[c-nsp] Interface byte counters

[Rodney Dunn]

I sent 1 packet of 100 byte ping:

Frame 1 (118 bytes on wire, 118 bytes captured) 
    Arrival Time: Dec 31, 1969 16:00:00.000000000 
    Time delta from previous packet: 0.000000000 seconds 
    Time since reference or first frame: 0.000000000 seconds 
    Frame Number: 1 
    Packet Length: 118 bytes 
    Capture Length: 118 bytes 
Ethernet II, Src: aa:bb:cc:00:64:00, Dst: aa:bb:cc:00:65:00 
    Destination: aa:bb:cc:00:65:00 (aa:bb:cc:00:65:00) 
    Source: aa:bb:cc:00:64:00 (aa:bb:cc:00:64:00) 
    Type: IP (0x0800) 
    Frame check sequence: 0x00000000 (incorrect, should be 0x7c4a12af) 
Internet Protocol, Src Addr: 1.1.1.1 (1.1.1.1), Dst Addr: 1.1.1.2 (1.1.1.2) 
    Version: 4 
    Header length: 20 bytes 
    Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00) 
        0000 00.. = Differentiated Services Codepoint: Default (0x00) 
        .... ..0. = ECN-Capable Transport (ECT): 0 
        .... ...0 = ECN-CE: 0 
    Total Length: 100 
    Identification: 0x0017 (23) 
    Flags: 0x00 
        0... = Reserved bit: Not set 
        .0.. = Don't fragment: Not set 
        ..0. = More fragments: Not set 
    Fragment offset: 0 
    Time to live: 254 
    Protocol: ICMP (0x01) 
    Header checksum: 0xb87d (correct) 
    Source: 1.1.1.1 (1.1.1.1) 
    Destination: 1.1.1.2 (1.1.1.2) 
Internet Control Message Protocol 
    Type: 8 (Echo (ping) request) 
    Code: 0  
    Checksum: 0xdfde (correct) 
    Identifier: 0x000b 
    Sequence number: 0x0000 
    Data (72 bytes) 
 
0000  00 00 00 00 05 10 99 50 ab cd ab cd ab cd ab cd   .......P........ 
0010  ab cd ab cd ab cd ab cd ab cd ab cd ab cd ab cd   ................ 
0020  ab cd ab cd ab cd ab cd ab cd ab cd ab cd ab cd   ................ 
0030  ab cd ab cd ab cd ab cd ab cd ab cd ab cd ab cd   ................ 
0040  ab cd ab cd ab cd ab cd                           ........ 

and the interface showed:

101_#sh int e0/0 | incl packets in
     1 packets input, 114 bytes, 0 no buffer

So that's 72 bytes of data + 8 bytes of ICMP +
20 bytes of IP + 12 bytes of MAC + 2 bytes TYPE = 114
so I'd say the answer is no the FCS isn't included.

Rodney

On Fri, Sep 03, 2004 at 10:30:39AM -0600, Clinton Work wrote:
> According to Cisco documentation the interface byte counters include the MAC
> encapsulation. Does
> this include the 4-byte FCS for ethernet II?
> 
> router#show int fa0 | inc input|output
>   Last input 00:00:03, output 00:00:00, output hang never
>   Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
>   5 minute input rate 64000 bits/sec, 113 packets/sec
>   5 minute output rate 138000 bits/sec, 84 packets/sec
>      8749777 packets input, 603929443 bytes
>      0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
>      0 input packets with dribble condition detected
>      6308549 packets output, 2950512478 bytes, 0 underruns
>      0 output errors, 0 collisions, 4 interface resets
>      0 output buffer failures, 0 output buffers swapped out
> 
> 
> 
> =========================================================================
> Clinton Work                                        clinton at scripty.com
> Calgary, Alberta
> 
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