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Router 7200 accept crc4 config but does not show it on show interface


Hi guys, I have a Router 7200  with this version "IOS (tm) 7200 Software (C7200-JK9S-M), Version 12.2(21a), RELEASE SOFTWARE (fc2)". I need to configure the serial 4/0 like "no crc4" or "crc4". When i configure crc4  it takes the changes but does not show it on show inter serial "4/0", it still show crc16 that is the  default value. On the second case i configure crc 32 and the router show the change but when i put "no crc" it returns to default "crc16". I reviewed the documentation about this router and says that if i put "crc4" should take it. Could you help me with this???

RPCA_MT_601(config)#interface Serial4/0



RPCA_MT_601#show inter Serial4/0

Serial4/0 is up, line protocol is down

  Hardware is 4ME1-UNBAL

  Description: Ruta IVR SCR-CCS  Trail ID 20462 XDM CAN2 I5-01 XDM MSCR I3-43

  Internet address is

  MTU 1500 bytes, BW 2048 Kbit, DLY 20000 usec,

     reliability 128/255, txload 1/255, rxload 1/255

  Encapsulation HDLC, crc 16, loopback not set

  Keepalive set (10 sec)

  Restart-Delay is 0 secs

3 Replies 3

paolo bevilacqua
Hall of Fame
Hall of Fame

There is no such thing as CRC4 for HDLC circuits. So if the router "takes" it, is a bug.

if  i put ppp encapsulation then it would accepts the crc4? in a router 7200 with the version that i mention before i could configure the serial interface like unframe (framing no-crc4)? how can i do this? because whe i put no crc  it returns tu the default crc16. How can i disable the crc feature in a 7200??

Again: CRC4 is only for E1 controller level, not serial interface, no matter encapsulation type.

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