Cisco Ethernet Switch Procedures
Last edited by Pete Siemsen - September 19, 2011- V5.6
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General Switch Information
Non-Privileged Commands/Procedures
Typical Port Configurations *NEW
Privileged Commands/Procedures
Hardware and Software Installation Procedures
Related documentation and other procedure pages
Cisco Switch Documentation
Cisco 6000 Series Ethernet Switch Documentation Web Location
http://www.cisco.com/univercd/cc/td/doc/product/LAN/cat6000/index.htm
Switch Login
- Login to the switch (telnet Switch Name or IP Address)
- Enter your login name
- Enter your one-time password from your CryptoCcard
- If the login was successful, a switch prompt will be returned
- If you have "Enable" level privileges, a switch prompt will be
returned (a prompt that will be like "switch-name> (enable)" to
indicate you are in "enable mode")
Switch Port Comments
Cisco Ethernet switch allow users to put a "Name" on each port. This
is a comment field that can be used as desired, and has no effect on
the operation of the switch. NCAR uses the field to show what a switch
port is connected to. In machine rooms, we put machine names in the
"Name" field. Everywhere else, we uses a standard NETS location label,
usually to specify the Wall plate interface that a port connects to. In
the automatically generated Ethernet
Switch Port Lists, the "Name" field is called the
"Connected To" field. It is also sometimes referred to as the
"comment" field in Ethernet switches.
If a switch port has been allocated permanently to a certain VLAN,
the Name field will have a P) prefix, indicating that
the port is not to be disabled, regardless of how often it is used.
These are the steps for adding and
removing a switch
Log into to ExtraView
- From your home page, select Add
- Select the NETS Add Remove Tab (at the top)
- Fill out the form and click submit
Information about the form:
- Email will be sent to all staff involved in adding or removing a
switch once the ticket is opened.
- Staff should update the ticket as work is completed (click on
complete button and click update).
- Staff assigned to the ticket will receive email every time the
ticket has been updated until their task(s) are complete.
- Marla will receive a report of all open tickets once a week.
- The ticket can be closed by the staff member assigned to the
ticket, or it will close automatically and email sent to everyone
listed on the ticket once all steps are complete.
Switch port auto-negotiation information
Web page resources to consult:
Troubleshooting
Cisco Catalyst Switches to Network Interface Card (NIC) Compatibility
Issues (Cisco)
Using
Portfast and Other Commands to Fix Workstation Startup Connectivity
Delays (Cisco)
Ethernet
Technologies (Cisco)
Configuring
and Troubleshooting Ethernet 10/100Mb Half/Full Duplex Auto-Negotiation
(Cisco)
Recovering
From errDisable Port State on the CatOS Platforms
Charles
Spurgeon's Ethernet Web Site (contains good information about
auto-negotiation)
In general, if a port cannot auto-negotiate the port speed/duplex:
- Make sure auto-negotiation is configured on both ends of the
link (use the show port command)
-- you cannot configure settings manually on one end of the link and
configure the other end of the link for auto-negotiation.
- If auto-negotiation fails when you connect a client NIC to the
switch, check the NIC and drivers to make sure that auto-negotiation is
supported.
- If auto-negotiation is supported and properly configured but you
still cannot connect, turn off auto-negotiation and set the speed and
duplex manually
(use the set port speed and set port duplex commands).
