Dynamic Host Configuration Protocol (DHCP) and Bootstrap Protocol (BOOTP) Parameters

Last Updated
2026-02-02
Note
For the Civic Address Types Registry [RFC 4776], please see:
http://www.iana.org/assignments/civic-address-types-registry
Available Formats

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Registries Included Below

BOOTP Vendor Extensions and DHCP Options

Registration Procedure(s)
IETF Review
Reference
[RFC 2939]
Note
The Bootstrap Protocol (BOOTP) [RFC 951] describes an IP/UDP bootstrap
protocol (BOOTP) which allows a diskless client machine to discover
its own IP address, the address of a server host, and the name of a
file to be loaded into memory and executed.  The Dynamic Host
Configuration Protocol (DHCP) [RFC 2131] provides a framework for
automatic configuration of IP hosts.  The document "DHCP Options and
BOOTP Vendor Information Extensions" [RFC 2132] describes options for
DHCP, some of which can also be used with BOOTP. Additional DHCP
options are described in other RFCs, as documented in this registry.
Available Formats

CSV
Tag Name Data Length Meaning Reference
0 Pad 0 None [RFC 2132]
1 Subnet Mask 4 Subnet Mask Value [RFC 2132]
2 Time Offset 4 Time Offset in Seconds from UTC (note: deprecated by 100 and 101) [RFC 2132]
3 Router N N/4 Router addresses [RFC 2132]
4 Time Server N N/4 Timeserver addresses [RFC 2132]
5 Name Server N N/4 IEN-116 Server addresses [RFC 2132]
6 Domain Server N N/4 DNS Server addresses [RFC 2132]
7 Log Server N N/4 Logging Server addresses [RFC 2132]
8 Quotes Server N N/4 Quotes Server addresses [RFC 2132]
9 LPR Server N N/4 Printer Server addresses [RFC 2132]
10 Impress Server N N/4 Impress Server addresses [RFC 2132]
11 RLP Server N N/4 RLP Server addresses [RFC 2132]
12 Hostname N Hostname string [RFC 2132]
13 Boot File Size 2 Size of boot file in 512 byte chunks [RFC 2132]
14 Merit Dump File N Client to dump and name the file to dump it to [RFC 2132]
15 Domain Name N The DNS domain name of the client [RFC 2132]
16 Swap Server N Swap Server address [RFC 2132]
17 Root Path N Path name for root disk [RFC 2132]
18 Extension File N Path name for more BOOTP info [RFC 2132]
19 Forward On/Off 1 Enable/Disable IP Forwarding [RFC 2132]
20 SrcRte On/Off 1 Enable/Disable Source Routing [RFC 2132]
21 Policy Filter N Routing Policy Filters [RFC 2132]
22 Max DG Assembly 2 Max Datagram Reassembly Size [RFC 2132]
23 Default IP TTL 1 Default IP Time to Live [RFC 2132]
24 MTU Timeout 4 Path MTU Aging Timeout [RFC 2132]
25 MTU Plateau N Path MTU Plateau Table [RFC 2132]
26 MTU Interface 2 Interface MTU Size [RFC 2132]
27 MTU Subnet 1 All Subnets are Local [RFC 2132]
28 Broadcast Address 4 Broadcast Address [RFC 2132]
29 Mask Discovery 1 Perform Mask Discovery [RFC 2132]
30 Mask Supplier 1 Provide Mask to Others [RFC 2132]
31 Router Discovery 1 Perform Router Discovery [RFC 2132]
32 Router Request 4 Router Solicitation Address [RFC 2132]
33 Static Route N Static Routing Table [RFC 2132]
34 Trailers 1 Trailer Encapsulation [RFC 2132]
35 ARP Timeout 4 ARP Cache Timeout [RFC 2132]
36 Ethernet 1 Ethernet Encapsulation [RFC 2132]
37 Default TCP TTL 1 Default TCP Time to Live [RFC 2132]
38 Keepalive Time 4 TCP Keepalive Interval [RFC 2132]
39 Keepalive Data 1 TCP Keepalive Garbage [RFC 2132]
40 NIS Domain N NIS Domain Name [RFC 2132]
41 NIS Servers N NIS Server Addresses [RFC 2132]
42 NTP Servers N NTP Server Addresses [RFC 2132]
43 Vendor Specific N Vendor Specific Information [RFC 2132]
44 NETBIOS Name Srv N NETBIOS Name Servers [RFC 2132]
45 NETBIOS Dist Srv N NETBIOS Datagram Distribution [RFC 2132]
46 NETBIOS Node Type 1 NETBIOS Node Type [RFC 2132]
47 NETBIOS Scope N NETBIOS Scope [RFC 2132]
48 X Window Font N X Window Font Server [RFC 2132]
49 X Window Manager N X Window Display Manager [RFC 2132]
50 Address Request 4 Requested IP Address [RFC 2132]
