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Home > Archive > CCNP > September 2002 > dhcp forwarding on router
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dhcp forwarding on router
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| niallg 2002-08-29, 3:51 am |
| I have ip helper addresses on an ethernet interface for workstations to retrieve dhcp addresses.
Workstations do not retrieve ip lease from either dhcp server. Scopes & activation all correct as it serves other subnets.
This is happening from 2 remote sites.
IOS 12.2 running ospf
Had a look at the cisco website but read conflicting info re: no ip directed-broadcast on ethernet inrterface ?? | |
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| MadChef 2002-08-30, 5:23 am |
| quote:
Originally posted by niallg
Workstations do not retrieve ip lease from either dhcp server. Scopes & activation all correct as it serves other subnets.
Now how exactly would this scope serve other subnets? I'd revisit that one again if I were you.
quote:
Had a look at the cisco website but read conflicting info re: no ip directed-broadcast on ethernet inrterface
ip directed broadcast doesn't enter into it unless you're forwarding broadcasts to the broadcast address of the subnet housing the dhcp servers.
MadChef | |
| niallg 2002-09-02, 2:14 am |
| More info:
2 w2k dhcp servers 10.1.1.5 & 10.1.40.5 for failover.
All clients on vlans (10.1.1.0/24; 10.1.2.0/24; 10.1.3.0/24...) of routing switch retrieve relevant dhcp configs from either dhcp server via
ip helper-address 10.1.1.5
ip helper-address 10.1.40.5
Problem is with dhcp-enabled clients from a remote site 10.1.20.0 coming in from router 10.1.20.1
Router 10.1.20.1 has 2 ip helper-address statements as above plus
no ip forward-protocol udp tftp, nameserver, domain, time, netbios-ns, netbios-dgm, tacacs | |
| MadChef 2002-09-02, 5:27 am |
| quote:
Originally posted by niallg
Router 10.1.20.1 has 2 ip helper-address statements as above plus
no ip forward-protocol udp tftp, nameserver, domain, time, netbios-ns, netbios-dgm, tacacs
As long as you don't have bootpc the router won't do anything to block those broadcasts. Try sniffing one of the dhcp server segments or debugging ip packets with the appropriate access list applied.
Have you verified connectivity to and from the remote site? Can you ping the DHCP servers with packets sourced from 10.1.20.1? Is the scope activated and does it have the correct gateway set?
MadChef |
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