AlcatelLucent_Hor_2col_lrg

7705 SAR

R6.0 Configuration Note

DHCP on Interface Configuration Notes

Last Updated: 2013-01-18

Version 1.0

Introduction:

The DHCP client features allows an interface within the core routing instance to be configured to received an IP address from a DHCP server.

Setup:

Prerequisites:

- DHCP server

For this config note a DHCP daemon running on a Linux server was used. DHCP daemon server configuration used was as follows:

dhcpd.conf

subnet 10.255.0.0 netmask 255.255.0.0 {

range 10.255.1.1 10.255.1.254;

option subnet-mask 255.255.0.0;

option routers 10.255.0.1;

default-lease-time 0;

max-lease-time 0;

} exit

Configuration Scenario 1:

On the 7705 SAR create an interface in the core routing instance. To enable the interface to receive an IP address from the DHCP server, configure the interface address as follows:

*A:SARW-141# configure router interface to-DHCP

*A:SARW-141>config>router>if# info

----------------------------------------------

address dhcp

port 1/1/5

----------------------------------------------

By doing so, the 7705 SAR will begin the DHCP process and receive an address from the DHCP server. In this case, the 7705 SAR will receive an address within the 10.255.0.0/16 range.

*A:SARW-141# show router interface

===============================================================================

Interface Table (Router: Base)

===============================================================================

Interface-Name Adm Opr(v4/v6) Mode Port/SapId

IP-Address PfxState

-------------------------------------------------------------------------------

system Up Up/Down Network system

10.10.10.141/32 n/a

to-DHCP Up Up/Down Network 1/1/5

10.255.1.1/16 n/a

-------------------------------------------------------------------------------

Interfaces : 2

If the DHCP address needs to be released, issue a ‘no address’ command under the interface, as follows:

*A:SARW-141# configure router interface to-DHCP no address

To renew the lease simply re-enable the dhcp client with the ‘address dhcp’ command.

*A:SARW-141# configure router interface to-DHCP address dhcp

There are two parameters that can be specified when configuring an interface to use DHCP to receive an IP address. The two parameters are ‘client-identifier’ and ‘vendor-class-id’. These are both optional, however if used they allow for the DHCP server to make a decision as to the treatment of the DHCP request from the 7705 SAR.

Verification and Troubleshooting:

To verify whether or not the address configured under an interface was acquired using DHCP or statically assigned issue the following command (Note if a client identifier or vendor class is configured it will also be displayed here):

A:SARW-141# show router interface to-DHCP detail

===============================================================================

Interface Table (Router: Base)

===============================================================================

-------------------------------------------------------------------------------

Interface

-------------------------------------------------------------------------------

If Name : to-DHCP

Admin State : Up Oper (v4/v6) : Up/Down

Protocols : LDP

IP Addr/mask : 10.255.1.1/16 Address Type : Primary

IGP Inhibit : Disabled Broadcast Address : Host-ones

-------------------------------------------------------------------------------

Details

-------------------------------------------------------------------------------

Description : (Not Specified)

If Index : 2 Virt. If Index : 2

Last Oper Chg : 01/01/2000 05:38:09 Global If Index : 127

Port Id : 1/1/5

TOS Marking : Trusted If Type : Network

Egress Filter : none Ingress Filter : none

Egr IPv6 Flt : none Ingr IPv6 Flt : none

SNTP B.Cast : False QoS Policy : 1

Queue-group : None

MAC Address : 34:aa:99:eb:d6:75 Arp Timeout : 14400

IP Oper MTU : 1558 ICMP Mask Reply : True

Arp Populate : Disabled

LdpSyncTimer : None Strip-Label : Disabled

LSR Load Balance : system

uRPF Chk : disabled

uRPF Fail Bytes : 0 uRPF Chk Fail Pkts: 0

Rx Pkts : 3103 Rx Bytes : 271128

Rx V4 Pkts : 3103 Rx V4 Bytes : 271128

Rx V6 Pkts : 0 Rx V6 Bytes : 0

Tx V4 Pkts : 2495 Tx V4 Bytes : 250480

Tx V6 Pkts : 0 Tx V6 Bytes : 0

Proxy ARP Details

Rem Proxy ARP : Disabled Local Proxy ARP : Disabled

Policies : none

Proxy Neighbor Discovery Details

Local Pxy ND : Disabled

Policies : none

DHCP Details

Description : (Not Specified)

Admin State : Down

Action : Keep Copy To Opt43 : Disabled

ICMP Details

Unreachables : Number - 100 Time (seconds) - 10

TTL Expired : Number - 100 Time (seconds) - 10

IPCP Address Extension Details

Peer IP Addr : Not configured

Peer Pri DNS Addr: Not configured

Peer Sec DNS Addr: Not configured

DHCP CLIENT Details

DHCP Client :Enabled

client-id:n/a

vendor-id:n/a

======================================================================================

Configuration Scenario 2:

Some deployments may require the 7705 SAR to be connected to another 7705 SAR or 7750 SR acting as a DHCP relay. The following configurations outline steps required for configuration of both 7705s, one as a DHCP relay and one as a DHCP client.