51 Address Time 4 IP Address Lease Time [RFC 2132]
52 Overload 1 Overload "sname" or "file" [RFC 2132]
53 DHCP Msg Type 1 DHCP Message Type [RFC 2132]
54 DHCP Server Id 4 DHCP Server Identification [RFC 2132]
55 Parameter List N Parameter Request List [RFC 2132]
56 DHCP Message N DHCP Error Message [RFC 2132]
57 DHCP Max Msg Size 2 DHCP Maximum Message Size [RFC 2132]
58 Renewal Time 4 DHCP Renewal (T1) Time [RFC 2132]
59 Rebinding Time 4 DHCP Rebinding (T2) Time [RFC 2132]
60 Class Id N Class Identifier [RFC 2132]
61 Client Id N Client Identifier [RFC 2132]
62 NetWare/IP Domain N NetWare/IP Domain Name [RFC 2242]
63 NetWare/IP Option N NetWare/IP sub Options [RFC 2242]
64 NIS-Domain-Name N NIS+ v3 Client Domain Name [RFC 2132]
65 NIS-Server-Addr N NIS+ v3 Server Addresses [RFC 2132]
66 Server-Name N TFTP Server Name [RFC 2132]
67 Bootfile-Name N Boot File Name [RFC 2132]
68 Home-Agent-Addrs N Home Agent Addresses [RFC 2132]
69 SMTP-Server N Simple Mail Server Addresses [RFC 2132]
70 POP3-Server N Post Office Server Addresses [RFC 2132]
71 NNTP-Server N Network News Server Addresses [RFC 2132]
72 WWW-Server N WWW Server Addresses [RFC 2132]
73 Finger-Server N Finger Server Addresses [RFC 2132]
74 IRC-Server N Chat Server Addresses [RFC 2132]
75 StreetTalk-Server N StreetTalk Server Addresses [RFC 2132]
76 STDA-Server N ST Directory Assist. Addresses [RFC 2132]
77 User-Class N User Class Information [RFC 3004]
78 Directory Agent N directory agent information [RFC 2610]
79 Service Scope N service location agent scope [RFC 2610]
80 Rapid Commit 0 Rapid Commit [RFC 4039]
81 Client FQDN N Fully Qualified Domain Name [RFC 4702]
82 Relay Agent Information N Relay Agent Information [RFC 3046]
83 iSNS N Internet Storage Name Service [RFC 4174]
84 REMOVED/Unassigned [RFC 3679]
85 NDS Servers N Novell Directory Services [RFC 2241]
86 NDS Tree Name N Novell Directory Services [RFC 2241]
87 NDS Context N Novell Directory Services [RFC 2241]
88 BCMCS Controller Domain Name list [RFC 4280]
89 BCMCS Controller IPv4 address option [RFC 4280]
90 Authentication N Authentication [RFC 3118]
91 client-last-transaction-time option [RFC 4388]
92 associated-ip option [RFC 4388]
93 Client System N Client System Architecture [RFC 4578]
94 Client NDI N Client Network Device Interface [RFC 4578]
95 LDAP N Lightweight Directory Access Protocol [RFC 3679]
96 REMOVED/Unassigned [RFC 3679]
97 UUID/GUID N UUID/GUID-based Client Identifier [RFC 4578]
98 User-Auth N Open Group's User Authentication [RFC 2485]
99 GEOCONF_CIVIC [RFC 4776]
100 PCode N IEEE 1003.1 TZ String [RFC 4833]
101 TCode N Reference to the TZ Database [RFC 4833]
102-107 REMOVED/Unassigned [RFC 3679]
108 IPv6-Only Preferred 4 Number of seconds that DHCPv4 should be disabled [RFC 8925]
109 OPTION_DHCP4O6_S46_SADDR 16 DHCPv4 over DHCPv6 Softwire Source Address Option [RFC 8539]
110 REMOVED/Unassigned [RFC 3679]
111 Unassigned [RFC 3679]
112 Netinfo Address N NetInfo Parent Server Address [RFC 3679]
113 Netinfo Tag N NetInfo Parent Server Tag [RFC 3679]
114 DHCP Captive-Portal N DHCP Captive-Portal [RFC 8910]
115 REMOVED/Unassigned [RFC 3679]
116 Auto-Config N DHCP Auto-Configuration [RFC 2563]
117 Name Service Search N Name Service Search [RFC 2937]
118 Subnet Selection Option 4 Subnet Selection Option [RFC 3011]
119 Domain Search N DNS domain search list [RFC 3397]
120 SIP Servers DHCP Option N SIP Servers DHCP Option [RFC 3361]
121 Classless Static Route Option N Classless Static Route Option [RFC 3442]
122 CCC N CableLabs Client Configuration [RFC 3495]
123 GeoConf Option 16 GeoConf Option [RFC 6225]
124 V-I Vendor Class Vendor-Identifying Vendor Class [RFC 3925]
125 V-I Vendor-Specific Information Vendor-Identifying Vendor-Specific Information [RFC 3925]
126 Removed/Unassigned [RFC 3679]
127 Removed/Unassigned [RFC 3679]
128 PXE - undefined (vendor specific) [RFC 4578]
