background image

 

B-1

User Guide for Cisco Network Registrar, 7.1

OL-16002-01

A P P E N D I X

B

DHCP Options

DHCP provides a framework for passing configuration information to hosts on a TCP/IP network. 
Configuration parameters and other control information are carried in tagged data items that are stored 
in the options field of the DHCP message. The data items themselves are also called options.

This appendix contains DHCP options and BOOTP vendor extensions from RFC 2132, and includes the 
validation type for each option, as indicated in 

Table B-10 on page B-14

.

This appendix also contains the standard Microsoft client options and several tables displaying the 
options sorted by categories.

Option Descriptions

The following sections describe the DHCP options in detail:

RFC 1497 Vendor Extensions, page B-1

IP Layer Parameters Per Host, page B-3

IP Layer Parameters Per Interface, page B-4

Link Layer Parameters Per Interface, page B-4

TCP Parameters, page B-5

Application and Service Parameters, page B-5

DHCPv4 Extension Options, page B-8

DHCPv6 Options, page B-10

Microsoft Client Options, page B-13

Options by Number, page B-14

Options by Network Registrar Name, page B-18

Option Validation Types, page B-24

RFC 1497 Vendor Extensions

Table B-1 on page B-2

 lists the vendor extensions as defined in RFC 1497.

Summary of Contents for SDVR-10P-160

Page 1: ...B 14 This appendix also contains the standard Microsoft client options and several tables displaying the options sorted by categories Option Descriptions The following sections describe the DHCP options in detail RFC 1497 Vendor Extensions page B 1 IP Layer Parameters Per Host page B 3 IP Layer Parameters Per Interface page B 4 Link Layer Parameters Per Interface page B 4 TCP Parameters page B 5 A...

Page 2: ...Domain Name System STD 13 RFC 1035 name servers available to the client Servers should be in order of preference Log Server 7 4 octet minimum multiples of 4 List of MIT LCS UDP log servers available to the client Servers should be in order of preference Cookie Server 8 4 octet minimum multiples of 4 List of RFC 865 compliant cookie servers available to the client Servers should be in order of pref...

Page 3: ...ent should configure its IP layer for packet forwarding Values 0 disable 1 enable Non Local SourceRouting Enable Disable 20 1 octet Specifies whether the client should configure its IP layer to allow forwarding of datagrams with non local source routes Values 0 disable 1 enable Policy Filter 21 8 octet minimum multiples of 8 Policy filters for non local source routing The filters consist of a list...

Page 4: ...et Perform Mask Discovery 29 1 octet Specifies whether or not the client should perform subnet mask discovery using ICMP Values 0 disable 1 enable Mask Supplier 30 1 octet Specifies whether or not the client should respond to subnet mask requests using ICMP Values 0 do not respond 1 respond PerformRouter Discovery 31 1 octet Specifies whether or not the client should solicit routers using the Rout...

Page 5: ...n sending TCP segments Value minimum 1 TCP Keepalive Interval 38 4 octets Interval in seconds that the client TCP should wait before sending a keepalive message on a TCP connection The time is specified as a 32 bit unsigned integer A value of zero indicates that the client should not generate keepalive messages on connections unless specifically requested by an application Value 32 bit unsigned 0 ...

Page 6: ...m of information in this option then the vendor should encode the option using encapsulated vendor specific options as described here The encapsulated vendor specific options field should be encoded as a sequence of code length and value fields of identical syntax to the DHCP options field with these exceptions There should not be a magic cookie field in the encapsulated vendor specific extensions...

Page 7: ...aracter string consisting of characters from the NVT ASCII character set Network Information Service NIS Servers 65 4 octet minimum multiples of 4 List of IP addresses indicating NIS servers available to the client Servers should be in order of preference Mobile IP Home Agent 68 0 octets minimum multiples of 4 expected 4 octets single home agent address List of IP addresses indicating mobile IP ho...

