Networking.Reborn
Friday 29 November 2013
Monday 20 May 2013
How to enable telnet on Cisco Catalyst Switches?
Dear friends, we will discuss on how to enable telnet to Cisco Catalyst Switches and all other applicable devices.
Switch#conf t Switch(config)#line vty 0 15 Switch(config-line)#password cisco Switch(config-line)#login Switch(config-line)#end |
Switch#conf t Switch(config)#enable password cisco Switch(config)#end |
I hope this post will benefit you guys. Thank you for dropping by.
- Soulpower
How to configure a VLAN Trunking Protocol (VTP) ?
Hi. Let's discuss on how to setup a basic VTP configuration.
Network setup
Network setup
2 units of Cisco Catalyst 2950 are connected to each other via trunk port. SwitchA will be chosen as the VTP Server, SwitchB will be the VTP client.
Steps
1. This step is not compulsory. But to make it easier, I have reset my VLAN and VTP database to default settings. You can learn how to do it here.
2. Configure at least one trunk port on both switches, because VTP packets will use trunk port to communicate. In this case, I'm using port Fa0/8 on both switches as trunk port. ISL is not available on this switch, therefore, dot1q is used by default.
3. Verify your configuration. Make sure it's being set as trunk port. Catalyst 2950 is using dot1q as default trunking encapsulation, therefore, I don't need to configure it manually.
4. Now, let's configure VTP. Please make sure that the VTP domain name and VTP password is identical on both switches.
5. Now we have configured VTP on both switches. Let's confirm that by turning on VTP debug events. I noticed that, as soon as a VLAN is added, VTP Server will send a summary packet to its VTP client, less than a second.
a) A VTP summary packet is being transmitted by SwitchA (VTP Server) via its trunk port Fa0/8 to all switches within its domain (cisco).
b) A VTP summary packet is being received by SwitchB via its trunk port Fa0/8 from SwitchA.
6. VTP Revision number is now increased by 1 value (from 0 to 1), and we can see VLAN 100 is also added on SwitchB which was being added on SwitchA.
Conclusion
I hope this post will benefit you guys. Thank you for dropping by.
- Soulpower
Steps
1. This step is not compulsory. But to make it easier, I have reset my VLAN and VTP database to default settings. You can learn how to do it here.
SwitchA#sh vtp status
VTP Version : 2
Configuration Revision : 0 Maximum VLANs supported locally : 128 Number of existing VLANs : 5 VTP Operating Mode : Server VTP Domain Name : VTP Pruning Mode : Disabled VTP V2 Mode : Disabled VTP Traps Generation : Disabled MD5 digest : 0x57 0xCD 0x40 0x65 0x63 0x59 0x47 0xBD Configuration last modified by 0.0.0.0 at 0-0-00 00:00:00 Local updater ID is 10.0.0.110 on interface Vl1 (lowest numbered VLAN interface found) |
SwitchB#sh vtp status VTP Version : 2 Configuration Revision : 0 Maximum VLANs supported locally : 128 Number of existing VLANs : 5 VTP Operating Mode : Server VTP Domain Name : VTP Pruning Mode : Disabled VTP V2 Mode : Disabled VTP Traps Generation : Disabled MD5 digest : 0x57 0xCD 0x40 0x65 0x63 0x59 0x47 0xBD Configuration last modified by 0.0.0.0 at 0-0-00 00:00:00 Local updater ID is 10.0.0.111 on interface Vl1 (lowest numbered VLAN interface found) |
SwitchA(config)#int fa0/8 SwitchA(config-if)#switchport mode trunk SwitchA(config-if)#end |
SwitchB(config)#int fa0/8 SwitchB(config-if)#switchport mode trunk SwitchB(config-if)#end |