128 Etherboot signature. 6 bytes: E4:45:74:68:00:00
128 DOCSIS "full security" server IP address
128 TFTP Server IP address (for IP Phone software load)
129 PXE - undefined (vendor specific) [RFC 4578]
129 Kernel options. Variable length string
129 Call Server IP address
130 PXE - undefined (vendor specific) [RFC 4578]
130 Ethernet interface. Variable length string.
130 Discrimination string (to identify vendor)
131 PXE - undefined (vendor specific) [RFC 4578]
131 Remote statistics server IP address
132 PXE - undefined (vendor specific) [RFC 4578]
132 IEEE 802.1Q VLAN ID
133 PXE - undefined (vendor specific) [RFC 4578]
133 IEEE 802.1D/p Layer 2 Priority
134 PXE - undefined (vendor specific) [RFC 4578]
134 Diffserv Code Point (DSCP) for VoIP signalling and media streams
135 PXE - undefined (vendor specific) [RFC 4578]
135 HTTP Proxy for phone-specific applications
136 OPTION_PANA_AGENT [RFC 5192]
137 OPTION_V4_LOST [RFC 5223]
138 OPTION_CAPWAP_AC_V4 N CAPWAP Access Controller addresses [RFC 5417]
139 OPTION-IPv4_Address-MoS N a series of suboptions [RFC 5678]
140 OPTION-IPv4_FQDN-MoS N a series of suboptions [RFC 5678]
141 SIP UA Configuration Service Domains N List of domain names to search for SIP User Agent Configuration [RFC 6011]
142 OPTION-IPv4_Address-ANDSF N ANDSF IPv4 Address Option for DHCPv4 [RFC 6153]
143 OPTION_V4_SZTP_REDIRECT N This option provides a list of URIs for SZTP bootstrap servers [RFC 8572]
144 GeoLoc 16 Geospatial Location with Uncertainty [RFC 6225]
145 FORCERENEW_NONCE_CAPABLE 1 Forcerenew Nonce Capable [RFC 6704]
146 RDNSS Selection N Information for selecting RDNSS [RFC 6731]
147 OPTION_V4_DOTS_RI N The name of the peer DOTS agent. [RFC 8973]
148 OPTION_V4_DOTS_ADDRESS N (the minimal length is 4) N/4 IPv4 addresses of peer DOTS agent(s). [RFC 8973]
149 Unassigned [RFC 3942]
150 TFTP server address [RFC 5859]
150 Etherboot
150 GRUB configuration path name
151 status-code N+1 Status code and optional N byte text message describing status. [RFC 6926]
152 base-time 4 Absolute time (seconds since Jan 1, 1970) message was sent. [RFC 6926]
153 start-time-of-state 4 Number of seconds in the past when client entered current state. [RFC 6926]
154 query-start-time 4 Absolute time (seconds since Jan 1, 1970) for beginning of query. [RFC 6926]
155 query-end-time 4 Absolute time (seconds since Jan 1, 1970) for end of query. [RFC 6926]
156 dhcp-state 1 State of IP address. [RFC 6926]
157 data-source 1 Indicates information came from local or remote server. [RFC 6926]
158 OPTION_V4_PCP_SERVER Variable; the minimum length is 5. Includes one or multiple lists of PCP server IP addresses; each list is treated as a separate PCP server. [RFC 7291]
159 OPTION_V4_PORTPARAMS 4 This option is used to configure a set of ports bound to a shared IPv4 address. [RFC 7618]
160 Unassigned Previously assigned by [RFC 7710]; known to also be used by Polycom. [RFC 7710][RFC 8910]
161 OPTION_MUD_URL_V4 N (variable) Manufacturer Usage Descriptions [RFC 8520]
162 OPTION_V4_DNR N Encrypted DNS Server [RFC 9463]
163-174 Unassigned [RFC 3942]
175 Etherboot (Tentatively Assigned - 2005-06-23)
176 IP Telephone (Tentatively Assigned - 2005-06-23)
177 Etherboot (Tentatively Assigned - 2005-06-23)
177 PacketCable and CableHome (replaced by 122)
178-207 Unassigned [RFC 3942]
208 PXELINUX Magic 4 magic string = F1:00:74:7E [RFC 5071][Deprecated]
209 Configuration File N Configuration file [RFC 5071]
210 Path Prefix N Path Prefix Option [RFC 5071]
211 Reboot Time 4 Reboot Time [RFC 5071]
212 OPTION_6RD 18 + N OPTION_6RD with N/4 6rd BR addresses [RFC 5969]
213 OPTION_V4_ACCESS_DOMAIN N Access Network Domain Name [RFC 5986]
214-219 Unassigned
220 Subnet Allocation Option N Subnet Allocation Option [RFC 6656]
221 Virtual Subnet Selection (VSS) Option [RFC 6607]
222-223 Unassigned [RFC 3942]
224-254 Reserved (Private Use)
255 End 0 None [RFC 2132]

