3550 to 3550 connection on cat 5: Crossover or Straight

[hstechcorp]

Hi,

I am connecting Cat 3550 EMI (SW1) to Cat 3550 SMI (SW2).

The cable connection is as follows:

1- Sw1 to Patch Panel 1 (Straight)

2- Patch Panel 1 to Patch Panel 2 (Straight)

3- Patch Panel 2 to Sw 2 (Cross over)

The ports are configured as:

!

interface FastEthernet0/21

description JCITYSW02 trunk connection

switchport trunk encapsulation dot1q

switchport mode trunk

no ip address

end

Global commands:

spanning-tree mode pvst

spanning-tree extend system-id

Problem is switches are not able to see each other.

What am I missing?

Please help.

Thanks,

Asif.

[JamesLuther]

Hello Asif,

In theory your setup looks OK.

Have you tried putting a direct (x-over) cable between the two switches?

Have you tried using a different patch panel interlink?

What does sh int fa0/21 show? ie is it down/down?

Regards

[hstechcorp]

No, I did not try putting a direct x-over cable between two switches neither different patch panel interlink.

The output of sh int fa 0/21 shows:

FastEthernet0/21 is up, line protocol is up (connected)

Hardware is Fast Ethernet, address is 000d.28fd.4315 (bia 000d.28fd.4315)

Description: JERCITYSW02 trunk connection

MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,

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

Encapsulation ARPA, loopback not set

Keepalive set (10 sec)

Full-duplex, 100Mb/s

input flow-control is off, output flow-control is off

ARP type: ARPA, ARP Timeout 04:00:00

Last input 00:00:01, output 00:00:00, output hang never

Last clearing of "show interface" counters never

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: fifo

Output queue :0/40 (size/max)

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute ouxtput rate 0 bits/sec, 0 packets/sec

214205 packets input, 30044425 bytes, 0 no buffer

Received 48145 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

0 watchdog, 40525 multicast, 0 pause input

0 input packets with dribble condition detected

2148548 packets output, 500501024 bytes, 0 underruns

0 output errors, 0 collisions, 11 interface resets

0 babbles, 0 late collision, 0 deferred

0 lost carrier, 0 no carrier, 0 PAUSE output

0 output buffer failures, 0 output buffers swapped out

[greg.washburn]

Are you saying you do not see the partner switch layer 2 mac address when you issue "show mac address-table" or that they cannot see one another at layer 3 IP address?

[JamesLuther]

Hi,

Your ports are showing up/up. Therefore the switches are connected together OK on a physical layer.

What exactly is the problem?

What does "sh cdp nei" tell you?

Regards

[hstechcorp]

Sh Cdp nei does not show the neighboring switch. Sw1 does not Sw2 and vice versa.

[hstechcorp]

I did not check mac table, but I cant ping from one switch to other. The show cdp nei on both switch does not show any entry for other.

[greg.washburn]

I would prefer to use show mac address-table over show cdp neighbor because we do not know that cdp is running (is by default) or that it has not been disabled on a given port.

Having said that can you please show us the output from each switch given the following command:

"show run int vlan 1"

[hstechcorp]

Here is the output:

Sw1:

Building configuration...

Current configuration : 91 bytes

!

interface Vlan1

ip address 192.168.10.1 255.255.255.0

ip helper-address 10.1.10.5

end

SW2:

Current configuration : 91 bytes

!

interface Vlan1

ip address 192.168.10.12 255.255.255.0

ip helper-address 10.1.10.5

end

[Thotsaphon Lueangwattanaphong]

Asif,

SW1:

(conf)#cdp run

SW2:

(conf)#cdp run

I just want to know which one of them is responsible to be a gateway of VLAN1. Are they running as Layer3 switch?

Toshi

[hstechcorp]

CDP is running as I can see other cisco devices when I do sh cdp nei.

SW1 is the gateway of vlan1.

[Thotsaphon Lueangwattanaphong]

Asif,

First of all if the switch1 is responsible to be a gateway of vlan1. At switch2 I would take an ip-helper command off. Please post the configuration of both interfaces from both switches.

Can you use a "show cdp ne" command on both switched and see other switches but these two?

Toshi

[hstechcorp]

Yes, I can use cdp neighbor but cant see the SW1 from SW2 and vice versa. However, I can see all other cisco devices connected to SW1 or SW2.

I am not on site right now, will post interface config later.

Thanks

[Edison Ortiz]

1- Sw1 to Patch Panel 1 (Straight)

2- Patch Panel 1 to Patch Panel 2 (Straight)

3- Patch Panel 2 to Sw 2 (Cross over)

Either use 'Straight-through Cabling' to the patch panel on both switches' uplinks or use 'Crossover Cabling' on both.

I haven't seen this type of cabling implemented before and I'm not sure if it's going to work.

With today's auto-mdix implementation, I see 'Straight-through Cabling' implemented across the board.

__

Edison.

[hstechcorp]

Edison,

Thanks for your suggestion. I tried with Straight through cabling first, but connection did not come up. Then I tried with one side of crossover, which was able to bring the connection up for some time. Then it went down.

I think its more of a physical cabling issue, if my configuration is correct. Can you please check the config and let me know if I have any problems there.

Thanks,