ip helper / dhcp / source address
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Posted by GT on May 29, 2008, 10:04 am
Please log in for more thread options packet that is generated by a router configured with 'ip helper A.B.C.D' on a local interface would be. i need to know this as the router is connected via an IPSEC VPN (crypto enabled on the dialer0 interface) to a central location on which the DHCP server is connected, and i need to be sure that the forwarded dhcp request will generate crytpo. Thanks | |||||||||||||
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Posted by Trendkill on May 29, 2008, 10:09 am
Please log in for more thread options It should be the IP of the SVI that received the DHCP request. To put it more clearly, if a node broadcasts a request for an IP, whatever router interface received that broadcast will be used as the source IP of the request so that the DHCP server knows which subnet to give an IP from. That is my understanding, but have never really sniffed the dhcp server side of the request. | |||||||||||||
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Posted by GT on May 29, 2008, 10:49 am
Please log in for more thread options >
> > Dear all, i just wanted to check what the source address of the IP
> > packet that is generated by a router configured with 'ip helper > > A.B.C.D' on a local interface would be. >
> > i need to know this as the router is connected via an IPSEC VPN
> > (crypto enabled on the dialer0 interface) to a central location on > > which the DHCP server is connected, and i need to be sure that the > > forwarded dhcp request will generate crytpo. >
> > Thanks
>
> It should be the IP of the SVI that received the DHCP request. =A0To put > it more clearly, if a node broadcasts a request for an IP, whatever > router interface received that broadcast will be used as the source IP > of the request so that the DHCP server knows which subnet to give an > IP from. =A0That is my understanding, but have never really sniffed the > dhcp server side of the request. Thanks for post reply. one (poss dum qu !) - what does SVI stand for ? | |||||||||||||
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Posted by Trendkill on May 29, 2008, 10:52 am
Please log in for more thread options >
> > > > > > Dear all, i just wanted to check what the source address of the IP
> > > packet that is generated by a router configured with 'ip helper > > > A.B.C.D' on a local interface would be. >
> > > i need to know this as the router is connected via an IPSEC VPN
> > > (crypto enabled on the dialer0 interface) to a central location on > > > which the DHCP server is connected, and i need to be sure that the > > > forwarded dhcp request will generate crytpo. >
> > > Thanks
>
> > It should be the IP of the SVI that received the DHCP request. To put
> > it more clearly, if a node broadcasts a request for an IP, whatever > > router interface received that broadcast will be used as the source IP > > of the request so that the DHCP server knows which subnet to give an > > IP from. That is my understanding, but have never really sniffed the > > dhcp server side of the request. >
> Thanks for post reply. > > one (poss dum qu !) - what does SVI stand for ? Switched virtual interface. If you are running a layer 3 switch or layer 2 with MSFC, its the vlan interface. Its basically the layer 3 interface in a network that generally acts as an entry/exit point to the subnet/vlan. If you are running a router on a stick (router to a switch), then the f0/1 or g0/1 would be the SVI, although in this situation its usually just referred to as an interface. | |||||||||||||
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Posted by Merv on May 29, 2008, 12:11 pm
Please log in for more thread options >
> > > > > > > > Dear all, i just wanted to check what the source address of the IP
> > > > packet that is generated by a router configured with 'ip helper > > > > A.B.C.D' on a local interface would be. >
> > > > i need to know this as the router is connected via an IPSEC VPN
> > > > (crypto enabled on the dialer0 interface) to a central location on > > > > which the DHCP server is connected, and i need to be sure that the > > > > forwarded dhcp request will generate crytpo. >
> > > > Thanks
>
> > > It should be the IP of the SVI that received the DHCP request. To put
> > > it more clearly, if a node broadcasts a request for an IP, whatever > > > router interface received that broadcast will be used as the source IP > > > of the request so that the DHCP server knows which subnet to give an > > > IP from. That is my understanding, but have never really sniffed the > > > dhcp server side of the request. >
> > Thanks for post reply.
>
> > one (poss dum qu !) - what does SVI stand for ?
>
> Switched virtual interface. If you are running a layer 3 switch or > layer 2 with MSFC, its the vlan interface. Its basically the layer 3 > interface in a network that generally acts as an entry/exit point to > the subnet/vlan. If you are running a router on a stick (router to a > switch), then the f0/1 or g0/1 would be the SVI, although in this > situation its usually just referred to as an interface. | |||||||||||||
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> packet that is generated by a router configured with 'ip helper
> A.B.C.D' on a local interface would be.
>
> i need to know this as the router is connected via an IPSEC VPN
> (crypto enabled on the dialer0 interface) to a central location on
> which the DHCP server is connected, and i need to be sure that the
> forwarded dhcp request will generate crytpo.
>
> Thanks