Show the Current Port Status on a
Switch
Login to the Switch (telnet Switch Name)
The following list displays various show port options
- Show the Status of all ports on the Switch
CatOS: show port
IOS: show interface status
- Show the Status of all Ports on a Card on the Switch
CatOS: show port x (where x is the
card number)
IOS: show interface status module x (where x
is the card number)
- Show the Status of one port on the Switch
CatOS: show port x/y (where x is the
card number and y is the port number)
IOS: show interface status "gig or faste"x/y
(where x is the card number and y is the port
number)
Show the Error and Data Counters for a
Port
- Login to the Switch (telnet Switch Name)
- Show the Status of one port on the Switch
CatOS: show port x/y (where x is the
card number and y is the port number)
IOS: show interface status "gig or faste"x/y
(where x is the card number and y is the port
number)
- Show the MAC level information
CatOS: show mac x/y (where x is the
card number and y is the port number)
IOS: show counters int "gig or faste"x/y (where
x is the card number and y is the port number)
- To aid in tracking down what port might be causing widespread
network problems (e.g., a gigabit ethernet host with a bad NIC causing
major network problems by spewing out large amounts of multicast
traffic):
- start by getting console access on one of the core switches
(mlra or flra) in enable mode:
- issue the 'clear counters' command to set values to zero
- then issue the 'show mac' command to see all the unicast,
multicast, and broadcast packets for all ports on the switch; if a port
is 'misbehaving' badly, the large numbers of packets should stand out
in one of the columns that command outputs and give you an indication
of which port(s) you might check out first (i.e., which one might have
the 'problem device' on it). More information on this matter is
available on the troubleshooting
severe switch problems web page.
- Clearing port counters
CatOS: clear counters x/y (where x is
the card number and y is the port number)
IOS: clear counters interface "gig or faste"x/y
(where x is the card number and y is the port
number)
- Showing the updated counters
CatOS: show counters x/y (where x is
the card number and y is the port number)
IOS: show counters interface "gig or faste"x/y delta
(since last cleared)
Port Error Logging on a Switch
If a switch port performs poorly, do the following to save the port
information for later use
- Login to the Switch (telnet Switch Name)
Win2K Example: Start->Run->type telnet xxx.xxx.xxx.xxx
(where xxx.xxx.xxx.xxx is the switch's ip address)
- Begin a log file to save the session results
Win2K Example: Terminal->Start
Logging->"Look in" = c:\, "File Name" = log Date Switch Name.txt
(where Date is in the MMDDYY format and Switch Name
is the name of the switch)
Example: log040898ml-16c-c1-es.txt
- Retrieve the switch's time
CatOS: show time
IOS: show clock
- Retrieve the switch's log
CatOS: show logging buffer
IOS: show log
- Retrieve the port information
CatOS: show port x/y (where x is the
card number and y is the port number)
IOS: show interface status "gig or faste"x/y
(where x is the card number and y is the port
number)
- Retrieve the MAC level information on the port
CatOS: show mac x/y (where x is the
card number and y is the port number)
IOS: show int "gig or faste"x/y counters (where
x is the card number and y is the port number)
- Retrieve the switch's time again
- Retrieve the port information again
- Retrieve the MAC level information on the port again
- Stop the log file to save the file's contents
Win2K Example: Terminal->Stop Logging
- Perform steps 1-11 again after 24 hours and save the results
- If the error counts have changed between the two sets of results,
check the patch cables at either end. If the patch cables are OK,
contact NETS by using a "Work Request" and send the results or contact
someone in the section depending on the severity of the problem.
Show the Status and VLANs Connected to a
Switch
- Login to the Switch (telnet Switch Name)
- Show the Status of the VLANs
CatOS: show vlan
IOS: show vlan
The last section of this status display shows the VLAN configuration
information. Please review the on-line documentation to understand the
column terms.
Show the VLAN Trunking on a Switch
- Login to the Switch (telnet Switch Name)
- Show the Status of the trunking
CatOS: show trunk
IOS: show interfaces trunk
(Please review the fields descriptions on the Cisco web for
descriptions of each field.)
