Como posso saber se a compactação PPP está habilitada para modem?

Question

Estou usando o Debian Linux em um sistema embarcado, usamos ppp para conectar a WAN através de um modem CDMA. Desejo descobrir se a compactação está sendo usada por ppp .

No meu /var/log/messages , vejo a linha:

kernel: [   54.740000] PPP Deflate Compression module registered

mas em /var/log/debug eu vejo isto:

pppd[2433]: Protocol-Reject for 'Compression Control Protocol' (0x80fd) received

A saída de pppstats -z é:

IN:  COMPRESSED  INCOMPRESSIBLE   COMP | OUT: COMPRESSED  INCOMPRESSIBLE   COMP
    BYTE   PACK     BYTE   PACK  RATIO |     BYTE   PACK     BYTE   PACK  RATIO
       0      0        0      0   0.00 |        0      0        0      0   0.00

O mesmo acontece com a compressão média acima, ou não?

    

Answer 1

Você pode usar o comando pppstats -z para exibir as estatísticas de compactação. Se ele exibir todos os zeros, a compactação não será ativada.

trecho da página man

   -z     Instead of the standard display, show statistics indicating the 
          performance of the packet compression algorithm in use.

   When the -z option is specified, instead displays the following fields,
   relating to the packet compression algorithm currently in use.   If
   packet compression is not in use, these fields will all display zeroes.  
   The fields displayed on the input side are:

   COMPRESSED BYTE
          The number of bytes of compressed packets received.

   COMPRESSED PACK
          The number of compressed packets received.

   INCOMPRESSIBLE BYTE
          The number of bytes of incompressible packets (that is, those 
          which were transmitted in uncompressed form) received.

   INCOMPRESSIBLE PACK
          The number of incompressible packets received.

   COMP RATIO
          The  recent  compression ratio for incoming packets, defined as 
          the uncompressed size divided by the compressed size (including 
          both compressible and incompressible packets).

   The fields displayed on the output side are:

   COMPRESSED BYTE
          The number of bytes of compressed packets transmitted.

   COMPRESSED PACK
          The number of compressed packets transmitted.

   INCOMPRESSIBLE BYTE
          The number of bytes of incompressible packets transmitted (that 
          is, those which were transmitted in uncompressed form).

   INCOMPRESSIBLE PACK
          The number of incompressible packets transmitted.

   COMP RATIO
          The recent compression ratio for outgoing packets.

    

Answer 2

Verifique /etc/ppp/options .

NÃO edite esse arquivo, copie-o para algum local e edite.

verifique isso:

# Disable Address/Control compression negotiation (use default, i.e.
# address/control field disabled).
#-ac

Mais informações podem ser encontradas no PPP-HOWTO .