Routers....

surfthegeckosurfthegecko Member Posts: 149
Do they have a definable default gateway parameter..... or is this only something that can be defined on a switch?

.....

Also can somebody please simplify (if/where possible) the difference between routed and routing. I think I have it clear in my head, but would like to get a more definitive explanation.

Thanks.

Comments

  • blackninjablackninja Member Posts: 385
    Do they have a definable default gateway parameter..... or is this only something that can be defined on a switch?

    No this is for switches only, to set default gateway for remote management
    Also can somebody please simplify (if/where possible) the difference between routed and routing. I think I have it clear in my head, but would like to get a more definitive explanation.

    A routed protcol is the protocol that it's transported on: IP is the only one used these days

    A routing protocol is the protocol that builds the routing table: RIP, OSPF, EIGRP for example
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  • surfthegeckosurfthegecko Member Posts: 149
    thanks blackninja....much appreciated.

    so if I set the int vlan 1 to: ip address 172.16.16.1 255.255.0.0
    would the switches ip default-gateway just be on the same subnet eg 172.16.16.100 255.255.0.0

    or is this not linked to the vlan interface.
  • amp2030amp2030 Member Posts: 253
    You can set a default route on your router though, of 0.0.0.0 mask 0.0.0.0.
    If it's the only one set up, it will function exactly like a default gateway.
  • amp2030amp2030 Member Posts: 253
    thanks blackninja....much appreciated.

    so if I set the int vlan 1 to: ip address 172.16.16.1 255.255.0.0
    would the switches ip default-gateway just be on the same subnet eg 172.16.16.100 255.255.0.0

    or is this not linked to the vlan interface.

    The vlan ip has to be in the same subnet as the router (which you set as default-gateway) or it will not be able to communicate with it. Note that it does not impact the hosts connecting to ports that are in the same VLAN. It affects strictly your switch (so you can telnet into it, ping it, etc).
  • tndfrtndfr Member Posts: 110
    default gateway in your switch has to be the same subnet as your gateway (i.e. router). just think of your switch like any other PC in your network, if you need to go out of your LAN than you need the default gateway to route you to other LAN segments.

    if you have (a simple internetwork) just one LAN segment and the other segment is the internet separated by a router then you really dont need to set the default
    gateway.
    Working on CCNP 642-813 and finishing off MCSA.
  • surfthegeckosurfthegecko Member Posts: 149
    so just for completeness sake would the following be the correct setup.

    RouterA:
    int vlan1: 172.16.16.1 255.255.0.0

    SwitchA:
    ip default-gateway: 172.16.16.1 255.255.0.0
    int vlan1: 172.16.16.2 255.255.0.0


    Then the fast ethernet between RouterA & SwitchA would be set to what?

    Thanks so far guys, the picture is slowly being painted.
  • amp2030amp2030 Member Posts: 253
    so just for completeness sake would the following be the correct setup.

    RouterA:
    int vlan1: 172.16.16.1 255.255.0.0

    SwitchA:
    ip default-gateway: 172.16.16.1 255.255.0.0
    int vlan1: 172.16.16.2 255.255.0.0


    Then the fast ethernet between RouterA & SwitchA would be set to what?

    Thanks so far guys, the picture is slowly being painted.

    No.

    Your switch setup is correct, but the "fast ethernet" between RouterA and SwitchA has to be set to 172.16.16.1 255.255.0.0, not "vlan1".

    What routers do is direct data traffic between the different subnets that their interfaces connect to. In this simple case, one interface will be on the local subnet (172.16.0.0/16) and one, presumably, will get an ip from the ISP.
  • surfthegeckosurfthegecko Member Posts: 149
    Excellent...thanks for the info. I was being a bit slow and configuring the wrong aspect.

    What should you typically set the int vlan1 ip address to. Would it be something else on that particular subnet or do you pick a completely different subnet all together?


    I have just mapped out the following scenario:
    3 pc's connecting to Switch1 which connects to Router1
    Router1 then connects to Switch2 which connects 3 additional hosts.

    I have managed to get them all pinging each other which has helped to clarify my questions on this post after the knowledge given by you all.

    Thanks for everything guys/gals, once again Techexams forum saves the day icon_smile.gif
  • drew2000drew2000 Member Posts: 290
    What should you typically set the int vlan1 ip address to. Would it be something else on that particular subnet or do you pick a completely different subnet all together?

    Typically you would give the VLAN an IP on that same subnet. What number you give it depends on how your organization allocates IP's. For example, routers could be .1-.5, with switches being .10-.20, printers could be .21-.40, and workstations .50-?.