Show Modules and Software Versions for a
Switch
- Login to the Switch (telnet Switch Name)
- Show the Status of the modules
CatOS: show module
IOS: show module
Show the Software Versions and Memory
Information for a Switch
- Login to the Switch (telnet Switch Name)
- Show the version information
CatOS: show version
IOS: show version
Show the Switch Error Log
- Login to the Switch (telnet Switch Name)
- Show the error log
CatOS: show logging buffer
IOS: show log
Error Logging on a Switch
If a switch performs an unscheduled reboot, do the following to save
the reboot information
- Login to the Switch (telnet Switch Name)
Win2K Example: Start->Run->type telnet xxx.xxx.xxx.xxx
( where xxx.xxx.xxx.xxx is the switch's ip address)
- Begin a log file to save the session results
Win2K Example: Terminal->Start
Logging->"Look in" = c:\, "File Name" = log Date Switch Name.txt
(where Date is in the MMDDYY format and Switch Name
is the name of the switch)
Example:: log040898ml-16c-c1-es.txt
- Retrieve the switch's time
CatOS: show time
IOS: show clock
- Retrieve the switch's log
CatOS: show logging buffer
IOS: show log
- Retrieve the switch's version information
CatOS: show version
IOS: show version
- Retrieve the switch's installed modules information
CatOS: show module
IOS: show module
- Retrieve the switch's current configuration
CatOS: show config
IOS: show run
- Stop the log file to save the file's contents
Win2K Example: Terminal->Stop Logging
- Archive the error log
General host and phone access port
Most ports on the UCAR network will be configured for host and phone
access. When a switch or module is added, the established default port
configurations are applied.
These include:
- spanning-tree portfast default (global)
- spanning-tree portfast bpduguard default (global)
- switchport
- switchport mode access
- switchport voice vlan <xxx>
- wwr-queue cos-map x x x (QOS priority mapping)
- mls qos vlan-based
- spanning-tree guard root
To define a port for use at least 2 things need to be configured -
the port description and the access vlan
- description <this is the location info>
- switchport access vlan <xxx>
copy run start (don't forget to save your changes)
Access point configuration
There are a few configurations that are slightly different than the
general host and phone access port configuration. One of those is a
port configuration for an access point. There is one command that
should be removed from our established defaults, and a couple of
additions.
To remove a command, use the no form:
Then add these:
- switchport trunk encapsulation dot1q
- switchport mode trunk
- switchport trunk native vlan <xxx> (defined vlan for the
campus APs)
- switchport trunk allowed vlan <xxx,xxx,xxx,xxx> (a set of
vlans for the various campus wireless services)
Don't forget to save your changes.
Configuration for connecting
Non-NETS switches
Another port configuration would be to connect a port to a Non-NETS
switch or a switch that belongs to a division. There are a few required
commands that must be configured on the port to protect the UCAR
network from problems associated with loops and broadcast storms. A
Non-NETS switch will only have a single connection to the UCAR network.
- spanning-tree portfast disable
- spanning-tree bpduguard disable
- switchport trunk encapsulation dot1q
- switchport mode trunk
- switchport trunk allowed vlan <xxx,xxx,xxx,xxx>
Don't forget to save your changes.
Modifying a port
assignment on a switch
- Login to the Switch (telnet Switch Name)
- If the port is being disabled, set the VLAN to 1. Otherwise,
check the Subnet and VLAN
list to determine the VLAN to use.
- Verify the VLAN exists on the switch via the "show vlan" command.
This is the output from a good vlan:
y2k-6509> (enable) show vlan 1000
VLAN Name Status IfIndex Mod/Ports, Vlans
---- -------------------------------- --------- ------- ------------------------
1000 example-net active 235 6/1
15/1
VLAN Type SAID MTU Parent RingNo BrdgNo Stp BrdgMode Trans1 Trans2
---- ----- ---------- ----- ------ ------ ------ ---- -------- ------ ------
1000 enet 101000 1500 - - - - - 0 0
VLAN MISTP-Inst DynCreated RSPAN
---- ---------- ---------- --------
1000 - static disabled
- Once the existence of the VLAN has been verified on the switch,
proceed to activating the port:
CatOS: set vlan z x/y (where z is the
vlan number, x is the card number and y is the port
number)
IOS: interface "gig or faste"x/y (where x
is the card number and y is the port number)
switchport access vlan z (where z is the vlan
number)
- Change the name of the port to the opposite end's connection
device, usually a telecommunications outlet
CatOS: set port name x/y ML-43A-W1-2B (where x
is the card number and y is the port number, and the text is
the information on the connection)
IOS: interface "gig or faste"x/y (where x
is the card number and y is the port number)
description ML-43A-W1-2B (the text is the information on the connection)
Download a Switch's Configuration
from the TFTP Server
NOTE: This procedure will disrupt the switch's operation!!!
