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Table Of Contents  The TCP/IP Guide
 9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)
      9  TCP/IP Network Configuration and Management Protocols (BOOTP, DHCP, SNMP and RMON)
           9  Host Configuration and TCP/IP Host Configuration Protocols (BOOTP and DHCP)
                9  TCP/IP Dynamic Host Configuration Protocol (DHCP)
                     9  DHCP Messaging, Message Types and Formats

Previous Topic/Section
DHCP Options, Option Format and "Option Overloading"
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12
3
456
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DHCP Client/Server Implementation, Features and Issues
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Summary Of DHCP Options / BOOTP Vendor Information Fields
(Page 3 of 6)

IP Layer Parameters Per Host

These are parameters that control the operation of IP on a host as a whole (not interface-specific) see Table 193.


Table 193: DHCP/BOOTP Options: IP Layer Parameters Per Host

Code Value

Data Length (bytes)

Name and Description

19

1

IP Forwarding Enable/Disable: A value of 1 turns on IP forwarding (that is, routing) on a client that is capable of that function; a value of 0 turns it off.

20

1

Non-Local Source Routing Enable/Disable Option: A value of 1 tells a client capable of routing to allow forwarding of IP datagrams with non-local source routes. A value of 0 tells the client not to allow this.

See the
source routing IP datagram option for a bit more information on this and option #21 below.

21

Variable (Multiple of 8)

Policy Filter: A set of address/mask pairs used to filter non-local source-routed datagrams.

22

2

Maximum Datagram Reassembly Size: Tells the client the size of the largest datagram that the client should be prepared to reassemble. The minimum value is 576 bytes.

23

1

Default IP Time-To-Live: Specifies the default value that the client should use for the Time To Live field in creating IP datagrams.

24

4

Path MTU Aging Timeout: Specifies the number of seconds the client should use in aging path MTU values determined using Path MTU discovery.

25

Variable (Multiple of 2)

Path MTU Plateau Table: Specifies a table of values to be used in performing path MTU discovery.


IP Layer Parameters Per Interface

These parameters are specific to a particular host interface at the IP level (Table 194)


Table 194: DHCP/BOOTP Options: IP Layer Parameters Per Interface

Code Value

Data Length (bytes)

Name and Description

26

2

Interface MTU: Specifies the maximum transmission unit (MTU) to be used for IP datagrams on this interface. Minimum value is 68.

27

1

All Subnets Are Local: When set to 1, tells the client that it may assume that all subnets of the IP network it is on have the same MTU as its own subnet. When 0, the client must assume that some subnets may have smaller MTUs than the client's subnet.

28

4

Broadcast Address: Tells the client what address it should use for broadcasts on this interface.

29

1

Perform Mask Discovery: A value of 1 tells the client that it should use ICMP to discover a subnet mask on the local subnet. A value of 0 tells the client not to perform this discovery.

30

1

Mask Supplier: Set to 1 to tell the client that it should respond to ICMP subnet mask requests on this interface.

31

1

Perform Router Discovery: A value of 1 tells the client to use the ICMP router discovery process to solicit a local router. A value of 0 tells the client to not do so. Note that DHCP itself can be used to specify one or more local routers using option #3 above.

32

4

Router Solicitation Address: Tells the client the address to use as the destination for router solicitations.

33

Variable (Multiple of 8)

Static Route: Provides the client with a list of static routes it can put into its routing cache. The list consists of a set of IP address pairs; each pair defines a destination and a router to be used to reach the destination.


Previous Topic/Section
DHCP Options, Option Format and "Option Overloading"
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Pages in Current Topic/Section
12
3
456
Next Page
DHCP Client/Server Implementation, Features and Issues
Next Topic/Section

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