Page 8: ...ted IP Address 50 4 octets Used in a client request DHCPDISCOVER to allow the client to request that a particular IP address be assigned IP Address Lease Time 51 4 octets Used in a client request DHCPDISCOVER or DHCPREQUEST to allow the client to request a lease time for the IP address In a server reply DHCPOFFER a DHCP server uses this option to specify the lease time it is willing to offer Value...

Page 9: ...DECLINE message to indicate why the client declined the offered parameters The message consists of n octets of NVT ASCII text which the client can display on an available output device Maximum DHCP Message Size 57 2 octets Maximum length DHCP message that a server is willing to accept The length is specified as an unsigned 16 bit integer A client can use the maximum DHCP message size option in DHC...

Page 10: ...identifier other than a hardware address for example a fully qualified domain name For correct identification of clients each client identifier must be unique among the client identifiers used on the subnet to which the client is attached Vendors and system administrators are responsible for choosing client identifiers that meet this requirement for uniqueness TFTP Server Name 66 1 octet minimum I...

Page 11: ...on request message to inform the server about options the client wants from the server A server can include this option in a Reconfigure message to indicate which option updates the client should request preference AT_INT8 7 A server sends this option to a client to affect what server the client selects Mod elapsed time AT_SHORT 8 A client sends this option to a server to indicate how long the cli...

Page 12: ...n identity association and its associated parameters and prefixes Parameters are the unique ID time the client contacts the addresses in the IA to extend the lifetime and time the client contacts any available server to extend the lifetime of the addresses iaprefix AT_BLOB 26 IPv6 prefixes associated with an IA_PD The prefix must be encapsulated in the options field of an IA_PD option Parameters a...

Page 13: ... type link address or 0 0 and options to provide data needed for the query client data AT_BLOB 45 Encapsulates the data for a single client on a single link in a LEASEQUERY REPLY message clt time AT_TIME 46 Client last transaction time encapsulated in the client data option identifies how long ago the server last communicated with the client in seconds lq relay data AT_BLOB 47 Used only in a LEASE...

Page 14: ...currences 2n means multiple occurrences in multiples of 2 Comments also indicate whether the option includes suboptions and if so how many and whether the option is nonmodifiable NM Tip For the syntax for adding more complex option data values for suboptions see the Adding Complex Values for Suboptions section on page 21 7 domain name servers 6 IP address of the name servers netbios name servers 4...

Page 15: ...out MTU Timeout AT_TIME 25 path mtu plateau tables MTU Plateau AT_RANGESHORT 2n 26 interface mtu MTU Interface AT_RANGESHORT 27 all subnets local MTU Subnet AT_BOOL 28 broadcast address Broadcast Address AT_IPADDR 29 perform mask discovery Mask Discovery AT_BOOL 30 mask supplier Mask Supplier AT_BOOL 31 router discovery Router Discovery AT_BOOL 32 router solicitation address Router Request AT_IPAD...

Page 16: ... AT_INT8 0 56 dhcp message DHCP Message AT_NSTRING NM 57 dhcp max message size DHCP Maximum Message Size AT_SHORT NM 58 dhcp renewal time Renewing Time AT_TIME NM 59 dhcp rebinding time Rebinding Time AT_TIME NM 60 dhcp class identifier Class Identifier AT_NSTRING 61 dhcp client identifier Client Identifier AT_BLOB 62 netwareip domain NetWare IP Domain AT_NSTRING 63 netwareip information NetWare I...

Page 17: ...S Servers AT_IPADDR 1 86 nds tree NDS Tree Name AT_NSTRING 87 nds context NDS Context AT_NSTRING 88 bcms servers d BCMS Controller Domain RFC 4280 AT_DNSNAME 1 89 bcms servers a BCMS Address AT_IPADDR 1 90 authentication Authentication AT_BLOB Suboptions 5 91 client last transaction time Lease Query Client Last Transaction Time AT_TIME 92 associated ip Lease Query Associated IP Addresses AT_IPADDR...