DHCP Message Type 53 Values

Registration Procedure(s)
IETF Review
Reference
[RFC 2939]
Available Formats

CSV
Value Message Type Reference
1 DHCPDISCOVER [RFC 2132]
2 DHCPOFFER [RFC 2132]
3 DHCPREQUEST [RFC 2132]
4 DHCPDECLINE [RFC 2132]
5 DHCPACK [RFC 2132]
6 DHCPNAK [RFC 2132]
7 DHCPRELEASE [RFC 2132]
8 DHCPINFORM [RFC 2132]
9 DHCPFORCERENEW [RFC 3203]
10 DHCPLEASEQUERY [RFC 4388]
11 DHCPLEASEUNASSIGNED [RFC 4388]
12 DHCPLEASEUNKNOWN [RFC 4388]
13 DHCPLEASEACTIVE [RFC 4388]
14 DHCPBULKLEASEQUERY [RFC 6926]
15 DHCPLEASEQUERYDONE [RFC 6926]
16 DHCPACTIVELEASEQUERY [RFC 7724]
17 DHCPLEASEQUERYSTATUS [RFC 7724]
18 DHCPTLS [RFC 7724]

NetWare/IP Option Type 63 Sub-Option Codes

Registration Procedure(s)
Not defined
Reference
[RFC 2242]
Available Formats

CSV
Value Message Type Reference
1 NWIP_DOES_NOT_EXIST [RFC 2242]
2 NWIP_EXIST_IN_OPTIONS_AREA [RFC 2242]
3 NWIP_EXIST_IN_SNAME_FILE [RFC 2242]
4 NWIP_EXIST_BUT_TOO_BIG [RFC 2242]
5 NSQ_BROADCAST [RFC 2242]
6 PREFERRED_DSS [RFC 2242]
7 NEAREST_NWIP_SERVER [RFC 2242]
8 AUTORETRIES [RFC 2242]
9 AUTORETRY_SECS [RFC 2242]
10 NWIP_1_1 [RFC 2242]
11 PRIMARY_DSS [RFC 2242]
12-255 Unassigned

