IP Helper-address & ICMP port unreachable
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Posted by traust on July 27, 2006, 11:17 am
Please log in for more thread options I am confguring a 6500 with IP helper-address.. done it before on 5500's thousands of times.. no bother.. except this 6500 is sending an ICMP port unreachable to my DHCP server on the Offer!!!?? Why? I thought if it caches the helper bootp request it should recognise the offer coming back!? It is some funky ARP inspection thing (I switched it all off).. Its a base config with secondaries on both interfaces (Vlan 2 & Vlan 3) and a helper address... thats it! Any ideas?! | ||||||||||||||||
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Posted by Martin Bilgrav on July 27, 2006, 2:42 pm
Please log in for more thread options do you run proxy ARP ? Does all your SVI's have the ip helper command ? (Interface Vlan 1, Interface vlan 2 etc) Are there any ACL's ? > I thought if it caches the helper bootp request it should recognise the
> offer coming back!? > > It is some funky ARP inspection thing (I switched it all off).. > > Its a base config with secondaries on both interfaces (Vlan 2 & Vlan 3) > and a helper address... thats it! Can you drop the config snip-let ? Do you mean standby=secondaries or IP ? HTH Martin >
> > Any ideas?! > | ||||||||||||||||
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Posted by traust on July 28, 2006, 5:28 am
Please log in for more thread options Hi.. Yes secondaries.. many of them...
I have come a lot further.. I notice that the relay helper is pushing the requests forward with Src and St prt set at 67 but my server is replying back on 68... hence the port unreachable.. But it still leaves me the quetion that in the field is this still going to be a problem... will I have to PAT the replies in these instances.. does anyone know a good DHCP server that reponds correctly?! Found this excellent link.. http://www.cisco.com/en/US/tech/tk648/tk361/technologies_tech_note09186a00800f0804.shtml but it still doesnt tell you the solution.. | ||||||||||||||||
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Posted by Martin Bilgrav on July 29, 2006, 3:45 pm
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> Hi.. Yes secondaries.. many of them...
Well, some DHCP servers will respond on udp/67 with reply on udp/67 or
> > I have come a lot further.. I notice that the relay helper is pushing > the requests forward with Src and St prt set at 67 but my server is > replying back on 68... hence the port unreachable.. > udp/68 It is a setup/config problem at your DHCP server. > But it still leaves me the quetion that in the field is this still
http://www.cisco.com/en/US/tech/tk648/tk361/technologies_tech_note09186a00800f0804.shtml
> going to be a problem... will I have to PAT the replies in these > instances.. does anyone know a good DHCP server that reponds > correctly?! > > Found this excellent link.. > >
> but it still doesnt tell you the solution.. > | ||||||||||||||||
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Posted by Martin Bilgrav on July 29, 2006, 3:50 pm
Please log in for more thread options
> Hi.. Yes secondaries.. many of them...
Are you, by any chance, setting an IP helper on an interface that is in the
> > I have come a lot further.. I notice that the relay helper is pushing > the requests forward with Src and St prt set at 67 but my server is > replying back on 68... hence the port unreachable.. > same subnet as the DHCP server ? > But it still leaves me the quetion that in the field is this still
http://www.cisco.com/en/US/tech/tk648/tk361/technologies_tech_note09186a00800f0804.shtml
> going to be a problem... will I have to PAT the replies in these > instances.. does anyone know a good DHCP server that reponds > correctly?! > > Found this excellent link.. > >
> but it still doesnt tell you the solution.. > | ||||||||||||||||
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>
> I am confguring a 6500 with IP helper-address.. done it before on
> 5500's thousands of times.. no bother.. except this 6500 is sending an
> ICMP port unreachable to my DHCP server on the Offer!!!??
>
> Why?
>