF, or BGP were the choices, but only OSPF would give the failover times
    we needed.

    And the latest at work was adding the control system for a DWDM long haul
    OADM deployment.
    it provides a 100 Mbps "telemetry" network as a side effect which is really
    useful - but the existing control net is EIGRP, and sprawls across 500 sites
    with dual feeds everywhere.
    Integrating the 2 was a major problem, which would have been much more
    controllable with existing routing on OSPF (or even BGP).
    >

    --
    Regards

    - replace xyz with ntl
     
    stephen, Dec 9, 2007
    #13
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