SwitchA#sh int f0/8 switchport Name: Fa0/8 Switchport: Enabled Administrative Mode: trunk Operational Mode: up Administrative Trunking Encapsulation: dot1q Negotiation of Trunking: On Access Mode VLAN: 1 (default) Trunking Native Mode VLAN: 1 (default) Voice VLAN: none Administrative private-vlan host-association: none Administrative private-vlan mapping: none Administrative private-vlan trunk native VLAN: none Administrative private-vlan trunk encapsulation: dot1q Administrative private-vlan trunk normal VLANs: none Administrative private-vlan trunk private VLANs: none Operational private-vlan: none Trunking VLANs Enabled: ALL Pruning VLANs Enabled: 2-1001 Capture Mode Disabled Capture VLANs Allowed: ALL Protected: false Appliance trust: none |
SwitchB#sh int f0/8 switchport Name: Fa0/8 Switchport: Enabled Administrative Mode: trunk Operational Mode: up Administrative Trunking Encapsulation: dot1q Negotiation of Trunking: On Access Mode VLAN: 1 (default) Trunking Native Mode VLAN: 1 (default) Voice VLAN: none Administrative private-vlan host-association: none Administrative private-vlan mapping: none Administrative private-vlan trunk native VLAN: none Administrative private-vlan trunk encapsulation: dot1q Administrative private-vlan trunk normal VLANs: none Administrative private-vlan trunk private VLANs: none Operational private-vlan: none Trunking VLANs Enabled: ALL Pruning VLANs Enabled: 2-1001 Capture Mode Disabled Capture VLANs Allowed: ALL Protected: false Appliance trust: none |
SwitchA(config)#vtp mode server Device mode already VTP SERVER. SwitchA(config)#vtp domain cisco Changing VTP domain name from NULL to cisco SwitchA(config)#vtp password cisco Setting device VLAN database password to cisco SwitchA(config)#end |
SwitchB(config)#vtp mode client Setting device to VTP CLIENT mode. SwitchB(config)#vtp domain cisco Changing VTP domain name from NULL to cisco SwitchB(config)#vtp password cisco Setting device VLAN database password to cisco SwitchB(config)#end |
a) A VTP summary packet is being transmitted by SwitchA (VTP Server) via its trunk port Fa0/8 to all switches within its domain (cisco).
b) A VTP summary packet is being received by SwitchB via its trunk port Fa0/8 from SwitchA.
SwitchA#debug sw-vlan vtp events vtp events debugging is on SwitchA# SwitchA(config)#vlan 100 SwitchA(config-vlan)#name ciscovlan SwitchA(config-vlan)#end SwitchA# 00:28:56: VTP LOG RUNTIME: Transmit vtp summary, domain cisco, rev 1, followers 1, tlv blk size 5 (inc #tlv field), MD5 digest calculated = 8D 6C F5 D2 A8 3D B0 F5 29 38 B0 A0 A7 01 6F EB 00:28:56: VTP LOG RUNTIME: Summary packet received, domain = cisco, rev = 1, followers = 1, length 77, trunk Fa0/8 00:28:56: VTP LOG RUNTIME: Summary packet rev 1 equal to domain cisco rev 1 00:28:56: VTP LOG RUNTIME: Subset packet received, domain = cisco, rev = 1, seq = 1, length = 228 |
SwitchB#debug sw-vlan vtp events vtp events debugging is on SwitchB# 00:50:42: VTP LOG RUNTIME: Summary packet received, domain = cisco, rev = 1, followers = 1, length 77, trunk Fa0/8 00:50:42: VTP LOG RUNTIME: Summary packet rev 1 greater than domain cisco rev 0 00:50:42: VTP LOG RUNTIME: Domain cisco currently not in updating state 00:50:42: VTP LOG RUNTIME: pdu len 77, #tlvs 1 00:50:42: VTP LOG RUNTIME: Subset packet received, domain = cisco, rev = 1, seq = 1, length = 228 00:50:42: VTP LOG RUNTIME: Transmit vtp summary, domain cisco, rev 1, followers 1, tlv blk size 5 (inc #tlv field), MD5 digest calculated = 8D 6C F5 D2 A8 3D B0 F5 29 38 B0 A0 A7 01 6F EB |
