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Glen KrinskyFlag for United States of America

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Why Can't I Ping?

Ok.  I would like to know why I can't ping some of the nodes on my network.  I use a CISCO 3750G as a CORE SWITCH with 6 seperate LANs.  4 of the six use 3750G switches and the other 2 use 2950G switches.  Now, I can ping the 2950's and 1 of the 3750's but that's it.  I have attached the configuration files of the CORE Switch, one 3750 that I can ping and one that I can't.  I have also included the router configs for each.
Avatar of rauenpc
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interface Vlan10
 description CORE_VLAN
 ip address
 no ip route-cache cef
 no ip route-cache
 no ip mroute-cache

interface Vlan10
 ip address
 no ip route-cache cef
 no ip route-cache
 no ip mroute-cache

interface FastEthernet0/0.3
 description FRC Engineering Interface
 encapsulation dot1Q 3
 ip address
 ip flow ingress
 ip flow egress
interface FastEthernet0/0.4
 encapsulation dot1Q 4
 ip flow ingress
 ip flow egress
interface FastEthernet0/0.6
 description 378 Engineering Router Interface
 encapsulation dot1Q 6
 ip address
 ip flow ingress
 ip flow egress
interface FastEthernet0/0.8
 description 270 Engineering Router Interface
  encapsulation dot1Q 8
 ip address
 ip flow ingress
 ip flow egress

interface Vlan1
 ip address
interface Vlan2
 no ip address
interface Vlan3
 no ip address
interface Vlan4
 no ip address
interface Vlan8
 no ip address
ip classless
ip route

LAB270: vlan 10,
270TEST: vlan 10, 192.168. 170.  0/24
ENGrouter: fa0/0.8, vlan 8,

There are many IP mismatches, vlan mismatches, and missing (default) routes on the switches. Go through your configs and make sure things line up correctly.
for core, ping the gateway, not the individual device
Avatar of Glen Krinsky


@rauenpc-  Remember, I have 6 seperate LAN's.  They are not mismatches there are 6 seperate IP addresses.,,,,, and
If you are trying to configure intervlan routing, each Vlan interface at the core needs an ip address.
The VLAN's need to be tagged for all of them to be able to ping each other. VLAN's only go through trunked ports.
Run the following commands
On the core switch and paste a scrambled output

Show CDP neighbors
Show ip interfaces brief
Show VTP

Let's start with theses three
I meant
Show VTP status
Is IP route enabled on the 3750
Yes, IP Route is enabled.

run the test commands above to see why the routes are not traversing.
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
                  S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone,
                  D - Remote, C - CVTA, M - Two-port Mac Relay

Device ID        Local Intrfce     Holdtme    Capability  Platform  Port ID
                 Gig 1/0/12        127             R S I  2811      Fas 0/0
                 Gig 1/0/23        146             R S I  2811      Fas 0/0
                 Gig 1/0/1         177              S I   WS-C2960G Gig 0/7
LAB_FRC_TEST     Gig 1/0/2         160              S I   WS-C2960G Gig 0/7
LAB_270_ENG      Gig 1/0/5         120              S I   WS-C3750G Gig 1/0/24
LAB_378_ENG      Gig 1/0/3         179              S I   WS-C3750G Gig 1/0/24
                 Gig 1/0/11        146             R S I  2811      Fas 0/0
Lab_378_TEST     Gig 1/0/4         179              S I   WS-C3750G Gig 1/0/24
LAB_270_TEST     Gig 1/0/6         164              S I   WS-C3750G Gig 1/0/24
LAND_SWITCH2     Gig 1/0/14        148             R S I  WS-C3750G Gig 1/0/31
LAND_SWITCH2     Gig 1/0/13        148             R S I  WS-C3750G Gig 1/0/15


VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Gi1/0/7, Gi1/0/8, Gi1/0/9
                                                Gi1/0/10, Gi1/0/17, Gi1/0/18
                                                Gi1/0/19, Gi1/0/20, Gi1/0/21
2    FRC_ENG_SEAWATCH                 active    
3    378_ENG_SEAWATCH                 active    Gi1/0/1, Gi1/0/15
4    FRC_TEST_SEAWATCH                active    Gi1/0/2, Gi1/0/16
5    378_TEST_SEAWATCH                active    Gi1/0/4
6    SEAWATCH_172.16.100.0            active    Gi1/0/3, Gi1/0/13
7    SEAWATCH_172.16.200.0            active    Gi1/0/14
8    270_ENG_SEAWATCH                 active    Gi1/0/5
9    270_TEST_SEAWATCH                active    Gi1/0/6
10   VLAN0010                         active    
11   test                             active    
12   VLAN0012                         active    
16   VLAN0016                         active    
22   VLAN0022                         active    
1002 fddi-default                     act/unsup
1003 token-ring-default               act/unsup
1004 fddinet-default                  act/unsup
VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1005 trnet-default                    act/unsup