DHCP Cablelabs Client Configuration Option Type 122 Sub-Option Codes

Registration Procedure(s)
IETF Review
Reference
[RFC 3495]
Available Formats

CSV
Code Sub-Option Description Reference
1 TSP's Primary DHCP Server Address [RFC 3495]
2 TSP's Secondary DHCP Server Address [RFC 3495]
3 TSP's Provisioning Server Address [RFC 3495]
4 TSP's AS-REQ/AS-REP Backoff and Retry [RFC 3495]
5 TSP's AP-REQ/AP-REP Backoff and Retry [RFC 3495]
6 TSP's Kerberos Realm Name [RFC 3495]
7 TSP's Ticket Granting Server Utilization [RFC 3495]
8 TSP's Provisioning Timer Value [RFC 3495]
9 TSP's Security Ticket Control [RFC 3594]
10 KDC Server Address [RFC 3634]
11-255 Unassigned

DHCP Status Code Type 151 Values

Registration Procedure(s)
IETF Review
Reference
[RFC 6926]
Available Formats

CSV
Status-Code Name Reference
0 Success [RFC 6926]
1 UnspecFail [RFC 6926]
2 QueryTerminated [RFC 6926]
3 MalformedQuery [RFC 6926]
4 NotAllowed [RFC 6926]
5 DataMissing [RFC 7724]
6 ConnectionActive [RFC 7724]
7 CatchUpComplete [RFC 7724]
8 TLSConnectionRefused [RFC 7724]
9-255 Unassigned

DHCP State Type 156 Values

Registration Procedure(s)
IETF Review
Reference
[RFC 6926]
Available Formats

CSV
State Name Reference
0 Reserved [RFC 6926]
1 AVAILABLE [RFC 6926]
2 ACTIVE [RFC 6926]
3 EXPIRED [RFC 6926]
4 RELEASED [RFC 6926]
5 ABANDONED [RFC 6926]
6 RESET [RFC 6926]
7 REMOTE [RFC 6926]
8 TRANSITIONING [RFC 6926]
9-255 Unassigned

Altitude Type Registry

Registration Procedure(s)
Standards Action
Reference
[RFC 6225]
Available Formats

CSV
Type Altitude Field Description Reference
0 No known altitude [RFC 6225]
1 Altitude in meters [RFC 6225]
2 Altitude in floors [RFC 6225]
3-15 Unassigned

Datum Registry

Registration Procedure(s)
Standards Action
Reference
[RFC 6225]
Available Formats

CSV
Datum Datum Field Description Reference
0 Reserved [RFC 6225]
1 Vertical datum WGS 84 defined by EPSG CRS Code 4327 [RFC 6225]
2 Vertical datum NAD83 defined by EPSG CRS Code 4269 with North American Vertical Datum of 1988 (NAVD88) [RFC 6225]
3 Vertical datum NAD83 defined by EPSG CRS Code 4269 with Mean Lower Low Water (MLLW) as associated vertical datum [RFC 6225]
4-7 Unassigned

GeoLoc Option Version Registry

Registration Procedure(s)
Standards Action
Reference
[RFC 6225]
Available Formats

CSV
Version Description Reference
0 Reserved [RFC 6225]
1 Implementations utilizing uncertainty parameters for both DHCPv4 and DHCPv6 GeoLoc options [RFC 6225]
2-3 Unassigned

CableLabs Client Configuration Option Ticket Control Mask Bit Definitions

Registration Procedure(s)
IETF Review
Reference
[RFC 3594]
Available Formats

CSV
Bit Description Reference
0 the PacketCable Provisioning Server used by the CCD. [RFC 3594]
1 the group of all PacketCable Call Management Servers used by the CCD. [RFC 3594]
2-15 Reserved and MUST be set to 0.