SwitchA#sh vtp status VTP Version : 2 Configuration Revision : 1 Maximum VLANs supported locally : 128 Number of existing VLANs : 6 VTP Operating Mode : Server VTP Domain Name : cisco VTP Pruning Mode : Disabled VTP V2 Mode : Disabled VTP Traps Generation : Disabled MD5 digest : 0x8D 0x6C 0xF5 0xD2 0xA8 0x3D 0xB0 0xF5 Configuration last modified by 10.0.0.110 at 3-1-93 00:28:56 Local updater ID is 10.0.0.110 on interface Vl1 (lowest numbered VLAN interface found) SwitchA#sh vlan VLAN Name Status Ports ---- -------------------------------- --------- ------------------------------- 1 default active Fa0/1, Fa0/5, Fa0/6, Fa0/7, Fa0/9, Fa0/10, Fa0/11, Fa0/12 100 ciscovlan active 1002 fddi-default act/unsup 1003 token-ring-default act/unsup 1004 fddinet-default act/unsup 1005 trnet-default act/unsup VLAN Type SAID MTU Parent RingNo BridgeNo Stp BrdgMode Trans1 Trans2 ---- ----- ---------- ----- ------ ------ -------- ---- -------- ------ ------ 1 enet 100001 1500 - - - - - 0 0 100 enet 100100 1500 - - - - - 0 0 1002 fddi 101002 1500 - - - - - 0 0 1003 tr 101003 1500 - - - - - 0 0 1004 fdnet 101004 1500 - - - ieee - 0 0 1005 trnet 101005 1500 - - - ibm - 0 0 Remote SPAN VLANs ------------------------------------------------------------------------------ Primary Secondary Type Ports ------- --------- ----------------- ------------------------------------------ |
SwitchB#sh vtp status VTP Version : 2 Configuration Revision : 1 Maximum VLANs supported locally : 128 Number of existing VLANs : 6 VTP Operating Mode : Client VTP Domain Name : cisco VTP Pruning Mode : Disabled VTP V2 Mode : Disabled VTP Traps Generation : Disabled MD5 digest : 0x8D 0x6C 0xF5 0xD2 0xA8 0x3D 0xB0 0xF5 SwitchB#sh vlan VLAN Name Status Ports ---- -------------------------------- --------- ------------------------------- 1 default active Fa0/1, Fa0/2, Fa0/3, Fa0/4, Fa0/5, Fa0/6, Fa0/7, Fa0/9, Fa0/10, Fa0/11, Fa0/12 100 ciscovlan active 1002 fddi-default act/unsup 1003 token-ring-default act/unsup 1004 fddinet-default act/unsup 1005 trnet-default act/unsup VLAN Type SAID MTU Parent RingNo BridgeNo Stp BrdgMode Trans1 Trans2 ---- ----- ---------- ----- ------ ------ -------- ---- -------- ------ ------ 1 enet 100001 1500 - - - - - 0 0 100 enet 100100 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 Remote SPAN VLANs ------------------------------------------------------------------------------ Primary Secondary Type Ports ------- --------- ----------------- ------------------------------------------ |
- We can see that our VTP has been configured correctly, and we have verified that it's working fine as it should.
- Please be advised that VTP is a layer 2 Cisco Proprietary Protocol, please do not attempt to implement this on other switches. :)
I hope this post will benefit you guys. Thank you for dropping by.
- Soulpower
How to reset passwords on a Cisco Catalyst Switch ?
Hi, today we'll discuss on how to reset all passwords on a Cisco Catalyst switches.
Steps
1. Make sure you are connected to the switch via console connection.
2. Power down the switch.
3. While the switch is turned off, press and hold "Mode" button that is located in front, on the left side of the switch. Please refer below image.