VLAN Type  SAID       MTU   Parent RingNo BridgeNo Stp  BrdgMode Trans1 Trans2
---- ----- ---------- ----- ------ ------ -------- ---- -------- ------ ------
1    enet  100001     1500  -      -      -        -    -        0      0  
2    enet  100002     1500  -      -      -        -    -        0      0  
3    enet  100003     1500  -      -      -        -    -        0      0  
4    enet  100004     1500  -      -      -        -    -        0      0  
5    enet  100005     1500  -      -      -        -    -        0      0  
6    enet  100006     1500  -      -      -        -    -        0      0  
7    enet  100007     1500  -      -      -        -    -        0      0  
8    enet  100008     1500  -      -      -        -    -        0      0  
9    enet  100009     1500  -      -      -        -    -        0      0  
10   enet  100010     1500  -      -      -        -    -        0      0  
11   enet  100011     1500  -      -      -        -    -        0      0  
12   enet  100012     1500  -      -      -        -    -        0      0  
16   enet  100016     1500  -      -      -        -    -        0      0  
22   enet  100022     1500  -      -      -        -    -        0      0  
1002 fddi  101002     1500  -      -      -        -    -        0      0  
1003 tr    101003     1500  -      -      -        -    srb      0      0  
1004 fdnet 101004     1500  -      -      -        ieee -        0      0  
1005 trnet 101005     1500  -      -      -        ibm  -        0      0  


Primary Secondary Type              Ports
------- --------- ----------------- ------------------------------------------


Interface               VTP Status
 GigabitEthernet1/0/1     enabled
 GigabitEthernet1/0/2     enabled
 GigabitEthernet1/0/3     enabled
 GigabitEthernet1/0/4     enabled
 GigabitEthernet1/0/5     enabled
 GigabitEthernet1/0/6     enabled
 GigabitEthernet1/0/7     enabled
 GigabitEthernet1/0/8     enabled
 GigabitEthernet1/0/9     enabled
 GigabitEthernet1/0/10    enabled
 GigabitEthernet1/0/11    enabled
 GigabitEthernet1/0/12    enabled
 GigabitEthernet1/0/13    enabled
 GigabitEthernet1/0/14    enabled
 GigabitEthernet1/0/15    enabled
 GigabitEthernet1/0/16    enabled
 GigabitEthernet1/0/17    enabled
 GigabitEthernet1/0/18    enabled
 GigabitEthernet1/0/19    enabled
 GigabitEthernet1/0/20    enabled
 Interface               VTP Status
 GigabitEthernet1/0/21    enabled
 GigabitEthernet1/0/22    enabled
 GigabitEthernet1/0/23    enabled
 GigabitEthernet1/0/24    enabled

I have to go back to the lan to do the sh ip int brief.
You ran "show vtp int" instead of "show vtp status"

Also, please provide a simple diagram. I was going to create a diagram for it to see how they are connected.

I will check it out later in the evening (PT).
Ok.  I figured it out with your suggestion of IP Routing.  It was off on the LAN I could ping and on on the others.  Once I turned it off, I can ping each LAN from each other.  However, I still cannot ping ANYTHING on or from the core switch.
Any thoughts on the core switch issue?  I am assuming I need to have an IP to ping and respond to pings, but I can't assign it anything other than an IP address pool.
I will take a deep look at the configuration and get back to you. I was very busy yesterday and today despite being under the weather. Do you have a brief diagram as to how these units are connected - it will save me some time finding the bottleneck
It is attached to another question I have open...

To Trunk or Not To Trunk
Drawing1.vstUser generated imageThe diagram you pointed me to has no information that I need.

I made a simple diagram based on the information I found. See attached
I noticed that the switchports connecting to other switches on the Core switch are set to access mode (They should be trunk ports connected with a crossover cable. They shouldn't be assigned to a vlan either. You would assign vlans to access switches)

Review Cisco's 3-Layered Hierarchical Model (Access Layer, Distribution Layer and Core Layer)

You didn't give me the VTP status info to see if vlans created on the core switch (which I recommend should be the only VTP server) is replicated to the other switches.

I also noticed that there are 2 connections to Land switch 2 via port 13 and 14 - Initially I thought you created an etherchannel but saw that the ports are access ports two which makes etherchannel impossible on those links.

