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ec(4) [bsd man page]

EC(4)							     Kernel Interfaces Manual							     EC(4)

NAME
ec - 3Com 10 Mb/s Ethernet interface SYNOPSIS
/sys/conf/SYSTEM: NEC ec_controllers # 3Com Ethernet DESCRIPTION
The ec interface provides access to a 10 Mb/s Ethernet network through a 3com controller. The hardware has 32 kilobytes of dual-ported memory on the UNIBUS. This memory is used for internal buffering by the board, and the inter- face code reads the buffer contents directly through the UNIBUS. The address of this memory is given in the flags field in the configura- tion file. The first interface normally has its memory at Unibus address 0. Each of the host's network addresses is specified at boot time with an SIOCSIFADDR ioctl. The ec interface employs the address resolution protocol described in arp(4P) to dynamically map between Internet and Ethernet addresses on the local network. The interface normally tries to use a ``trailer'' encapsulation to minimize copying data on input and output. The use of trailers is nego- tiated with ARP. This negotiation may be disabled, on a per-interface basis, by setting the IFF_NOTRAILERS flag with an SIOCSIFFLAGS ioctl. The interface software implements an exponential backoff algorithm when notified of a collision on the cable. This algorithm utilizes a 16-bit mask and the VAX-11's interval timer in calculating a series of random backoff values. The algorithm is as follows: 1. Initialize the mask to be all 1's. 2. If the mask is zero, 16 retries have been made and we give up. 3. Shift the mask left one bit and formulate a backoff by masking the interval timer with the smaller of the complement of this mask and a 5-bit mask, resulting in a pseudo-random number between 0 and 31. This produces the number of slot times to delay, where a slot is 51 microseconds. 4. Use the value calculated in step 3 to delay before retransmitting the packet. The delay is done in a software busy loop. DIAGNOSTICS
ec%d: send error. After 16 retransmissions using the exponential backoff algorithm described above, the packet was dropped. ec%d: input error (offset=%d). The hardware indicated an error in reading a packet off the cable or an illegally sized packet. The buffer offset value is printed for debugging purposes. ec%d: can't handle af%d. The interface was handed a message with addresses formatted in an unsuitable address family; the packet was dropped. SEE ALSO
intro(4N), inet(4F), arp(4P) BUGS
The hardware is not capable of talking to itself. The software implements local sending and broadcast by sending such packets to the loop interface. This is a kludge. Backoff delays are done in a software busy loop. This can degrade the system if the network experiences frequent collisions. 3rd Berkeley Distribution August 20, 1987 EC(4)

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ln(4)							     Kernel Interfaces Manual							     ln(4)

Name
       ln - Lance Ethernet interface

Syntax
       device ln0 at ibus? vector lnintr

Description
       The interface provides access to a 10 Mb/s Ethernet network through the Lance controller.

       The  host's  Internet  address  is specified at boot time with an SIOCSIFADDR ioctl.  The interface employs the address resolution protocol
       described in to map dynamically between Internet and Ethernet addresses on the local network.

       The interface normally tries to use a trailer encapsulation to minimize copying data on input and output.  This	can  be  disabled  for	an
       interface by setting the IFF_NOTRAILERS flag with an SIOCSIFFLAGS ioctl.  Trailers are only used for packets destined for Internet hosts.

       The  SIOCSPHYSADDR ioctl can be used to change the physical address of the Lance.  The SIOCRPHYSADDR ioctl can be used to read the physical
       address of the Lance.

       The SIOCADDMULTI and SIOCDELMULTI ioctls can be used to add or delete multicast addresses.  The Lance recognizes a maximum of 12  multicast
       addresses.

       The  SIOCRDCTRS	and  SIOCRDZCTRS ioctls can be used to read or ``read and clear'' the Ethernet driver counters.  The argument to these two
       ioctls is a pointer to a counter structure, found in

       The SIOCENABLBACK and SIOCDISABLBACK ioctls can be used to enable and disable the interface loopback mode respectively.

Diagnostics
       The diagnostic error messages contain relevant information provided by the Lance.

       ln%d: can't handle af%d
       The interface was handed a message with addresses formated in an unsuitable address family, and the packet was dropped.

       ln%d: memory error (MERR)
       A memory parity error has occurred.

       ln%d: lnalloc: cannot alloc memory ...
       The driver was unable to allocate memory for internal data structures.

       ln%d: initialization error
       The driver was unable to initialize the network interface.

       ln%d: SIOCADDMULTI fail, multicast list full
       Too many multicast requests have been made.

See Also
       arp(4p), inet(4f), intro(4n)

																	     ln(4)

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