4. Next, power on the switch. Remember, you still need to hold the "Mode" button.
5. Release the "Mode" button after approximately 5 seconds when the Status (STAT) LED goes out. When you release the Mode button, the SYST LED blinks amber.
6. The console message will be displayed like this:
7. Enter command "flash_init".
8. Then, enter command "load_helper", nothing will happen next.
9. Enter "dir flash:" command. The switch file system will be displayed as below.
10. Type in rename flash:config.text flash:config.old. config.text is where the password (that you have forgotten) is stored.
12. When you see "Press RETURN to get started!" , type rename flash:config.old flash:config.text to rename the configuration file to its original file.
14. Finally, please configure a new password to your Switch, and please remember it. Otherwise, you'll need to repeat these steps again. :D
15. Write the running configuration to the configuration file with the write memory command.
I hope this post will benefit you guys. Thank you for dropping by.
- Soulpower
1. Make sure you are connected to the switch via console connection.
2. Power down the switch.
3. While the switch is turned off, press and hold "Mode" button that is located in front, on the left side of the switch. Please refer below image.
4. Next, power on the switch. Remember, you still need to hold the "Mode" button.
5. Release the "Mode" button after approximately 5 seconds when the Status (STAT) LED goes out. When you release the Mode button, the SYST LED blinks amber.
6. The console message will be displayed like this:
C2950 Boot Loader (C2950-HBOOT-M) Version 12.1(11r)EA1, RELEASE SOFTWARE (fc1) Compiled Mon 22-Jul-02 17:18 by antonino WS-C2950-12 starting... Base ethernet MAC Address: 00:0d:bc:01:a0:40 Xmodem file system is available. The system has been interrupted prior to initializing the flash filesystem. The following commands will initialize the flash filesystem, and finish loading the operating system software: flash_init load_helper boot switch: |
switch: flash_init Initializing Flash... flashfs[0]: 7 files, 1 directories flashfs[0]: 0 orphaned files, 0 orphaned directories flashfs[0]: Total bytes: 7741440 flashfs[0]: Bytes used: 3139072 flashfs[0]: Bytes available: 4602368 flashfs[0]: flashfs fsck took 5 seconds. ...done initializing flash. Boot Sector Filesystem (bs:) installed, fsid: 3 Parameter Block Filesystem (pb:) installed, fsid: 4 switch: |
switch: load_helper |
switch: dir flash: Directory of flash:/ 2 -rwx 660 <date> vlan.dat 7 -rwx 2412 <date> config.text 3 -rwx 3132319 <date> c2950-i6q4l2-mz.121-22.EA14.bin 5 -rwx 316 <date> env_vars 6 -rwx 5 <date> private-config.text 21 -rwx 109 <date> info 22 -rwx 109 <date> info.ver 4602368 bytes available (3139072 bytes used) switch: |
switch: rename flash:config.text flash:config.old |
11. Enter "boot" command. This command will reboot the switch (obviously).
switch: boot Loading "flash:/c2950-i6q4l2-mz.121-22.EA14.bin"...############################################################## |
12. When you see "Press RETURN to get started!" , type rename flash:config.old flash:config.text to rename the configuration file to its original file.
SwitchB#rename flash:config.old flash:config.text Destination filename [config.text] |
13. Then, type copy flash:config.text system:running-config to copy the configuration file into the memory.
SwitchB#copy flash:config.text system:running-config Destination filename [running-config]? 840 bytes copied in 0.772 secs (1088 bytes/sec) SwitchB# |
SwitchB(config)#enable secret xxx SwitchB(config)#enable password xxx SwitchB(config)#line vty 0 15 SwitchB(config-line)#password xxx SwitchB(config-line)#login SwitchB(config)#line con 0 SwitchB(config-line)#password xxx |
SwitchB# write memory |
- Soulpower
How to reset VLAN and VTP to factory default settings ?
Hi guys, let's discuss on how to reset VLAN and VTP database to factory default settings. This example is made by using Cisco Catalyst 2950.