- Login to the Switch (telnet Switch Name)
- Download the configuration file (configure HostIPAddress Directory/File
- where HostIPAddress is the TFTP host, Directory/File
is the directory and configuration name)
CatOS: configure xxx.xxx.xxx.xxx
configs/fl2-2143-c1-es
IOS: copy tftp xxx.xxx.xxx.xxx1
configs/fl2-2143-c1-es running-config
( where xxx.xxx.xxx.xxx is the tftp server
address)
This will take a few minutes and each configuration line will be
displayed on the console
Enabling/Disabling system messages from
displaying in the current session
- If you are troubleshooting a problem on a switch and you keep
getting interrupted by lots of system messages scrolling by, you can
issue this command to turn them off for the duration of your session
CatOS: set logging session disable
IOS:
terminal no monitor
- And of course if you do want to see those messages again, you'd
enter "set logging session enable"
CatOS: set logging session enable
IOS: terminal monitor
Deleting one arp entry on a switch
- How do you clear an individual ARP cache entry on the router
should you need to?
CatOS: clear arp xxx.xxx.xxx.xxx
IOS: clear ip arp xxx.xxx.xxx.xxx
General Notes for Switch/Card
Installations
- Check that all needed hardware is available (Cards, cables, patch
panels, cable management, rack screws)
- Schedule Down Time and send an Outage Notice at least a week in
advance
- Prepare a Complete Check List of items needed for the
installation
Example:
- Get three 48 port cards
- Get six patch panels
- Get 24 card to patch panel cables
- Bring tool bag
- Get rack screws
- Bring PC & console cables
- Bring port assignment sheets
- Get Fluke OneTouch
- Bring Labeling doc. & labeler
- Bring this document
- During the installation, test all ports with the OneTouch
- Install at least the generic labels on all devices and patch
panels
Initial Switch Setup & Installation
Check List
- Install the switch with correct power & cable management
- Connect a console device to the console port
- Login to the switch's console port by entering the password [if
one has already been assigned--if not, there won't be one!]
- Change the security mode to modify the configuration (enable Password)
- Clear the switches configuration
CatOS: clear config all
IOS: delete nvram:startup-config
reload
- Verify the switch is running the current IOS version [can be
upgraded via flash card, or via minimal TCP/IP config if necessary]
- If not, perform the download procedure
- Set the switch's unique information
- Set the name (where Switch Name is the name of the
switch)
CatOS: set system name fl2-2143-c1-gs
set prompt fl2-2143-c1-gs>
IOS: hostname fl2-2143-c1-gs
- Set the VLAN domain
CatOS: set vtp domain ucarvtp
set vtp mode off vlan
set vtp mode off mst
IOS: vtp domain ucarvtp
vtp mode transparent
- Set the switch IP address
CatOS: set interface sc0 vlan-number xxx.xxx.xxx.xxx
yyy.yyy.yyy.yyy
IOS: interface vlan-number
ip address xxx.xxx.xxx.xxx yyy.yyy.yyy.yyy
no ip redirects
no ip proxy-arp
no ip route-cache
no shut
(where vlan-number is the management VLAN number for the
campus, xxx.xxx.xxx.xxx is the IP address of the switch, and yyy.yyy.yyy.yyy
is the mask)
- Define the default route for the switch
CatOS: set ip route 0.0.0.0 xxx.xxx.xxx.xxx
IOS: ip route 0.0.0.0 xxx.xxx.xxx.xxx
(where xxx.xxx.xxx.xxx is the IP address of the default router)
- Define the radius information for the security login to the
device
CatOS: set radius server xxx.xxx.xxx.xxx
auth-port 1816 primary
set radius key abcdefghijklmnop123456
set radius attribute framed-ip-address include-in-access-req enable
IOS: radius-server host xxx.xxx.xxx.xxx
auth-port 1816 acct-port 1818
radius-server source-ports 1645-1646
radius-server retransmit 1
radius-server timeout 3
radius-server key abcdefghijklmnop123456
ip radius source-interface Loopback0
(where xxx.xxx.xxx.xxx is the IP address of the radius server
and abcdefghijklmnop123456 is the system key )
- Follow the card installation procedures below to configure any
installed modules
- Set the login methods to use radius
