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Recieve broadcast packets but not tcp packets.

Last response: in Networking
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September 13, 2006 2:21:01 PM

I connect to the net using ethernet. It was running fine couple of days back but i cannot ping my gateway. The status of the connection says connected but i cannot ping anyone. I installed ethereal and observed that i can recieve broadcast packets like osp, arp, stp etc but not a single tcp packet.

the technician from my isp came to my place today, he tested the cable in a cable tester which displayed that out of the 8 wires inside a lan cable, wires
2 - 8 wires were good but wire 1 was not. He said that he will have to change the ethernet cable which would take atleast 5 - 10 days.

Now i know that out of 8 wires only 4 wires are used in an ethernet lan. What i want to know is that can i swap the wire which is damaged with a wire which is not used. Will this work. Do we need all the 8 wires working properly for an ethernet lan to work


PC - Straight Cable- - Switch

Pin 1 TX+ -------------- Pin 1 RX+
Pin 2 TX- -------------- Pin 2 RX-
Pin 3 RX+ ------------- Pin 3 TX+
Pin 6 RX- ------------- Pin 6 TX-
September 13, 2006 7:12:04 PM

Buy a new cable... save yourself the trouble.
September 13, 2006 7:16:55 PM

More than likely there is a bad connection. Unless his tester indicated a break at a certain distance. Some of the newer MB's have the capability to test cables, through a utility.

I would re-terminate the ends.

Yes it is true only 4 wires are use in 10/100 speed. Since this is a 4 pair cable with each pair having a different twist/foot. Terminate using all 4 pair. Helps with capacitence and noise reduction.
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September 13, 2006 10:06:26 PM

If you run a sniffer in promiscuous mode and you see broadcast traffic but don't see any unicast traffic, that means you don't have an IP address and therefore you cannot ping anything or have any network connection.

Quote:
I connect to the net using ethernet. It was running fine couple of days back but i cannot ping my gateway. The status of the connection says connected but i cannot ping anyone. I installed ethereal and observed that i can recieve broadcast packets like osp, arp, stp etc but not a single tcp packet.

the technician from my isp came to my place today, he tested the cable in a cable tester which displayed that out of the 8 wires inside a lan cable, wires
2 - 8 wires were good but wire 1 was not. He said that he will have to change the ethernet cable which would take atleast 5 - 10 days.

Now i know that out of 8 wires only 4 wires are used in an ethernet lan. What i want to know is that can i swap the wire which is damaged with a wire which is not used. Will this work. Do we need all the 8 wires working properly for an ethernet lan to work


PC - Straight Cable- - Switch

Pin 1 TX+ -------------- Pin 1 RX+
Pin 2 TX- -------------- Pin 2 RX-
Pin 3 RX+ ------------- Pin 3 TX+
Pin 6 RX- ------------- Pin 6 TX-
September 14, 2006 4:12:06 AM

Since pin 1 is in your transmit pair, it's feasible that you cannot transmit but are still seeing broadcasts from the rest of the network because your receive pair is still functioning.

Exactly how long is this Ethernet cable that needs to be replaced? It shouldn't be more than a few feet, from your modem to your PC. Did he say why it was going to take 5-10 days to replace an Ethernet cable? Sounds like you need a new ISP. :-P
September 14, 2006 12:50:20 PM

Quote:

Exactly how long is this Ethernet cable that needs to be replaced? It shouldn't be more than a few feet, from your modem to your PC. Did he say why it was going to take 5-10 days to replace an Ethernet cable? Sounds like you need a new ISP. :-P



The wire is around 60 - 70 metres long from my pc to the switch. I cannot change my isp bcoz its a monopoly in my area.

I said it would take 5 - 10 days bcoz im in India. In India a consumer has no rights. We have to beg and bribe to get something done.

I cannot do it myself coz the switch is locked in a box. Only the isp's technician has the key.

Will call him tomorrow and see what happens.
!