Is ff:00:00:00:00:00 a broadcast frame?

From: Dax Kelson (dax@GuruLabs.com)
Date: Mon Jul 01 2002 - 18:27:11 EST

In the "earlier" 2.4 kernels (those that shipped/errata with RHL 7.1
~2.4.6), an ethernet frame destined to ff:00:00:00:00:00 were not
processed and passed up the stack.

Now, with "current" 2.4 kernels (RHL 7.2 errata, and RHL 7.3
2.4.9-2.4.18), the same frame IS processed and passed up the stack.

The hardware is identical, the NICs are 3c905C.

Is this an intentional optimization/bug?

Here is an ARP request encapsulated in a "bogus" ethernet frame (look at
the layer 2 destination). A RHL 7.3 (2.4.18) system will respond (see
Frame 2 below) to this frame, an older RHL 7.1 (2.4.6) system will not
respond.

Frame 1 (42 on wire, 42 captured)
    Arrival Time: Jul 1, 2002 17:16:35.565996000
    Time delta from previous packet: 1.009672000 seconds
    Time relative to first packet: 1.009833000 seconds
    Frame Number: 3
    Packet Length: 42 bytes
    Capture Length: 42 bytes
Ethernet II
    Destination: ff:00:00:00:00:00 (ff:00:00:00:00:00)
    Source: ff:00:00:00:00:00 (ff:00:00:00:00:00)
    Type: ARP (0x0806)
Address Resolution Protocol (request)
    Hardware type: Ethernet (0x0001)
    Protocol type: IP (0x0800)
    Hardware size: 6
    Protocol size: 4
    Opcode: request (0x0001)
    Sender MAC address: 00:01:03:de:56:a4 (00:01:03:de:56:a4)
    Sender IP address: 10.100.0.8 (10.100.0.8)
    Target MAC address: 00:00:00:00:00:00 (00:00:00:00:00:00)
    Target IP address: 10.100.0.10 (10.100.0.10)

Frame 2 (60 on wire, 60 captured)
    Arrival Time: Jul 1, 2002 17:16:35.566146000
    Time delta from previous packet: 0.000150000 seconds
    Time relative to first packet: 1.009983000 seconds
    Frame Number: 4
    Packet Length: 60 bytes
    Capture Length: 60 bytes
Ethernet II
    Destination: 00:01:03:de:56:a4 (00:01:03:de:56:a4)
    Source: 00:01:03:de:57:37 (00:01:03:de:57:37)
    Type: ARP (0x0806)
    Trailer: 00000000000000000000000000000000...
Address Resolution Protocol (reply)
    Hardware type: Ethernet (0x0001)
    Protocol type: IP (0x0800)
    Hardware size: 6
    Protocol size: 4
    Opcode: reply (0x0002)
    Sender MAC address: 00:01:03:de:57:37 (00:01:03:de:57:37)
    Sender IP address: 10.100.0.10 (10.100.0.10)
    Target MAC address: 00:01:03:de:56:a4 (00:01:03:de:56:a4)
    Target IP address: 10.100.0.8 (10.100.0.8)

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This archive was generated by hypermail 2b29 : Sun Jul 07 2002 - 22:00:08 EST