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

Upgrading a stand-alone switch:
For example: boot flash:cat3k_caa-universalk9.SSA.03.08.83.EMD.150-8.83.EMD.bin

Hence, the boot variable should not be pointing to the .bin file. If so, the switch will boot in Bundle mode. The boot variable should be pointing to the “packages.conf” file in order for the switch to boot in Install mode.

Before doing the upgrade, we need to check the mode in which the switch is currently booted in.
show version | begin Switch Port

Switch Ports Model SW Version SW Image Mode
—— —– —– ———- ———- —-
* 1 32 WS-C3850-24T 03.03.01SE cat3k_caa-universalk9 INSTALL •ß Install mode

Cisco 3850 covert from bundle to install mode:
Current mode: BUNDLE MODE

1. dir flash: – Current running IOS version should be visible.
2. Expand the file to the flash file system.
#software expand running to flash:
it take running .bin file and expand the content to the flash file system so we
can then convert from bundle to install mode.

3. Verify once expanded, All pkg file should be expanded including the very important packages.conf file.
#dir flash:

4. Change the boot variable to point to the packages.conf file.
#boot system switch all flash:packages.conf
This will cover single to multiple switches in a stack.

5. Verify the boot
#show boot
verify the boot variable and build

6. wr mem
7. reload
8. show version | begin Switch Port
9. clean the bin file
#software clean
#wr mem

Replace a Failed Cisco 3850 Switch in a Stack
1. Connect to the new switch
2. Verify the license level and IOS version.
a. In order to avoid the license mismatch.
#license right-to-use activate ipbase all acceptEULA
3. Restart

On your stack, you need to make sure the new switch come up with the same software version.
Master(global)# software auto-upgrade auto
So when we connect the new switch it will auto upgrade the same version as
the stack.

Connect the stacking cable and the power of the new switch.

Cisco Catalyst 3850 IOS Upgrade on All Stack Members – Version Mismatch

1. Connect the switches to the stack
2. Verify the license level
3. On master
#request platform software package install auto-upgrade
Auto upgrade has been initiated for the following incompatible switch
4. Reload the new member

Cisco 3850 IOS switch stack 3.x.x to 16.x.x upgrade install mode
1. We need to make sure the we do have space available on the flash:
#software clean
2. Copy the bin file active switch flash
3. Once the file is copied over we are going to regenerate rsa cryto key use for SSH and the 16.x.x release notes if your upgrading from 3.x.x to 16.x.x to generate a new crypto key.
#crypto key generate key 1024
4. Begin the software upgrade
#software install file flash:filename switch verbose new force

New – we need to create a new packages.conf to be used by the boot up process.
force – this will force actual process, 1 major code to another.. otherwise package compatibility will fail.


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