* The mrouted program is covered by the license in the accompanying file
* named "LICENSE". Use of the mrouted program represents acceptance of
* the terms and conditions listed in that file.
* The mrouted program is COPYRIGHT 1989 by The Board of Trustees of
* Leland Stanford Junior University.
* $Id: dvmrp.h,v 1.3 1993/05/30 01:36:38 deering Exp $
* A DVMRP message consists of an IP header + an IGMP header + (for some types)
* zero or more bytes of data.
* For REPORT messages, the data is route information; the route information
* consists of one or more lists of the following form:
* (mask, (origin, metric), (origin, metric), ...)
* "mask" is the subnet mask for all the origins in the list.
* It is always THREE bytes long, containing the low-order
* three bytes of the mask (the high-order byte is always
* 0xff and therefore need not be transmitted).
* "origin" is the number of a subnet from which multicast datagrams
* may originate. It is from one to four bytes long,
* depending on the value of "mask":
* if all bytes of the mask are zero
* the subnet number is one byte long
* else if the low-order two bytes of the mask are zero
* the subnet number is two bytes long
* else if the lowest-order byte of the mask is zero
* the subnet number is three bytes long,
* the subnet number is four bytes long.
* "metric" is a one-byte value consisting of two subfields:
* - the high-order bit is a flag which, when set, indicates
* the last (origin, metric) pair of a list.
* - the low-order seven bits contain the routing metric for
* the corresponding origin, relative to the sender of the
* DVMRP report. The metric may have the value of UNREACHABLE
* added to it as a "split horizon" indication (so called
* Within a list, the origin subnet numbers must be in ascending order, and
* the lists themselves are in order of increasing mask value. A message may
* not exceed 576 bytes, the default maximum IP reassembly size, including
* the IP and IGMP headers; the route information may be split across more
* than one message if necessary, by terminating a list in one message and
* starting a new list in the next message (repeating the same mask value,
* For NEIGHBORS messages, the data is neighboring-router information
* consisting of one or more lists of the following form:
* (local-addr, metric, threshold, ncount, neighbor, neighbor, ...)
* "local-addr" is the sending router's address as seen by the neighbors
* in this list; it is always four bytes long.
* "metric" is a one-byte unsigned value, the TTL `cost' of forwarding
* packets to any of the neighbors on this list.
* "threshold" is a one-byte unsigned value, a lower bound on the TTL a
* packet must have to be forwarded to any of the neighbors on
* "ncount" is the number of neighbors in this list.
* "neighbor" is the address of a neighboring router, four bytes long.
* As with REPORT messages, NEIGHBORS messages should not exceed 576 bytes,
* including the IP and IGMP headers; split longer messages by terminating the
* list in one and continuing in another, repeating the local-addr, etc., if
* For NEIGHBORS2 messages, the data is identical to NEIGHBORS except
* there is a flags byte before the neighbor count:
* (local-addr, metric, threshold, flags, ncount, neighbor, neighbor, ...)
* DVMRP message types (carried in the "code" field of an IGMP header)
#define DVMRP_PROBE 1 /* for finding neighbors */
#define DVMRP_REPORT 2 /* for reporting some or all routes */
#define DVMRP_ASK_NEIGHBORS 3 /* sent by mapper, asking for a list */
/* of this router's neighbors. */
#define DVMRP_NEIGHBORS 4 /* response to such a request */
#define DVMRP_ASK_NEIGHBORS2 5 /* as above, want new format reply */
#define DVMRP_NEIGHBORS2 6
* 'flags' byte values in DVMRP_NEIGHBORS2 reply.
#define DVMRP_NF_TUNNEL 0x01 /* neighbors reached via tunnel */
#define DVMRP_NF_SRCRT 0x02 /* tunnel uses IP source routing */
#define DVMRP_NF_DOWN 0x10 /* kernel state of interface */
#define DVMRP_NF_DISABLED 0x20 /* administratively disabled */
#define DVMRP_NF_QUERIER 0x40 /* I am the subnet's querier */
* Limit on length of route data
#define MAX_IP_PACKET_LEN 576
#define MIN_IP_HEADER_LEN 20
#define MAX_IP_HEADER_LEN 60
#define MAX_DVMRP_DATA_LEN \
( MAX_IP_PACKET_LEN - MAX_IP_HEADER_LEN - IGMP_MINLEN )
* Various protocol constants (all times in seconds)
/* address for multicast DVMRP msgs */
#define INADDR_DVMRP_GROUP (u_long)0xe0000004 /* 224.0.0.4 */
#define ROUTE_MAX_REPORT_DELAY 5 /* max delay for reporting changes */
/* (This is the timer interrupt */
/* interval; all times must be */
/* multiples of this value.) */
#define ROUTE_REPORT_INTERVAL 60 /* periodic route report interval */
#define ROUTE_SWITCH_TIME 140 /* time to switch to equivalent gw */
#define ROUTE_EXPIRE_TIME 200 /* time to mark route invalid */
#define ROUTE_DISCARD_TIME 340 /* time to garbage collect route */
#define LEAF_CONFIRMATION_TIME 200 /* time to consider subnet a leaf */
#define NEIGHBOR_PROBE_INTERVAL 190 /* periodic neighbor probe interval */
#define NEIGHBOR_EXPIRE_TIME 140 /* time to consider neighbor gone */
#define GROUP_QUERY_INTERVAL 125 /* periodic group query interval */
#define GROUP_EXPIRE_TIME 270 /* time to consider group gone */
#define UNREACHABLE 32 /* "infinity" metric, must be <= 64 */
#define DEFAULT_METRIC 1 /* default subnet/tunnel metric */
#define DEFAULT_THRESHOLD 1 /* default subnet/tunnel threshold */
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