In this config note a new address range was configured on the DHCP server. The new range allocates one IP within the 10.130.141.0/31 network.

subnet 10.130.141.0 netmask 255.255.255.254 {

range 10.130.141.1 10.130.141.1;

option subnet-mask 255.255.255.254;

option routers 10.130.141.0;

default-lease-time 0;

max-lease-time 0;

}

Once the DHCP server is configured, SAR-130 needs to be configured so that it can relay DHCP messages from SAR-141 to the DHCP server. This is functionality is known as DHCP relay. SAR-130 will relay the DHCP messages from SAR-141 to the DHCP server and vice versa. Configuration of the interfaces on SAR-130 are as follows:

*A:SAR18-130# configure router interface to-141

*A:SAR18-130>config>router>if# info

----------------------------------------------

address 10.130.141.0/31

port 1/8/2

dhcp

server 10.255.0.1

no shutdown

exit

----------------------------------------------

*A:SAR18-130>config>router>if# back

*A:SAR18-130>config>router# interface to-DHCP

*A:SAR18-130>config>router>if# info

----------------------------------------------

address 10.255.0.2/16

port 1/8/3

----------------------------------------------

*A:SAR18-130>config>router>if#Interfaces : 2

Nodte the DHCP parameters on the interfaced to-141. The DHCP’s address is specified so that any DHCP packet that ingress this interface get forwarded to the appropriate DHCP server.

Configuration on node SARW-141 is the same as previously configured when the node was directly connected to the DHCP server. Simply configure the address under the interface facing SAR18-130 for DHCP as follows:

*A:SARW-141# configure router interface to-130 address dhcp

SARW-141 should receive an address in the 10.130.140.0/31 range, in fact it can only receive one address as per our DHCP daemon configuration.

*A:SARW-141# show router interface

===============================================================================

Interface Table (Router: Base)

===============================================================================

Interface-Name Adm Opr(v4/v6) Mode Port/SapId

IP-Address PfxState

-------------------------------------------------------------------------------

system Up Up/Down Network system

10.10.10.141/32 n/a

to-130 Up Up/Down Network 1/1/5

10.130.141.1/31 n/a

-------------------------------------------------------------------------------

Interfaces : 2

===============================================================================

Verification and Troubleshooting:

A:SARW-141# show router interface to-130 detail

===============================================================================

Interface Table (Router: Base)

===============================================================================

-------------------------------------------------------------------------------

Interface

-------------------------------------------------------------------------------

If Name : to-130

Admin State : Up Oper (v4/v6) : Up/Down

Protocols : LDP

IP Addr/mask : 10.130.141.1/31 Address Type : Primary

IGP Inhibit : Disabled Broadcast Address : Host-ones

-------------------------------------------------------------------------------

Details

-------------------------------------------------------------------------------

Description : (Not Specified)

If Index : 2 Virt. If Index : 2

Last Oper Chg : 01/01/2000 05:38:09 Global If Index : 127

Port Id : 1/1/5

TOS Marking : Trusted If Type : Network

Egress Filter : none Ingress Filter : none

Egr IPv6 Flt : none Ingr IPv6 Flt : none

SNTP B.Cast : False QoS Policy : 1

Queue-group : None

MAC Address : 34:aa:99:eb:d6:75 Arp Timeout : 14400

IP Oper MTU : 1558 ICMP Mask Reply : True

Arp Populate : Disabled

LdpSyncTimer : None Strip-Label : Disabled

LSR Load Balance : system

uRPF Chk : disabled

uRPF Fail Bytes : 0 uRPF Chk Fail Pkts: 0

Rx Pkts : 3103 Rx Bytes : 271128

Rx V4 Pkts : 3103 Rx V4 Bytes : 271128

Rx V6 Pkts : 0 Rx V6 Bytes : 0

Tx V4 Pkts : 2495 Tx V4 Bytes : 250480

Tx V6 Pkts : 0 Tx V6 Bytes : 0

Proxy ARP Details

Rem Proxy ARP : Disabled Local Proxy ARP : Disabled

Policies : none

Proxy Neighbor Discovery Details

Local Pxy ND : Disabled

Policies : none

DHCP Details

Description : (Not Specified)

Admin State : Down

Action : Keep Copy To Opt43 : Disabled

ICMP Details

Unreachables : Number - 100 Time (seconds) - 10

TTL Expired : Number - 100 Time (seconds) - 10

IPCP Address Extension Details

Peer IP Addr : Not configured

Peer Pri DNS Addr: Not configured

Peer Sec DNS Addr: Not configured

DHCP CLIENT Details

DHCP Client :Enabled

client-id:n/a

vendor-id:n/a