DHCP on-deman pool

ODAP allows importing DHCP settings using various methods, one of them being IPCP (Internet Protocol Control Protocol for PPP). IPCP allows importing an IP address along with the subnet mask (while PPP ignores the mask, DHCP can use it) as well as DNS/WINS servers. This is useful in PPPoE deployments,

such as with DSL, where the DSL CPE router gets an address assignmentthrough DHCP from the provider, and forwards options such as DNS to the clients behind the CPE.To verify this check the DHCP pool settings and verify the imported parameters

R2 - R3 encapsulation PPP. Config f0/0 R3 nhan dia chi ipaddress tu R2.

R2: interface Serial1/0  ip address 10.1.23.2 255.255.255.0  encapsulation ppp  no peer neighbor-route  peer default ip address 10.1.23.3  ppp ipcp mask 255.255.255.0

R3: interface Serial1/0  ip address negotiated  encapsulation ppp  no peer neighbor-route  ppp ipcp mask request

When R3 receives RIP updates from R2 they are discarded because they are on different networks. This is due to the fact that R3 uses the host route 10.1.23.3/32, and R2 is outside this range. To resolve this R3 must disable the update source validation feature. Additionally the peer-neighbor-route feature is disabled so that R3 does not inject R2’s IP address as a host route into the routing domain.

Hoac

R3#show run | se router rip

router rip

 version 2

 no validate-update-source

 network 0.0.0.0

 no auto-summary