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4200G Network Connectivity

BenjaminOwen
Occasional Contributor

4200G Network Connectivity

I am have recently replaced two 3COM Superstack 3 4924 switches(End Of Life) with two 3COM 4200G switches which are connected to one another. I am new to the 3COM CLI but I am familiar with Cisco. I am using the factory default configuration where everything is connected to the default VLAN. I am experiencing a network reliability issue where it seems that the switches are not sharing information between one another. See example below. I have tried several things such as enabling NDP, and upgrading the IOS. I have also tried using Knoppix in the all the machines to keep the network configuration simple. Does anyone have any ideas as to why I might be experiencing this problem.



Example



Switch X (192.168.231.41) is connected to Switch Y (192.168.231.42)

Machine A (192.168.231.80) is connected to Switch X

Machine B (192.168.231.125) is connected to Switch X

Machine C (192.168.231.122) is connected to Switch X

Machine M (192.168.231.61) is connected to Switch Y

Machine N (192.168.231.62) is connected to Switch Y



Machine A can ping Machine M but cannot ping Machine N

Machine B can ping Machine N but cannot ping Machine M

Machine C can ping Machine A, Machine B, Machine M, and Machine N

Machine M can ping Machine A but cannot ping Machine B

Machine N can ping Machine B but cannot ping Machine A



2 REPLIES
wolfgangB
Occasional Advisor

Re: 4200G Network Connectivity

Very strange. Usually they work out-of-the-box, with no configuration necessary.

I'd check this:

1. (web GUI) check the link status of all observed ports - sometimes auto-negotiation doesn't succeed (on the host side, that is); speed advertised, speed negotiated, half/full duplex mode, both on the switch and the host NIC.

2. (CLI) check if auto-VLAN has kicked in 'display vlan dynamic', 'display vlan all'. All host should be able to ping the switch (mgmt interface) they are connected to.

3. check the link between the switches; start with 1 single link. No config needed.

4. at last, check the MAC address table on each switch, to see if all hosts are seen by the switch ('dis arp dy'). To populate, let each host ping some target. Do you see MACs on the hosts 'arp -a'?



Keep us posted.



w-b

BenjaminOwen
Occasional Contributor

Re: 4200G Network Connectivity

Thanks for your replay. I tried the few things that you had suggested.



1. (web GUI) check the link status of all observed ports - sometimes auto-negotiation doesn't succeed (on the host side, that is); speed advertised, speed negotiated, half/full duplex mode, both on the switch and the host NIC.



I checked the link status of all observed ports on the switch and on the host. All ports had speed=1000M and duplex=full.





2. (CLI) check if auto-VLAN has kicked in 'display vlan dynamic', 'display vlan all'. All host should be able to ping the switch (mgmt interface) they are connected to.





After typing ‘display vlan dynamic’, I received ‘no dynamic vlans exists’ message





After typing ‘display vlan all’, output displayed all ports on VLAN1 untagged.





3. check the link between the switches; start with 1 single link. No config needed.



I checked the link between the switches, and they were able to ping each other. I also check the speed(1000M) and duplex(Full).





4. at last, check the MAC address table on each switch, to see if all hosts are seen by the switch ('dis arp dy'). To populate, let each host ping some target. Do you see MACs on the hosts 'arp -a'?





I performed the ‘display arp dynamic’ and found that all MAC addresses were listed in both switches. I noticed that Switch B could ping everything that was connected to it and everything that was connected to Switch A.



Switch A was able to ping everything connected to it but was not able to ping most of the things that were connected to Switch B even though Switch A knew where these machines were. (Arp Table).





Thanks

Ben