Steps
1. VLAN and VTP information are stored in vlan.dat file which is located in flash.
2. To display files in flash, enter the command dir flash: or show flash. You will see the file vlan.dat.
4. Delete the file by following below command.
5. Reload the switch by entering below command.
6. After reload, the VLAN and VTP data will be set to default settings.
I hope this post will benefit you guys. Thank you for dropping by.
- Soulpower
Steps
1. VLAN and VTP information are stored in vlan.dat file which is located in flash.
2. To display files in flash, enter the command dir flash: or show flash. You will see the file vlan.dat.
SwitchB#dir flash: Directory of flash:/ 2 -rwx 660 Mar 01 1993 02:13:00 +00:00 vlan.dat 7 -rwx 2412 Mar 01 1993 05:11:18 +00:00 config.old 3 -rwx 3132319 Mar 01 1993 00:09:35 +00:00 c2950-i6q4l2-mz.121-22.EA14.bin 4 -rwx 840 Mar 01 1993 02:40:48 +00:00 config.text 5 -rwx 316 Mar 01 1993 00:12:13 +00:00 env_vars 21 -rwx 109 Mar 01 1993 00:05:00 +00:00 info 22 -rwx 109 Mar 01 1993 00:07:55 +00:00 info.ver 8 -rwx 5 Mar 01 1993 02:40:48 +00:00 private-config.text 7741440 bytes total (4600832 bytes free) SwitchB#show flash Directory of flash:/ 2 -rwx 660 Mar 01 1993 02:13:00 +00:00 vlan.dat 7 -rwx 2412 Mar 01 1993 05:11:18 +00:00 config.old 3 -rwx 3132319 Mar 01 1993 00:09:35 +00:00 c2950-i6q4l2-mz.121-22.EA14.bin 4 -rwx 840 Mar 01 1993 02:40:48 +00:00 config.text 5 -rwx 316 Mar 01 1993 00:12:13 +00:00 env_vars 21 -rwx 109 Mar 01 1993 00:05:00 +00:00 info 22 -rwx 109 Mar 01 1993 00:07:55 +00:00 info.ver 8 -rwx 5 Mar 01 1993 02:40:48 +00:00 private-config.text 7741440 bytes total (4600832 bytes free) |
SwitchB#delete flash:/vlan.dat Delete filename [vlan.dat]? Delete flash:/vlan.dat? [confirm] |
5. Reload the switch by entering below command.
SwitchB#reload Proceed with reload? [confirm] |
SwitchB#sh vlan VLAN Name Status Ports ---- -------------------------------- --------- ------------------------------- 1 default active Fa0/1, Fa0/2, Fa0/3, Fa0/4 Fa0/5, Fa0/6, Fa0/7, Fa0/9 Fa0/10, Fa0/11, Fa0/12 1002 fddi-default act/unsup 1003 token-ring-default act/unsup 1004 fddinet-default act/unsup 1005 trnet-default act/unsup VLAN Type SAID MTU Parent RingNo BridgeNo Stp BrdgMode Trans1 Trans2 ---- ----- ---------- ----- ------ ------ -------- ---- -------- ------ ------ 1 enet 100001 1500 - - - - - 0 0 1002 fddi 101002 1500 - - - - - 0 0 1003 tr 101003 1500 - - - - - 0 0 1004 fdnet 101004 1500 - - - ieee - 0 0 1005 trnet 101005 1500 - - - ibm - 0 0 Remote SPAN VLANs ------------------------------------------------------------------------------ Primary Secondary Type Ports ------- --------- ----------------- ------------------------------------------ SwitchB#sh vtp status VTP Version : 2 Configuration Revision : 0 Maximum VLANs supported locally : 128 Number of existing VLANs : 5 VTP Operating Mode : Server VTP Domain Name : VTP Pruning Mode : Disabled VTP V2 Mode : Disabled VTP Traps Generation : Disabled MD5 digest : 0x3F 0x17 0xC8 0xB8 0x5A 0xE3 0x01 0x66 Configuration last modified by 0.0.0.0 at 0-0-00 00:00:00 |
- Soulpower
Saturday 18 May 2013
How to configure Switched Port Analyzer (SPAN) ?