VTP Version Capable     :  1 to 3
VTP Version Running     :  1
VTP Domain Name         :  NEWPALM
VTP Pruning Mode         :  Disabled
VTP Traps Generation    :  Disabled
Device ID                       :  0013.193e.1880
Configuration last modified by at 3-13-93 10:27:54.
Local updater ID is (no valid interface found)

Feature VLAN
VTP Operating Mode     :Server
Maximum VLANS supported locally:     1005
Number of existing VLANs     :  18
Configuration Rvision     :  117
MD5 Digest     :  Blah blah blah...
Did you change the port settings to trunk?

Check the VTP status on the other switches to see if VLAN information is replicated to them (you don't have to post the results)
It is not replicated to all switches.  I have not set the ports to trunk yet.  I am assuming that the new port settings will look like this...?

interface GigabitEthernet0/3
 description 270_Engineering_LAN
 switchport trunk encapsulation dot1q
 switchport mode trunk

How does this affect the other end?  It currently looks like this...

interface FastEthernet0/0.8
 description 270 Engineering Router Interface
  encapsulation dot1Q 8
 ip address
 ip flow ingress
 ip flow egress
Avatar of David Akinsanya
David Akinsanya
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So on the LAN Switch

int gi1/0/24
 description bl;ah blah blah
 switchport trunk encapsulation dot1q
 switchport mode trunk

On the core
interface GigabitEthernet1/0/5
 description 270_Engineering_LAN
 switchport trunk encapsulation dot1q
 switchport mode trunk

And on the router...

interface FastEthernet0/0.8
 description 270 Engineering Router Interface
  encapsulation dot1Q 8
 ip address
 ip flow ingress
 ip flow egress

The port on the Core_Switch (G1/0/11) that connects to F0/0 on the Seawatch_Eng_Router must also be a trunk port.

interface GigabitEthernet1/0/11
 description 270_Engineering_LAN
 switchport trunk encapsulation dot1q
 switchport mode trunk
Ok.  I will give it a shot after the new year.
Ok...I failed appearently.  This is what I tried.

On the local LAN...(This is a 2960 BTW...)

int gi0/7
description FRC_ENG
Switchport trunk native vlan 3
switchport mode trunk

vlan 3
no ip address

On the Core Switch...(3750G)

int gi1/0/1
description FRC_ENG
switchport encapsulation dot1q
switchport mode trunk
(I also tried with switchport trunk native vlan 3)

vlan 3
no ip address

On the ENG Router (2811)

int fa0/0.3
encapsulation dot1q 3
ip address

This did not work.  What am I missing?
Native vlan is for untagged packets. Traffic from any device not tagged on the switchport is assigned to whatever vlan you identify as native.

You must have your native vlans the same throughout your network or you'll get native vlan mismatch messages - which results in bridged vlans.

I think I understand what you are trying to do.
Looks like you want to have a management vlan.

That is a completely different setup.
The currect setup is to segment you network into multiple vlans and control how traffic traverses within. To manage your switches you will have to put the switch in a management vlan, let's assume you chose 3 as your managment vlan.

On every switch, you would configure the following
Switch(config)# interface vlan 3
Switch(config-int)# ip address 192.168.100.x
Switch(config)# ip default-gateway
No.  In our field environment, we assign a port to native vlan 7 and set the port to trunk.

int gi0/7
switchport trunk native vlan 7
switchport mode trunk

I do not know what is on the other side of the switch in the field.  However, I do know what my lab setup is.  Their is no other changes made to the LAN switch other than setting the trunk to native valn 7.  From the LAN switch, it goes to another switch that I do not have access to, after that, I do not know where it goes.  I assume to a border router somewhere.
Read up of Native Vlan and Native Vlan Mismatch

Switch A = Native Vlan 7
Switch B = Native Vlan 3

You will see a lot of native vlan mismatches on your debug output.

The result of this is, broadcast messages sent from untagged packets from switch A (vlan 7) will appear in switch B (vlan 3) because both networks are now bridged together. That defeats the purpose of vlan in the first place because one of the main reasons you create vlans is to separate networks into multiple broadcast domains, etc.
So bottom line is I need to know how the other side of the field environment is set up to avoid the mismatch errors.
Thanks for all your help.  I did not fix the issue yet, but I am on the right path.
A strong network is built layer by layer (OSI model).
Layer 1, involves correct cabling etc
Layer 2, involves appropriate port configurations and assignment.

In your case, we're dealing with Layer 2 issues

You are definitely on the right path -

All the best