B-5
User Guide for Cisco Network Registrar, 7.1
OL-16002-01
Appendices, Glossary, and Index
Appendix B DHCP Options
Option Descriptions
TCP Parameters
lists the options that affect the operation of the TCP layer on a per-interface basis.
Application and Service Parameters
lists some miscellaneous options used to configure miscellaneous applications and services.
ARP Cache
Timeout
35
4 octets Timeout in seconds for ARP cache entries.
Ethernet
Encapsulation
36
1 octet
Specifies whether or not the client should use Ethernet Version 2 (RFC
894) or IEEE 802.3 (RFC 1042) encapsulation if the interface is an
Ethernet.
Value: 0=use RFC 894 encapsulation; 1=use RFC 1042 encapsulation
Table B-4
Link Layer Parameters Per Interface Options (continued)
Option Name
No. Length
Description
Table B-5
TCP Parameter Options
Option Name
No. Length
Description
TCP Default
TTL
37
1 octet
Default TTL that the client should use when 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=do not generate
keepalive messages unless specifically requested.
TCP Keepalive
Garbage
39
1 octet
Specifies the whether or not the client should send TCP keep-alive
messages with an octet of garbage for compatibility with older
implementations.
Values: 0=do not send; 1=send
Table B-6
Application and Service Parameter Options
Option Name
No. Length
Description
Network
Information
Service (NIS)
Domain
40
1 octet minimum
Name of the client NIS domain. The domain is formatted
as a character string consisting of characters from the NVT
ASCII character set.
Network
Information
Service (NIS)
Servers
41
4 octet minimum;
multiples of 4
List of IP addresses indicating NIS servers available to the
client. Servers should be in order of preference.
