DHCP ISSUES

[mirehteshamali]

Hi all,

we are facing some strange DHCP problem in our campus network.

we have installed OS 6850 Switches . problem is when we relocate a user to a different location / new building within our campus , we also shift his pc .

now all pc's are reportedly getting ip address from previous segment .

for example . user bob was connected to 10.1.1.0/24 segment and had a dynmaic ip from a dhcp server . Alcated switch worked as DHCP relay .

when we relocated BOB'S pc to 10.1.100.0/24 segment , bob is still getting ip from previous segment ip 10.1.1.0/24

Multiple users faced same issue we ended up giving static ip . can any one guide me in this issue .

[silvio]

It seems to be a wrong behavior of the dhcp-server.
or you have done wrong design: you never mentioned vlan. Have you separated your network in vlans with the different ip segments -f.e. vlan 1 with 10.1.1.0/24 and vlan 100 with 10.1.100.0/24 ? your gateway need ip interfaces in all networks/vlans. Than ip helper works fine.
regards
Silvio

[mirehteshamali]

thanks Silvo,

we have hirarchical structure comprising of 6850 switches in access layer and 9700 series in distribution and core layer .

we also have seprate vlan for each segment . dhcp relay in configured on distribution switches . clients have their default gateway pointing to distribution layer switches .

. we are upgarding all access layer switches to latest version .

since the issue is not consistant , we firmly suspect its dhcp server service failure some times . this may be due to fact that server is addressing large no of clients nearly 2000 work force .

thanks for inputs