DHCP Relay Agent Sub-Option Codes

Registration Procedure(s)
IETF Review
Reference
[RFC 3046]
Available Formats

CSV
Code Sub-Option Description Reference
1 Agent Circuit ID Sub-option [RFC 3046]
2 Agent Remote ID Sub-option [RFC 3046]
3 Sub-option 3 is reserved and should not be assigned at this time; proprietary and incompatible usages of this sub-option value have been seen limited deployment. [Ralph_Droms]
4 DOCSIS Device Class Suboption [RFC 3256]
5 Link selection Sub-option [RFC 3527]
6 Subscriber-ID Suboption [RFC 3993]
7 RADIUS Attributes Sub-option [RFC 4014]
8 Authentication Suboption [RFC 4030]
9 Vendor-Specific Information Suboption [RFC 4243]
10 Relay Agent Flags [RFC 5010]
11 Server Identifier Override Suboption [RFC 5107]
12 Relay Agent Identifier Sub-option [RFC 6925]
13 Access-Technology-Type Sub-option [RFC 7839]
14 Access-Network-Name Sub-option [RFC 7839]
15 Access-Point-Name Sub-option [RFC 7839]
16 Access-Point-BSSID Sub-option [RFC 7839]
17 Operator-Identifier Sub-option [RFC 7839]
18 Operator-Realm Sub-option [RFC 7839]
19 DHCPv4 Relay Source Port Sub-Option [RFC 8357]
20-150 Unassigned
151 DHCPv4 Virtual Subnet Selection Sub-Option [RFC 6607]
152 DHCPv4 Virtual Subnet Selection Control Sub-Option [RFC 6607]

Authentication Suboption (value 8) - Protocol identifier values

Registration Procedure(s)
IETF Review
Reference
[RFC 3118]
Available Formats

CSV
Value Protocol Reference
0 DHCPv4 Configuration Token [RFC3118, Section 4]
1 DHCPv4 Delayed Authentication [RFC3118, Section 5]
2 DHCPv6 Delayed Authentication (Obsolete) [RFC 9915]
3 DHCPv6 Reconfigure Key Authentication [RFC 9915]
4-254 Unassigned
255 Reserved [RFC 3118]

Authentication Suboption (value 8) - Algorithm identifier values

Registration Procedure(s)
IETF Review
Reference
[RFC 4030]
Available Formats

CSV
Value Algorithm Reference
0 Reserved [RFC 4030]
1 HMAC-SHA1 keyed hash [RFC 4030]

Authentication Suboption (value 8) - Replay Detection Method (RDM) identifier values

Registration Procedure(s)
IETF Review
Reference
[RFC 4030]
Available Formats

CSV
Value Description Reference
0 Reserved [RFC 4030]
1 use of a monotonically increasing counter value [RFC 4030]

IEEE 802.21 Service Type (MoS DHCPv4 Address and FQDN Sub-Options)

Registration Procedure(s)
Standards Action
Reference
[RFC 5678]
Available Formats

CSV
Value Name Reference
0 Reserved [RFC 5678]
1 IS [RFC 5678]
2 CS [RFC 5678]
3 ES [RFC 5678]
4-254 Unassigned
255 Reserved [RFC 5678]

NTP Time Source Suboptions

Registration Procedure(s)
IETF Review
Reference
[RFC 5908]
Note
See the NTP Time Source Suboptions registry at [https://www.iana.org/assignments/dhcpv6-parameters]

VSS Type Options

Registration Procedure(s)
IETF Review
Reference
[RFC 6607]
Available Formats

CSV
Type Name Reference
0 Network Virtual Terminal (NVT) ASCII VPN identifier [RFC 6607]
1 RFC2685 VPN-ID [RFC 2685][RFC 6607]
2-253 Unassigned
254 All VPNs (wildcard) [RFC 6926]
255 Global, default VPN [RFC 6607]

RADIUS Attributes Permitted in RADIUS Attributes DHCP Suboption

Registration Procedure(s)
Expert Review
Expert(s)
Alan DeKok, Mohamed Boucadair
Reference
[RFC 9445]
Available Formats

CSV
Type Code Attribute Reference
1 User-Name [RFC 2865]
6 Service-Type [RFC 2865]
26 Vendor-Specific [RFC 2865]
27 Session-Timeout [RFC 2865]
88 Framed-Pool [RFC 2869]
100 Framed-IPv6-Pool [RFC 3162]
245.4 DHCPv4-Options [RFC 9445]

DHCP Options Permitted in the RADIUS DHCPv4-Options Attribute

Registration Procedure(s)
Expert Review
Expert(s)
Alan DeKok, Mohamed Boucadair
Reference
[RFC 9445]
Available Formats

CSV
Tag Name Reference
162 OPTION_V4_DNR [RFC 9445]

Contact Information

ID Name Contact URI Last Updated
[Ralph_Droms] Ralph Droms mailto:rdroms&cisco.com 2001-01