Page 18: ...bleLabs Client Configuration AT_BLOB Suboptions 10 see cablelabs client configuration page C 3 123 geo conf GeoConf Option AT_BLOB 124 v i vendor class Vendor Identifying Vendor Class AT_VENDOR_CLASS NM 125 v i vendor info Vendor Identifying Vendor Specific Info AT_VENDOR_OPTS See also the cablelabs 125 suboptions in Table C 3 on page C 2 128 mcns security server AT_IPADDR 161 cisco leased ip Cisc...

Page 19: ...leLabs Client Configuration Interface cisco autoconfigure 251 Cisco Autoconfiguration DHCPv4 cisco client last transaction time 163 Cisco Client Last Transaction Time DHCPv4 cisco client requested host name 162 Cisco Client Requested Host Name DHCPv4 cisco leased ip 161 Cisco Leased IP Address DHCPv4 cisco vpn id 221 Cisco VPN Identifier DHCPv4 classless static route 121 Classless Static Route DHC...

Page 20: ...DHCPv6 domain name 15 Domain Name Basic MS DHCP Client domain name servers 6 Domain Name Server Basic MS DHCP Client domain search 119 Domain Search DHCPv4 elapsed time 8 Elapsed Time DHCPv6 end 255 End ero 43 Relay Agent Echo Request Option DHCPv6 extensions path 18 Extensions Path BOOTP finger servers 73 Finger Server Servers font servers 48 X Window System Font Server Servers geo conf 123 GeoCo...

Page 21: ...bile IP Home Agent Servers name servers 5 Name Server BOOTP name service search 117 Name Service Search DHCPv4 nds context 87 NDS Context NetWare Client nds servers 85 NDS Servers NetWare Client nds tree 86 NDS Tree Name NetWare Client netbios dd servers 45 NetBIOS over TCP IP Datagram Distribution Server WINS NetBIOS netbios name servers 44 NetBIOS over TCP IP Name Server WINS NetBIOS MS DHCP Cli...

Page 22: ...cy Filter Host IP pop3 servers 70 POP3 Server Servers preference 7 Preference DHCPv6 rapid commit 80 Rapid Commit DHCPv4 rapid commit 14 Rapid Commit DHCPv6 reconfigure accept 20 Reconfigure Accept DHCPv6 reconfigure message 19 Reconfigure Message DHCPv6 relay agent info 82 DHCP Relay Agent Information DHCPv4 relay agent subscriber id 38 Relay Agent Subscriber ID DHCPv6 relay message 9 Relay Messa...

Page 23: ...e Garbage Interface tcp keepalive interval 38 TCP Keepalive Interval Interface tftp server 66 TFTP Server Name Servers time offset 2 Time Offset BOOTP time servers 4 Time Server BOOTP trailer encapsulation 34 Trailer Encapsulation Interface tz database 101 TZ Database String DHCPv4 tz posix 100 IEEE 1003 1 String DHCPv4 user auth 98 User Authentication DHCPv4 user class 15 User Class DHCPv6 vendor...

Page 24: ...dress MAC address AT_MESSAGE Unsigned 8 bit message not usable for custom options AT_NOLEN No length used for PAD and END only AT_NSTRING Sequence of ASCII characters string AT_OVERLOAD Overload bytes not usable for custom options AT_RANGEBYTE Range of bytes not usable for custom options AT_RANGESHORT Range of shorts not usable for custom options AT_RDNSNAME Relative DNS name relative DNS name AT_...

Page 25: ...e For the DHCPv6 user class option 15 the repeating pattern is len 2 byte data of single type AT_VENDOR_CLASS Vendor class option enterprise ID followed by opaque data if DHCPv4 enterprise ID is followed by EID length vendor class AT_VENDOR_OPTS Vendor specific options data enterprise ID followed by TLVs of vendor specific data if DHCPv4 enterprise ID is followed by EID length vendor opts AT_ZEROS...

Page 26: ...B 26 User Guide for Cisco Network Registrar 7 1 OL 16002 01 Part 6 Appendices Glossary and Index Appendix B DHCP Options Option Tables ...

Reviews: