Category Archives: Switch

Cisco Switching

3850 switch – IOS XE upgrade Detailed

By default, the switches are shipped in Install mode.

Bundle mode: Bundle mode is where we boot the switch/stack using the .bin file. This is the traditional method of booting the switch where the switch extracts the .bin file to the RAM of the switch and run from there.

Install Mode: Install mode is where we pre-extract the .bin file in the flash and boot the witch/stack using the packages.conf file created during the extraction.

Install mode is the recommended mode of running the switch. Not all features may be available in this Bundle mode
Continue reading

Ether-channel on ESXI

EtherChannel: This is a link aggregation (port trunking) method used to provide fault-tolerance and high-speed links between switches, routers, and servers by grouping two to eight physical Ethernet links to create a logical Ethernet link with additional failover links. For additional information on Cisco EtherChannel, see the EtherChannel Introduction by Cisco.
LACP or IEEE 802.3ad: The Link Aggregation Control Protocol (LACP) is included in IEEE specification as a method to control the bundling of several physical ports together to form a single logical channel. LACP allows a network device to negotiate an automatic bundling of links by sending LACP packets to the peer (directly connected device that also implements LACP). For more information on LACP, see the Link Aggregation Control Protocol whitepaper by Cisco.

Note: LACP is only supported in vSphere 5.1, 5.5 and 6.0 using vSphere Distributed Switches (VDS) or the Cisco Nexus 1000v.

EtherChannel vs. 802.3ad: EtherChannel and IEEE 802.3ad standards are very similar and accomplish the same goal. There are a few differences between the two, other than EtherChannel is Cisco proprietary and 802.3ad is an open standard.
For more information on EtherChannel implementation, see the Understanding EtherChannel Load Balancing and Redundancy on Catalyst Switches article from Cisco.

Spanning Tree Feature for Optimization

Spanning Tree Feature for Optimization

Left to default settings, IEEE 802.1d STP works, but convergence might take up to a minute or more for the entire network. For instance, when the root fails, a switch must wait on the 20 second Maxage timer to expire. Then, newly forwarding ports spend 15 seconds each in listening and learning states, which makes convergence, take 50 seconds for that one switch. Over the years, Cisco added features to its STP code, and later the IEEE made improvements as well. This section covers the key optimizations to STP.




Convergence Time:


Stacking Overview

In Cisco Stack we can have all this switches virtually appear as a single chassis.
Manage all this entire stack of switches with the single mgmt. IP address.


Different Cisco Catalyst Stacking:

Switch Stack Overview:
– A switch stack is a set of up to eight stacking-capable switches connected through their stack ports.
– Stack master controls the operation of the switch stack, and is the single point of stack-wide management.
= From the stack master, you configure:
– System-level (global) features that apply to all stack members
– Interface-level features for each stack member
– Stack master contains the saved and running configuration files for the switch stack.

Prerequisites for Switch Stacks:
All stack members must run the same Cisco IOS software image to ensure compatibility among stack members.

Restrictions for Switch Stacks:
All switches in the stack must be running the LAN Base image.
In a mixed stack, the number of supported stack members is reduced from eight to four.
In a mixed stack, full stack bandwidth is reduced from 80 Gbps to 40 Gbps.
In a mixed stack, stack convergence time is increased from milliseconds to 1 to 2 seconds.

Platform and Configuration:
More Details:

Automatic Election:

TEST-SW04#sh switch
Switch/Stack Mac Address : 6416.8d2d.6680
H/W Current
Switch# Role Mac Address Priority Version State
1 Member 6416.8dd0.b880 1 0 Ready
*2 Master 6416.8d2d.6680 1 0 Ready

TEST-SW04#conf t
TEST-SW04(config)#switch 1 priority 3
Changing the Switch Priority of Switch Number 1 to 3
Do you want to continue?[confirm]
New Priority has been set successfully

Reload Switch 2:
TEST-SW04# reload slot 2(Switch03)

TEST-SW04#sh switch
Switch/Stack Mac Address : 6416.8dd0.b880
H/W Current
Switch# Role Mac Address Priority Version State
*1 Master 6416.8dd0.b880 3 0 Ready
2 Member 0000.0000.0000 0 0 Removed

TEST-SW04#sh switch stack-ports
Switch # Port 1 Port 2
——– —— ——
1 Ok Ok
2 Ok Ok

Upgrading Cisco IOS Image

Verify the Cisco upgrade path.

Download the latest IOS image for your cisco website
Go to -> IOS Software -> Select your Siwtch (for example: Cisco Catalyst Switch 3750G-24T) -> Click on “Download IP BASE” -> Select the latest version that you want to download (for example: 12-2.55.SE1).

While you are on this download page, copy/paste the MD5 given to your system. After we download the IOS image and move it to the switch, we’ll verify the MD5 checksum before installing the image.

Copy the image file from your laptop to the switch using TFTP Server.
# copy tftp flash:

Step 4
Verify and load the boot.

#show boot

#conf t
#boot system switch all flash:c3750-ipbasek9-mz-122-55.SE1.bin

Save and reboot

#wr mem

Resetting Switch

Switch#delete flash:vlan.dat – Removes the VLAN database from flash memory.
Delete filename [vlan.dat]? – Press Enter
Delete flash:vlan.dat? [confirm] – Reconfirm by pressing Enter

Switch#erase startup-config
Erasing the nvram filesystem will remove all configuration files! Continue? [confirm] – Press Enter
Erase of nvram: complete

Proceed with reload? [confirm]