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New Member

cann't ping

Good Day

Our company has a problem. Would you be so kind to help us.

Here is a short description of our problem

Our clients have a network with the topology that described below. Two switches 2900XL are connected by FEC and it is used 2/1-2/4(100FX). switches have IP-10.1.1.2 and IP-10.1.1.3 correspondingly. To each switches (2900XL) is connected Cat2950s using by trunk connection (1/1-1/4100FX).The switches 2950 (10.1.1.4, 10.1.1.5, 10.1.1.6) are connected to the first switch with ip 10.1.1.2(2900XL) and the switches 2950(10.1.1.7,10.1.1.8,10.1.1.9) are connected to the second switch with ip 10.1.1.3(2900XL). . All switches 2950 have 2950 IOS- 12.1(19)EA1a, and all switches 2900XL have IOS-12.0(5)WC9. The switch 2900XL(10.1.1.2) are connected to the 2621 to achieve routing between VLANs.

There are four problems:

1). Ping from any 2950(10.1.1.4(5,6)) was successful and passed to the 2900XL(10.1.1.2). Ping command from 2950(10.1.1.4(5,6)) did not passed to the other 2950(10.1.1.4(5,6)) and 2900XL(10.1.1.3) which are connected to the 2900XL(10.1.1.2), till then 2900XL has not made Ping by itself to the switch. In other words switches can make Ping command through 2900XL. After 3 or 5 minutes situation comes back.

2). All uplinks 2950XL have ignored frames. Broadcasting frames about 70-80 %.

3). At one of the 2950(10.1.1.7) big,very big , large and huge buffers have failures

4). On the both 2900XL at the loading procces have appeared mistake “LINK-4-ERROR Fast1/1 is experiencing errors”.. When we unplug this interface and make a reload we have the same problem on the next interface.

There are no redundant links in configuration. Speed and duplex on the trunk connection at the both side are tunned up in a similar manner. FEC is tunned up correctly. The type of topology is a star. The protocol CDP is switched off.

Please give your advise what is the problem? If this is the mistake of the equipment then what switch is wrong?

Whait to hear from you soon.

Thank you in advance.

8 REPLIES
New Member

Re: cann't ping

Are you sure your FEC is OK?

Because of the broadcast and the buffers it seems you have a loop. Do you have SPT working in the vlan?

Can send information about SPT from the CLI of your switches?

About the FEC?

Can you see the SPT topology OK in your switches?

New Member

Re: cann't ping

10.1.1.2, 10.1.1.4, 10.1.1.11(2900XL).

10.1.1.2->router(2621).

Other switches are 2950.

Toplogy of the network is STAR(it is about STP).Can problems failures be here(STP)?

The number of users is about 80-100.

New Member

Re: cann't ping

Have somebody else any ideas regardinng this problem?

New Member

Re: cann't ping

Just curious, did this problem just start, or is this a new installation?

New Member

Re: cann't ping

The only thing that strikes me is the use of the "native" command on the router for VLAN 1.

"Configuring IEEE 802.1Q VLAN Encapsulation

On an IEEE 802.1Q trunk port, all transmitted and received frames are tagged except for those on the VLAN configured as the native VLAN for the port. Frames on the native VLAN are always transmitted untagged and are normally received untagged."

This may create problems for some of the other trunks that allow VLAN1 since these frames are tagged when they leave the router.

Although this is probalby not the problem since all the switches have a VLAN1 in the same network, and same vlan, there should be no routing involved at all.

Maybe you could post the output of the sh spanning for VLAN 1?

New Member

Re: cann't ping

spanning tree is turn off.

New Member

Re: cann't ping

...............

................

!

interface FastEthernet0/0

no ip address

duplex auto

speed auto

!

interface FastEthernet0/0.1

encapsulation dot1Q 1 native

ip address 10.1.1.1 255.255.255.0

!

interface FastEthernet0/0.4

description PLAN

encapsulation dot1Q 4

ip address 10.1.4.1 255.255.255.0

!

interface FastEthernet0/0.11

encapsulation dot1Q 11

ip address 10.1.11.101 255.255.255.0

!

interface FastEthernet0/0.15

encapsulation dot1Q 15

ip address 10.1.15.1 255.255.255.0

.............

.............

New Member

Re: cann't ping

sorry,topology ---

....2950(10.1.1.5)...2950(10.1.1.8)

...................\...............|

....................\..............|

10.1.1.1-----2900XL(10.1.1.2)----2900XL(10.1.1.11)

.......................||||

................2900xl(10.1.1.4)-10.1.1.6

................../........|.......\

.10.1.1.3....10.1.1.7...10.1.1.9

.............................||

..........................10.1.1.10

10.1.1.1-router

10.1.1.2(4,11)-2900XL.

Other -2950

2). All uplinks 2950 have ignored frames and broadcasting frames about 70-80 %. 10.1.1.11-has not ignoreds

3). At one of the 2950(10.1.1.3) big,very big , large and huge buffers have failures

4). On the both 2900XL at the loading procces have appeared mistake “LINK-4-ERROR Fast1/1 is experiencing errors”.. When we unplug this interface and make a reload we have the same problem on the next interface.

STP is turn off.

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