CatOS: set authentication login radius enable console
primary
set authentication login radius enable telnet primary
set authentication enable radius enable console primary
set authentication enable radius enable telnet primary
IOS: aaa authentication login default group radius line
aaa authentication enable default group radius enable
aaa authorization console
aaa authorization exec default group radius none
- Set the login password
CatOS: set password a1b2c3d4
IOS: line con 0
password 0 a1b2c3d4
transport preferred none
(get a1b2c3d4 from security file)
- Set the enable password
CatOS: set enablepass z9y8x7w6
IOS: enable secret 0 z9y8x7w6
service password-encryption
(get z9y8x7w6 from security file)
- Configure SNMP settings
CatOS: set snmp community read-only xxxxxxxx
set snmp community read-write xxxxxxxx
set snmp community read-write-all xxxxxxxx
IOS: snmp-server community xxxxxxx RO 95
snmp-server community xxxxxxx RW 95
snmp-server community public xxxxxxx RO 97
(where xxxxxxxx is the appropriate NCAR SNMP community
strings from security file)
- Enable time synchronization from the network
CatOS: set ntp broadcastclient enable
set timezone MST -7 0
set summertime enable MDT
set summertime recurring second Sunday March 02:00 first Sunday
November 02:00 60
IOS: clock timezone MNT -7
clock summer-time MDT recurring
ntp server xxx.xxx.xxx.xxx
- Enable DNS
CatOS: set ip dns server xxx.xxx.xxx.xxx primary
set ip dns server yyy.yyy.yyy.yyy (for the secondary)
set ip dns enable
set ip dns domain ucar.edu
IOS: ip domain-name ucar.edu
ip name-server xxx.xxx.xxx.xxx
ip name-server yyy.yyy.yyy.yyy (for the secondary)
Card Installation Procedures
- Actions Before Card is Inserted
- Get card and if needed cables, patch panels, and cable
management
- Login to switch to check software levels to verify card will
be supported and the switch is at the current version levels
- Schedule Down Time and send an Outage Notice at least a week
in advance (the switch may crash or need to be reset)
- Produce labeling for card
- If needed, download new software to switch
- Actions at Time of Card Insertion
- Login to the switch through the console port with a PC
- Check switch status (show vlan, show trunk, show port)
- Prepare patch panel and cables if needed
- Install the card (This may reboot the switch)
- a card insertion message should appear
- Verify the status of the new module
CatOS: show text x
show module
IOS: show diganostic result module x
show module
- Connect the cables to the card and secure
- Issue the following commands for a module being used for end
host connection.
CatOS
- set port host <mod>/1-48
- set port qos <mod>/1-48 trust trust-cos
- set port qos <mod>/1-48 vlan-base
- set port auxiliaryvlan <mod>/1-48 <campus
V-VLAN> cdpverify enable
- set port jumbo <mod>/1-48 enable (if this is a
1Gig capable module)
- set errordetection packet-buffer <mod>
powercycle
Issuing the 'set port host' command achieves the same result as if you
had entered each of the following commands separately: 'set spantree
portfast', 'set trunk off', and 'set channel mode off'. You should do
this for all 10/100/1000 ports on all Cisco Catalyst 6500s that you
know have only single hosts connected. This solves many potential
problems we have seen with hosts (e.g., appletalk problems)
IOS
- interface range "gig or faste"<mod>/1-48
- switchport
- switchport mode access
- switchport voice vlan <campus V-VLAN>
- mls qos vlan-based
- mtu 9216 (if this is a 1Gig capable module)
- wrr-queue cos-map 3 3 3 (if this is a WS-X6148A
module)
- no shut
- exit
- error-detection packet-buffer action module
<mod> reset
- Label the installed components (card, cables, patch panels)
Adding a Network (IP subnet)
These are the steps you need to go through in order to add a
network (new IP subnet):
- Check the Subnet
and VLAN list to determine the VLAN to use
Choose an unused number, preferably one "next" to an existing number
for the customer
- The master-network-list file may be incorrect, so you need to
verify that the given number is not in use.
