stupid router question

exampasserexampasser Member Posts: 718 ■■■□□□□□□□
On a Cisco router that I was configuring a serial interface to receive a dynamic IP address from an upstream router I have read that all I need to to is while in interface configuration mode use the command "ip address dhcp" but when I do I'm just getting an invalid input error:

Router(config-if)#ip address dhcp
_______________________^
% Invalid input detected at "^" marker

EDIT:The only thing that I can think of is the possibility that serial interfaces do not support the command.

UPDATE: I tested the command on a spare Ethernet interface, so it appears that I'm right. I was doing a scenario in a lab in which the border router for a network performed NAT and obtained a public IP from the ISP.

Comments

  • MAC_AddyMAC_Addy Member Posts: 1,740 ■■■■□□□□□□
    Did you configure the fa0/0? If not, configure that. Then once that's done, go back to privileged mode. Then type in 'ip dhcp pool ippool_1' ippool_1 being the name of the DHCP group from there you can setup the network addresses.
    2017 Certification Goals:
    CCNP R/S
  • ccnaomkarccnaomkar Member Posts: 187 ■■□□□□□□□□
    use fast ethernet interface for nat translation if u have 2 fast ethernet interfaces

    u can use command
    ip address dhcp

    with u have to provide
    ip domain-lookup
    ip name-server

    in global config mode
  • billyrbillyr Member Posts: 186
    exampasser wrote: »
    On a Cisco router that I was configuring a serial interface to receive a dynamic IP address from an upstream router I have read that all I need to to is while in interface configuration mode use the command "ip address dhcp" but when I do I'm just getting an invalid input error:

    Router(config-if)#ip address dhcp
    _______________________^
    % Invalid input detected at "^" marker

    EDIT:The only thing that I can think of is the possibility that serial interfaces do not support the command.

    UPDATE: I tested the command on a spare Ethernet interface, so it appears that I'm right. I was doing a scenario in a lab in which the border router for a network performed NAT and obtained a public IP from the ISP.



    You are correct, only LAN interfaces support the command.
  • exampasserexampasser Member Posts: 718 ■■■□□□□□□□
    Thanks for the responses guys, I could use an Ethernet interface, it would just require some extra work of setting up vlans as there are no direct Ethernet connections between routers.

    It did dawn on me soon after I shut down the computer last night that it would not make practical sense for a serial interface to support the command as only one device can be hooked up to the other end (unlike Ethernet in which there can be a switch allowing for multiple devices on the other end).
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