DHCP IP assignment issue - dhcp failover scenario

[Usman Ahmad]

Following is my network overview in which i am facing problem for the IP
assignment. VRRP is configured for the cusomers VLAN passing through the
access node till routers. CPE is sending DHCPDISCOVER to both routers which
they are further forwarding to both DHCP Servers. And the return traffic is
opposite like DHCP Servers --> both routers --> CPE (ACCESS node is working
as layer-2).

        DHCP01(.4)             DHCP02(.5)
 GW:Router-1(.1) GW:Router-2(.2)
            |                                   |
    ------------192.168.2.0/24--------------
    |                                   |
       ----------    ----------
   | Router-1 |   | Router-2 |
   |DHCP-Relay|               |DHCP-Relay|
    --.253------ VRRP(.1)------.254--
    \                                     /
      \   10.30.10.0/24    /
  \                  /
                --------------------
        | ACCES NODE |
    --------------------
                |
               CPE

Please note that IP assignment starts working properly whenever i am
putting router-1 as gateway of DHCP-02 or delete default gateway. But i
dont want to keep both DHCP server replying to one DHCP relay.

On Mon, Dec 17, 2018 at 6:21 PM Abdul Khader <akhader at gmail.com> wrote:

> For troubleshooting take one of the CPE mac address (the CPE which is not
> getting an IP)and check your logs for that mac address if your server is
> responding. Better to take a trace using tcpdump.
> If the server is responding then you need to check if its reaching the
> relays. From relays to CPE.
> Note  there are CPEs which misbehave. Even after getting the ack they send
> discover.
>
> Regards
> Abdul Khader
>
> On Mon, 17 Dec 2018, 17:19 Usman Ahmad <usman.hfd at gmail.com wrote:
>
>> Dear All,
>>
>> I have setup two isc-dhcp-server in fail-over mode and these were working
>> fine since long. Just know i am facing issue that some of my customers CPEs
>> keep sending the  DHCP request and doesn't get the IP however from DHCP
>> logs, i can see the complete DORA process.
>>
>> Please note that both DHCP servers are connected to different Gateway
>> Routers/DHCP relay servers. Since the same DHCP requests are coming from
>> both relay agent so the both DHCP servers are replying to both relay
>> agents.
>>
>> i have isc-dhcp-server v 4.3.1-6 and following is configuration for one
>> server.
>>
>> ddns-update-style none;
>>
>> DHCPDARGS="eth0 eth1";
>>
>> option domain-name-servers xx.xx.xx.xx, yy.yy.yy.yy;
>>
>> default-lease-time 86400;
>> max-lease-time 86400;
>>
>> authoritative;
>>
>> log-facility local7;
>>
>> deny unknown-clients;
>>
>> one-lease-per-client true;
>>
>> failover peer "awasr-dhcp-partner" {
>>          primary;
>>          address 192.168.2.4;
>>          port 519;
>>          peer address 192.168.2.5;
>>          peer port 520;
>>          max-response-delay 60;
>>          max-unacked-updates 10;
>>          mclt 600;
>>          split 128;
>>          load balance max seconds 3;
>> }
>> omapi-port 7911;
>> omapi-key awasr_omapi_key;
>> key awasr_omapi_key {
>>                algorithm hmac-md5;
>>                secret "0asdASCjaeEasWDSAkasjdo/s890amsdASDASfdjka+1DM50=";
>> }
>>
>> include "/etc/dhcp/vlans/customer-vlans.conf";
>>
>>
>> # Sample configuration for a single subnect
>>
>> shared-network 1230 {
>>
>>         option dhcp-parameter-request-list 60,43,3,6,15;
>>         option vendor-class-identifier "dslforum.org";
>>         vendor-option-space UMPSYS;
>>         option UMPSYS.acs-url "http://ump.awasr.com:10301/acs";
>>         option domain-name "awasr.com";
>>
>> subnet 10.32.32.0 netmask 255.255.255.0 {
>>         option routers 10.32.32.1;
>>         pool {
>>             failover peer "awasr-dhcp-partner";
>>             range 10.32.32.25 10.32.32.252;
>>         }
>>      }
>> # for static hosts
>> include "/etc/dhcp/vlans/1230-hosts.conf";
>> }
>>
>> *--*
>> *Regards,*
>> Usman Ahmad
>> _______________________________________________
>> dhcp-users mailing list
>> dhcp-users at lists.isc.org
>> https://lists.isc.org/mailman/listinfo/dhcp-users
>>
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-- 
*--*
*Regards,*
Usman Ahmad
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