    Drew
  • surfthegeckosurfthegecko Member Posts: 149
    Thanks Drew....Does it not matter which subnet its on?

    int fa 0/0 is on 192.168.1.1 255.255.255.0
    &
    int fa 0/1 is on 192.168.2.1 255.255.255.0

    which one of the 2 subnets do I setup the vlan on, or does it really not make a difference?
    I tried it on a new subnet of 192.168.3.1 255.255.255.0 and this didnt work.
  • drew2000drew2000 Member Posts: 290
    Surf,
    Your int fa's are on different subnets - I'm losing my grasp on what your objective is.

    I would start out with ONE subnet, with the router and the VLAN both in the same subnet, like this:

    Router IP address: 192.168.1.1 /24

    Switch int vlan 1: ip address 192.168.1.10 /24
    Switch ip default gateway: 192.168.1.1/24

    PC's: 192.168.1.20 - 254 /24

    If you set it up like this, everything should work from a subnet perspective. I know you have multiple switches involved, now those can be on another subnet, with another router interface. Of course, unless you setup a static route or routing protocol it won't work.

    There is a whole additional topic here that I am not addressing because I don't want to muddy the waters, but if you really want to get crazy you can look up layer 3 switches.

    Drew
  • surfthegeckosurfthegecko Member Posts: 149
    Hi Drew,

    I already have the int vlan1 on switch1 & switch2 configured to their subnet range as you described below, but I am now trying to configure the int vlan1 on the router so that it can be remotely managed.

    I can telnet into each of the switches int vlan1 addresses to manage them but dont know how to setup RouterA's int vlan1


    RouterA
    int fa 0/0 192.168.1.1 /24 - SwitchA
    int fa 0/1 192.168.2.1 /24 - SwitchB
    int vlan1 = ?

    SwitchA
    int vlan1 192.168.1.100 /24

    SwitchB
    int vlan1 192.168.2.100 /24


    Hope this makes more sense.
    If im not describing it properly then apologies for this, and maybe dont worry for now, I was just trying to set it up for completeness, its not essential.

    Thanks
  • amp2030amp2030 Member Posts: 253
    I already have the int vlan1 on switch1 & switch2 configured to their subnet range as you described below, but I am now trying to configure the int vlan1 on the router so that it can be remotely managed.

    You don't need to set up a vlan on your router to manage it remotely. You can access it by telnet/ssh to any of its interface IP addresses (in your case 192.168.1.1 or 192.168.2.1).
  • drew2000drew2000 Member Posts: 290
    amp2030 wrote: »
    You don't need to set up a vlan on your router to manage it remotely. You can access it by telnet/ssh to any of its interface IP addresses (in your case 192.168.1.1 or 192.168.2.1).

    Yep x 2 . I'm not even sure that you COULD have a VLAN on a router. I'm sure on some of the high end wicked expensive models you could, but on a common router I don't know why you would need one.

    All you should need to do on the router is setup ethernet 0 (and ethernet 1 if applicable) to an IP on the same subnet as your switch. Then you should be able to telnet from a PC on that same subnet that is connected to a VLAN in that subnet. Should be fine unless there is a previous configuration problem preventing it from working!

    If you are still having trouble, post your config and we'll have a look!

    Drew
  • surfthegeckosurfthegecko Member Posts: 149
    Thanks guys, I never really thought of that.
    Works perfectly on both interfaces.

    I think the reason why I thought it was best to configure int vlan1 was because it actually allowed me to, so thought there must be a specific reason for doing so.

    All working perfectly now.

    Thanks to everybody for their help.
  • phoeneousphoeneous Member Posts: 2,333 ■■■■■■■□□□
    drew2000 wrote: »
    I'm not even sure that you COULD have a VLAN on a router. I'm sure on some of the high end wicked expensive models you could, but on a common router I don't know why you would need one.

    Then how do you expect to route multiple vlan information across several routers? Creating vlan interfaces on a router is beyond the scope of icnd1 but its something you will learn in icnd2. A good example of this use is router-on-a-stick.
  • phoeneousphoeneous Member Posts: 2,333 ■■■■■■■□□□
    Thanks guys, I never really thought of that.
    Works perfectly on both interfaces.

    I think the reason why I thought it was best to configure int vlan1 was because it actually allowed me to, so thought there must be a specific reason for doing so.

    All working perfectly now.

    Thanks to everybody for their help.

    Gecko,

    There is a difference between creating a vlan in the vlan database and creating a vlan interface. Dont get the two mixed up. On a switch, vlans are used to segregate the traffic based on the topology. For example if you have a 24 port switch and you want one subnet to be on ports 1-12 and another subnet to be on ports 13-24. A vlan interface is used to manage the switch remotely. Two different things. More on this stuff in icnd2.
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