Dear friends. Today, let's discuss on how to configure a SPAN port on a Cisco Switch.
Network Setup
MacBook 10.0.0.152/24 -->f0/9 L2 switch --> f0/1 L2 switch --> Unifi Router 10.0.0.99/24 --> Internet
Dell 10.0.0.151/24 --> f0/5 L2 switch --> f0/1 L2 switch --> Unifi Router 10.0.0.99/24 --> Internet
Plan
Macbook will generate traffic to the internet. Dell laptop will capture all it's live traffic using WireShark.
Terms
Source interface: The interface where the traffic will be captured.
Destination interface: The interface where all the captured traffic will be mirrored to.
Steps
1. At the L2 switch, configure the span source interface. In this case, I want to capture all of the traffic generated from MacBook to Internet. Therefore, port f0/1 will be used as span source interface because all traffic will go through this port to go to the internet.
Switch(config)#monitor session 1 source interface fastEthernet 0/1 |
2. Configure the destination interface. All traffic that is being captured at span source interface will be mirrored to this port.
Switch(config)#monitor session 1 destination interface fastEthernet 0/5 |
3. Please take note that the destination span port's protocol status will be changed to down once you've configured it as destination interface.
Switch#sh int f0/5 status
Port Name Status Vlan Duplex Speed Type Fa0/5 monitoring 1 a-full a-100 10/100BaseTX
Switch#sh int f0/5
FastEthernet0/5 is up, line protocol is down (monitoring) |
4. To check on current SPAN port setup on that switch.
Switch#show monitor session 1
Session 1--------- Type : Local Session Source Ports : Both : Fa0/1 Destination Ports : Fa0/5 Encapsulation : Native Ingress: Disabled |
5. Live traffic that is being captured at port f0/1 of the L2 switch can be seen as per below. You're only seeing ICMP traffic because I'm generating continuous ping to 4.2.2.2 from the MacBook (10.0.0.152).
I hope that this post will benefit us all. Thank you for your time.
- Soulpower
Wednesday 27 March 2013
2. VLANs and VLAN Trunking
VLAN
In general, there are 2 types of VLANs. L2 VLAN and L3 VLAN. L means Layer in case you don't know. :P I know you must be wondering what's the differences of both VLANs, yes? Let's start with this. L2 VLAN does not have any IP address, but L3 VLAN owns an IP address and is represented as a subnet. Yes you are right. When it is Layer 3, then of course it can be routed in an IP network using routing protocols, as well as communicating with other VLANs. Please take note that unlike L3 VLAN, L2 VLAN devices cannot talk to each other unless there's a layer 3 device such as router configured as their default gateway.
Private VLANs
Will be updated soon.
VLAN Trunking Protocol (VTP)
Why do we need VTP and what is the benefit of using VTP to our network? Imagine if we have 100 switches and all of the switches needs to have the same VLAN configuration. Isn't that a lot of work for us to configure each 100 switches again and again with the same VLAN configuration? That's when VTP come to save us. If we use VTP, it advertises VLAN configuration information to the neighbouring switches so that VLAN configuration information needs to be made to only one switch, with all other switches in the network learning the VLAN information dynamically. So, we don't need to configure all 100 switches with the same VLAN configurations. Thanks to VTP!
VTP Modes
- Server Mode - Originates VTP adv., processes and update its VLAN configs, Forward received VTP adv., Saves VLAN in NVRAM or VLAN.dat, can create, modify or delete VLANs.
- Client Mode - Same as Server Mode but cannot create, modify or delete VLANs.
- Transparent Mode - Same as Server Mode but cannot originate VTP adv., and do not process adv. to update its VLAN configs.
To be continued.
-Soulpower
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