Re: Cisco DHCP Server Support for MPLS VPNs??

you'll need an IOS image tht supports DHCP Relay Server ID Override
and Link Selection Suboptions...12.2(33) SRE on 7200 supports this
feature...

basically the giaddr must be derived from server-id-override suboption
by the IOS DHCP server which is not happening on older IOS.....thts
the reason you are seeing the error "there is no address pool for
10.1.1.2." on R1.

this feature set is needed on IOS DHCP server, relay agent can use an
older image.

HTH

Swap
#19804

On Sun, Jan 31, 2010 at 11:01 PM, Gavin Schokman
<g_schokman_at_yahoo.com.au> wrote:
> Hi group,
>
> Been playing with DHCP and its various configurations today and came up
> against some pain when trying to implement the configs in "DHCP Relay Agent
> Support for MPLS VPNs".
> The issue I'm having is I can configure the Relay Agent to send the VPN
> sub-options to the DHCP server, but I can't get the DHCP server to allocate
> an IP address from the VPN-specific pool.
> See topology below:
>
> Please view in a fixed-width font such as Courier.
>
> |
> 10.1.1.1/24 | +---+
> +---+ | +------+R3 |
> |R1 +--------+ 10.1.1.2/24 10.1.2.2/24| +---+
> +---+ | vrf: Global +---+ vrf: RED |
> +-------------+R2 +------------+
> DHCP Server | +---+ | DHCP Clients
> Cisco IOS | |
> DHCP Relay | +---+
> Agent +------+R4 |
> Cisco IOS | +---+
>
>
>
> R1 config:
>
> ip dhcp pool NET-2-RED
> vrf RED
> network 10.1.2.0 255.255.255.0
> default-router 10.1.2.2
> dns-server 192.168.100.100
> domain-name relay.com
>
>
> ip vrf RED
> rd 1:1
> route-target export 1:1
> route-target import 1:1
> !
>
>
> R2 config:
>
> ip dhcp relay information option
>
> ip vrf RED
> rd 1:1
> vpn id 1:1
> route-target export 1:1
> route-target import 1:1
>
> interface FastEthernet0/1
> ip dhcp relay information option vpn-id
> ip vrf forwarding RED
> ip address 10.1.2.2 255.255.255.0
> ip helper-address vrf global 10.1.1.1
>
>
>
> Now, when R3 or R4 attempts to get an address via DHCP, R2 sends the request
> to R1 with VPN sub-options:
>
> (R2 debug output)
> R2#sh debugging
> DHCP server event debugging is on.
> DHCPC:
> DHCP client activity debugging is on (detailed)
>
> *Mar 1 00:56:23.423: DHCPD: htype 1 chaddr c402.0a04.0001
> *Mar 1 00:56:23.427: DHCPD: remote id 020a00000a01020201000000
> *Mar 1 00:56:23.427: DHCPD: circuit id 00000000
> *Mar 1 00:56:23.431: DHCPD: table id 1 = vrf RED
> *Mar 1 00:56:23.431: DHCPD: VPN id =1:1
> *Mar 1 00:56:23.435: DHCPD: Selected subnet=10.1.2.0
> *Mar 1 00:56:23.435: DHCPD: Server-id-override=10.1.2.2
> *Mar 1 00:56:23.439: DHCPD: giaddr changed to 10.1.1.2
> *Mar 1 00:56:56.663: DHCPD: Sending notification of DISCOVER:
> *Mar 1 00:56:56.663: DHCPD: htype 1 chaddr c402.0a04.0001
> *Mar 1 00:56:56.667: DHCPD: remote id 020a00000a01020201000000
> *Mar 1 00:56:56.667: DHCPD: circuit id 00000000
> *Mar 1 00:56:56.671: DHCPD: table id 1 = vrf RED
> *Mar 1 00:56:56.671: DHCPD: Seeing if there is an internally specified pool
> class:
>
> But R1 complains that it doesn't have an address pool for R2's address on
> the 10.1.1.0/24 subnet (i.e. the subnet between R1 & R2)
>
> (R1 debug output)
> R1#sh debugging
> DHCP server event debugging is on.
> DHCPC:
> DHCP client activity debugging is on (detailed)
>
> *Mar 1 00:58:26.823: DHCPD: Sending notification of DISCOVER:
> *Mar 1 00:58:26.823: DHCPD: htype 1 chaddr c402.0a04.0001
> *Mar 1 00:58:26.827: DHCPD: remote id 020a00000a01010100000000
> *Mar 1 00:58:26.827: DHCPD: circuit id 00000000
> *Mar 1 00:58:26.831: DHCPD: Seeing if there is an internally specified pool
> class:
> *Mar 1 00:58:26.831: DHCPD: htype 1 chaddr c402.0a04.0001
> *Mar 1 00:58:26.835: DHCPD: remote id 020a00000a01010100000000
> *Mar 1 00:58:26.835: DHCPD: circuit id 00000000
> *Mar 1 00:58:26.839: DHCPD: there is no address pool for 10.1.1.2.
>
>
> This is driving me quite batty at the moment! The only thing I can think of
> is that IOS can't act as the DHCP server when using the VPN sub-options.
> Does anyone have any suggestions/experience with this feature??
>
> Cheers,
> Gavin
>
>
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Received on Mon Feb 01 2010 - 02:08:02 ART