Few Basic questions VLAN and OSPF

satishtechsatishtech Member Posts: 243
1.Can a VLAN Interface have a secondary IP assigned to it ?

2.How many DR/BDR in a Network ? I see multiple DR's even
when one of the DR int IP is lesser than the other.


  • networker050184networker050184 Mod Posts: 11,962 Mod
    1. For the most part yes. Always check your exact model/software version for things like this though.

    2. As many multi access links you have in your network.
    An expert is a man who has made all the mistakes which can be made.
  • SimridSimrid Member Posts: 327
    Adding on to the above post - you maybe left in a scenario where you have a network attached to vlan 10 and you have ran out of hosts, you could add a secondary IP of as a tempoary fix to allow for the network expansion.
    Network Engineer | London, UK | Currently working on: CCIE Routing & Switching

  • satishtechsatishtech Member Posts: 243
    Packet Tracer does not have the secondary command .

    Is the OSPF multicast address ALLDRouters ( which is used
    when DROTHERS want to send information to DR's ) also used
    for communication between DR's and BDR's ?

    Do I need to know how to configure dynamic,reflexive and time-based
    ACL's for the ccent ? saw the theory in flash cards 100-101 book.

    Thank You All.
  • pinkiaiiipinkiaiii Member Posts: 216
    just finished chapter on ospf-the reason for seeing multiple dr bdr routers is because of area 0,
    thus in small network called single area-where there might be one or two routers-there would be 1DR 1BDR or just DR on stub network with single router.
    thus area 0 when entering command network x.x.x.x wildcard mask area-0 can serve as your middle point to other large networks,thus isolating any u'needed messages flooding if in other network one of routers went down.Thus no flooding of unnecessary calculations to run all over networks for other routers-since edge router would only need to know another path to location.In other words its just separating networks of multicast messages from preventing congestion on bandwidth from all messages,if there would be more then say 6-8 routers and one went down.

    not sure about applying second ip on vlan,what sort of command would be used,since routers can support multiple interfaces for encapsulation on single port,not sure do switches have same function supporting several virtual interfaces on single port.

    ccent covers only single area ospf,also think theres two multicast ips and,and ACLs should be basic as either standard or extended permit or deny networks or services,none of the above you mentioned,those would be for ccnp,more likely.Dont take my word for it thou since learning and just finishing semester 2,which is basically equal to prepare for ccent-but topics covered were just on basic acls,and as said only single area ospf is covered in semester 2.
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