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Cisco 837 Configuration problems ?

I am have intermittent connection problems connecting to a web site using a Cisco 837 router. I have

no such problems with my Speedtouch modem.

The following two traces from CBAC on a Cisco 837 Router are from identical requests. (The errstr's

actually copied from the L4 inspection output)

Request that failed:

Pak 812754E0 IP: s=L.L.L.L (Ethernet0), d=R.R.R.R (Dialer0), len 62, proto=6

sis 81679C18 pak 812754E0 SIS_CLOSED/LISTEN TCP SYN SEQ 1996618461 LEN 0

Pak 813AE6E4 IP: s=R.R.R.R (Dialer0), d=192.168.0.3 (Ethernet0), len 46, proto=6

sis 81679C18 pak 813AE6E4 SIS_OPENING/SYNSENT TCP SYN ACK 1996618462 SEQ 2732661948 LEN 0

Pak 813ED334 IP: s=L.L.L.L (Ethernet0), d=R.R.R.R (Dialer0), len 60, proto=6

sis 81679C18 pak 813ED334 SIS_OPENING/SYNRCVD TCP ACK 2732661949 SEQ 1996618462 LEN 0

Pak 813EEEA0 IP: s=L.L.L.L (Ethernet0), d=R.R.R.R (Dialer0), len 94, proto=6

sis 81679C18 pak 813EEEA0 SIS_OPEN/ESTAB TCP PSH ACK 2732661949 SEQ 1996618462 LEN 40

Pak 813AECFC IP: s=R.R.R.R (Dialer0), d=192.168.0.3 (Ethernet0), len 42, proto=6

sis 81679C18 pak 813AECFC SIS_OPEN/ESTAB TCP ACK 1996618502 SEQ 2732661949 LEN 0

Pak 813B0B74 IP: s=R.R.R.R (Dialer0), d=192.168.0.3 (Ethernet0), len 42, proto=6

sis 81679C18 pak 813B0B74 SIS_OPEN/ESTAB TCP FIN ACK 1996618502 SEQ 2732662397 LEN 0 bytes 0 ErrStr = Out-Of-Order Segment tcp

Pak 813ADDC0 IP: s=R.R.R.R (Dialer0), d=192.168.0.3 (Ethernet0), len 538, proto=6

sis 81679C18 pak 813ADDC0 SIS_OPEN/CLOSEWAIT TCP PSH ACK 1996618502 SEQ 2732661949 LEN 496 bytes 47 ErrStr = Invalid Segment tcp

Pak 813AE3D8 IP: s=R.R.R.R (Dialer0), d=192.168.0.3 (Ethernet0), len 538, proto=6

sis 81679C18 pak 813AE3D8 SIS_OPEN/CLOSEWAIT TCP FIN PSH ACK 1996618502 SEQ 2732661949 LEN 496 bytes 47 ErrStr = Invalid Segment tcp

Pak 813ADAB4 IP: s=R.R.R.R (Dialer0), d=192.168.0.3 (Ethernet0), len 42, proto=6

sis 81679C18 pak 813ADAB4 SIS_OPEN/CLOSEWAIT TCP RST SEQ 2732661949 LEN 0

Request that succeeded:

Pak 8156CAF4 IP: s=L.L.L.L (Ethernet0), d=R.R.R.R (Dialer0), len 62, proto=6

sis 81679288 pak 8156CAF4 SIS_CLOSED/LISTEN TCP SYN SEQ 3584172415 LEN 0

Pak 813B0868 IP: s=R.R.R.R (Dialer0), d=192.168.0.3 (Ethernet0), len 46, proto=6

sis 81679288 pak 813B0868 SIS_OPENING/SYNSENT TCP SYN ACK 3584172416 SEQ 2732766006 LEN 0

Pak 813ED640 IP: s=L.L.L.L (Ethernet0), d=R.R.R.R (Dialer0), len 60, proto=6

sis 81679288 pak 813ED640 SIS_OPENING/SYNRCVD TCP ACK 2732766007 SEQ 3584172416 LEN 0

Pak 813EF1AC IP: s=L.L.L.L (Ethernet0), d=R.R.R.R (Dialer0), len 94, proto=6

sis 81679288 pak 813EF1AC SIS_OPEN/ESTAB TCP PSH ACK 2732766007 SEQ 3584172416 LEN 40

Pak 813AD7A8 IP: s=R.R.R.R (Dialer0), d=192.168.0.3 (Ethernet0), len 42, proto=6

sis 81679288 pak 813AD7A8 SIS_OPEN/ESTAB TCP ACK 3584172456 SEQ 2732766007 LEN 0

Pak 813AF008 IP: s=R.R.R.R (Dialer0), d=192.168.0.3 (Ethernet0), len 42, proto=6

sis 81679288 pak 813AF008 SIS_OPEN/ESTAB TCP FIN ACK 3584172456 SEQ 2732766503 LEN 0 bytes 0 ErrStr = Out-Of-Order Segment tcp

Pak 813B1498 IP: s=R.R.R.R (Dialer0), d=192.168.0.3 (Ethernet0), len 538, proto=6

sis 81679288 pak 813B1498 SIS_OPEN/CLOSEWAIT TCP PSH ACK 3584172456 SEQ 2732766007 LEN 496 bytes 496 ErrStr = Retransmitted Segment tcp

Pak 813EB1B0 IP: s=L.L.L.L (Ethernet0), d=R.R.R.R (Dialer0), len 60, proto=6

sis 81679288 pak 813EB1B0 SIS_OPEN/CLOSEWAIT TCP ACK 2732766504

Pak 813EEB94 IP: s=L.L.L.L (Ethernet0), d=R.R.R.R (Dialer0), len 60, proto=6

sis 81679288 pak 813EEB94 SIS_OPEN/CLOSEWAIT TCP FIN ACK 2732766504 SEQ 3584172456 LEN 0

The difference between the two is that although both packets have 496 bytes of data, in the first case

the SEQ goes from 2732661949 to 2732662397 ie 448, hence the invalid segment message.

496 - 448 = 48 the size of an ATM packet, or is that just a coincidence.

My question is do I have my router misconfigured?

1 REPLY
Silver

Re: Cisco 837 Configuration problems ?

As you are using the main interface for the PVC

configuration, do not forget to add the IP to ATM mapping for the remote

IP address under the PVC. This should be done like this:

interface ATM0

pvc 8/48

protocol ip broadcast

Finally, when using encryption and CBWFQ, you have to make sure

pre-classification is configured to make sure that CBWFQ classification

is applied before the packets are encrypted. Not doing this will cause

all packets to be place in the default-class.

The command is described at the following URL:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios123/123cgcr/qos_

r/qos_q1g.htm#wp1080229

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