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Problem Daisy-Chaining 2950 Using Copper Giga

Hi.

I am having weird problems when I connect together three Catalyst 2950 switches. I want to use the two gigaethernet interfaces on the middle switch to connect to two other 2950's using switchport mode trunk for VLAN support. Whenever I do this I see CRC errors on the gigaethernet ports (not a lot - about 1 error in 1000 packets). Also when I ping from a machine on one switch to a machine on another switch I see a few percent packet loss. It is not possible to sustain a remote desktop (terminal services) connection from one switch to another. In addition I see an extremely high number of input errors on the VLAN1 interface of the switches (for example -232203 packets input, 60958 input errors).

The cables I am using were manufactured by a very respected company, and I have swapped cables multiple times. I have also completely switched the middle switch. I have tried various combinations of speed and duplex. Nothing helps.

Any ideas, anyone ???

TIA.

Here is a slightly edited version of my configurations:

! version 12.1 no service pad service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname MiddleSwitch ! ! ip subnet-zero ! vtp mode transparent ! spanning-tree mode pvst no spanning-tree optimize bpdu transmission spanning-tree extend system-id ! ! ! ! vlan 2-3,11,301,901 ! interface FastEthernet0/1 switchport mode trunk speed 100 duplex full ! interface FastEthernet0/2 switchport mode trunk speed 100 duplex full ! interface FastEthernet0/3 switchport access vlan 3 spanning-tree portfast

interface GigabitEthernet0/1 switchport mode trunk ! interface GigabitEthernet0/2 switchport mode trunk load-interval 30 speed 1000 duplex full ! interface Vlan1 ip address 172.16.253.1 255.255.0.0 no ip route-cache ! ip default-gateway 172.16.0.1 ip http server ! ! end

===================================================================

version 12.1 no service pad service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname LowerSwitch ! ! ip subnet-zero ! vtp mode transparent ! spanning-tree mode pvst no spanning-tree optimize bpdu transmission spanning-tree extend system-id ! !

! Vlan 3 is for external IPs

vlan 3

! ! interface FastEthernet0/1 spanning-tree portfast speed 100 duplex full ! ! interface FastEthernet0/23 switchport access vlan 3 spanning-tree portfast speed 100 duplex full ! interface FastEthernet0/24 switchport access vlan 3 spanning-tree portfast speed 100 duplex full ! interface GigabitEthernet0/1 switchport mode trunk ! interface GigabitEthernet0/2 ! interface Vlan1 ip address 172.16.253.5 255.255.0.0 no ip route-cache ! ip http server !

Reply to
Aharon Schkolnik
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  1. What IOS version(s) are running on the 2950 switches, please post show version ffor each of the three switches.

  1. How have you cabled the switch ports together. Indicate switch # and port nos that are connected together.

Reply to
Merv

also post show interface for each of the giga port that are calbed together.

What are the colours of the giga port LEDS?

Reply to
Merv

Did you check the speed and duplex settings of the running ports. Not those of the config file, but the real status. My first thing to check would be to see whether one port came up in duplex and the other in half duplex or so.

Ahar> Hi.

Reply to
Fred Rabouw

My experience if GigE is that it's difficult to make that happen. Negotiation is mandated; if you turn it off at one end the port that is trying to negotiate won't come up; if you turn it off at both ends you can cause a duplex problem, but why would you bother?

Sam

Reply to
Sam Wilson

Good idea, but no, both sides are reporting:

Full-duplex, 1000Mb/s, media type is RJ45

Reply to
Aharon Schkolnik

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