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Selecting DHCP Parameters

The SAE sends a set of parameters to the DHCP server in the JUNOSe router. The DHCP server determines the IP address offered, as well as the options sent to the DHCP client. The parameters comprise IP address authorization parameters, as well as parameters stored in a DHCP profile. Parameters in the DHCP profile override authorization parameters.

For more information about how the SAE handles DHCP subscribers, see:

Setting DHCP Parameters with DHCP Options

NOTE: JUNOSe routers do not currently support the functionality described in this section. DHCP options and BOOTP options that the SAE sends to the JUNOSe router are ignored.


DHCP servers use DHCP options to configure DHCP clients. The DHCP local server in the JUNOSe router supports a subset of DHCP options. The SAE supports all DHCP options defined in RFC 2132—DHCP Options and BOOTP Vendor Extensions (March 1997) by name. It also supports other options, but you need to specify them by number and type. The DHCP options allow a flexible definition of parameters offered to DHCP subscribers. For example, they allow integration with cable modems or set-top boxes because you can configure options to control the boot sequence of these devices.

You can configure DHCP options in DHCP profiles and in DHCP classification scripts. Table 6 lists the name, number, and type of all supported DHCP options. You can use these fields to configure DHCP options.

The following example shows how to specify an option by number and by type. The two statements identify the same option:

dhcp[12]

dhcp['host-name']

In SDX software earlier than Release 4.2, you had to include the option type in your option definition. For example:

dhcp[12].string = HOST

You can now write:

dhcp[12] = HOST

Note that the earlier method of defining options still works in Release 4.2 and later.




Table 6: DHCP Options Supported on the SAE  
Option Name
Option Number
Option Type

subnet-mask

1

ip-address

time-offset

2

int32

routers

3

ip-address

time-servers

4

ip-address

ien116-name-servers

5

ip-address

domain-name-servers

6

ip-address

log-servers

7

ip-address

cookie-servers

8

ip-address

lpr-servers

9

ip-address

impress-servers

10

ip-address

resource-location-servers

11

ip-address

host-name

12

string

boot-size

13

int16

merit-dump

14

string

domain-name

15

string

swap-server

16

ip-address

root-path

17

string

extension-path

18

string

ip-forwarding

19

int8

non-local-source-routing

20

int8

policy-filter

21

ip-address

max-dgram-reassembly

22

int16

default-ip-ttl

23

int8

path-mtu-aging-timeout

24

int32

path-mtu-plateau-table

25

int16

interface-mtu

26

int16

all-subnets-local

27

int8

broadcast-address

28

ip-address

perform-mask-discovery

29

int8

mask-supplier

30

int8

router-discovery

31

int8

router-solicitation-address

32

ip-address

static-routes

33

ip-address

trailer-encapsulation

34

int8

arp-cache-timeout

35

int32

ieee802-3-encapsulation

36

int8

default-tcp-ttl

37

int8

tcp-keepalive-interval

38

int32

tcp-keepalive-garbage

39

int8

nis-domain

40

string

nis-servers

41

ip-address

ntp-servers

42

ip-address

netbios-name-servers

44

ip-address

netbios-dd-server

45

ip-address

netbios-node-type

46

int8

netbios-scope

47

string

font-servers

48

ip-address

x-display-manager

49

ip-address

requested-ip-address

50

ip-address

ip-address-lease-time

51

int32

option-overload

52

int8

dhcp-msg-type

53

int8

server-identifier

54

ip-address

parameter-request-list

55

data-string

message

56

string

maximum-dhcp-msg-size

57

int16

renewal-time

58

int32

rebinding-time

59

int32

vendor-class-identifier

60

data-string

client-identifier

61

data-string

nisplus-domain

64

string

nisplus-servers

65

ip-address

tftp-server-name

66

string

bootfile-name

67

string

mobile-ip-home-agent

68

ip-address

smtp-server

69

ip-address

pop-server

70

ip-address

nntp-server

71

ip-address

www-server

72

ip-address

finger-server

73

ip-address

irc-server

74

ip-address

streettalk-server

75

ip-address

streetalk-directory-assistance-server

76

ip-address


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