Log in to a router and use a show ip route 128.117.x.0
command, where x is the network number.
The router will display information about the route.
-- If the first line says Routing entry for 128.117.0.0/16,
then there is no explicit route to the network, and it's not in use.
-- If the first line says anything else, then the route is probably in
use, and you should try to allocate a different subnet number.
- Add the network to the NND Network Information using the NND's Django
Administrative Interface.
NOTE: network name should always end in "net".
- Determine whether the network will be at the ML, FL, or CG site.
Use the appropriate devices for the campus.
- ML: mlra
mlrb (ml-243b-c1-gs)
- CG: cgra
cgrb (cg1-0103-c1-gs)
- FL: flra
flrb (fl4-1012-c1-gs)
- Add router interfaces for the new network
(in this example, the addition of a new ML network is shown along with
our current 'standard' interface settings; the important things to
note are:
- the 'a' router gets a .253 interface address and the 'b' router
gets a .254 interface address
- the 'a' router gets a
'101' priority value and the 'b' router defaults to a '100' value
- the standby IP address is the same for each
on mlra:
int vlan241
description --------------------------------------- VLAN 241 (ad1testnet)
ip address 128.117.241.253 255.255.255.0
no ip redirects
no ip proxy-arp
ip pim sparse-dense-mode
ip cgmp
ntp broadcast
standby 1 ip 128.117.241.251
standby 1 priority 101
standby 1 preempt
standby 1 authentication Auth
on mlrb:
int vlan241
description --------------------------------------- VLAN 241 (ad1testnet)
ip address 128.117.241.254 255.255.255.0
no ip redirects
no ip proxy-arp
ip pim sparse-dense-mode
ip cgmp
ntp broadcast
standby 1 ip 128.117.241.251
standby 1 preempt
standby 1 authentication Auth
Also be sure to do a 'no shutdown' on each of these new
interfaces after you've defined them (but before you exit configuration
mode); then exit configuration mode and do a
'copy run start'; also note the ip addresses you assigned as
part of that last step -- you'll need those numbers to make the DNS
request in the next step.
Determine whether you want the the interface to be OSPF passive
(on both routers) or not. Our new default is passive-interface, so you
only need to specify something here (e.g.,
"no passive-interface Vlan2" ) if you want it to *not* be
passive.
- Submit a DSG work request for the DNS part of this--you'll
request a DNS entry for each of the following:
- the 'a' router interface; continuing the example above,
you'd ask for 'mlra-n241.ucar.edu' for 128.117.241.253
- the 'b' router interface; continuing with the example above,
you'd ask for 'mlrb-n241.ucar.edu' for 128.117.241.254
- the network 'default gateway' (router address for nodes
on the new network) address; continuing with the example above, you'd
ask for 'mlr-n241.ucar.edu' for 128.117.241.251
- Add the new VLAN to all the switches on the campus. If you have
access to David Mitchell's Python script named edit-vlan.py on the
nagman machine, you can do something like
~mitchell/bin/edit-vlan.py add
<campus> <vlan id> <vlan name>
to add it for all switches on a campus. If you don't have access to the
script, you'll have to manually apply the Adding a VLAN to a Switch procedure
on each closet switch, and set the STP root manually as described in
the next step.
- If you can't run the edit-vlan.py script, or if it produced
error messages, you should manually set the spanning tree protocol
(STP) root for the VLAN appropriately. For example, if the router
interface for the VLAN is on mlra/b, set the STP root to be on mlra
with these commands on mlra:
configure terminal
spanning-tree vlan <n> priority 8192
end
copy running-config startup-config
Replacing a Supervisor Card
Since we have redundant Supervisors in all of our systems, you only
need to prep the replacement with the proper CatOS or IOS
image. The configuration will be synchronized after insertion in the
switch.
- Insert the replacment module in a test switch
- Connect a terminal or PC to the console port
- Copy the proper image to the Sup using a flash card
copy slot0:cat6000-sup2k9.8-4-5.bin bootflash:
or
copy disk0:s3223-ipbasek9-mz.122-33.SXH4.bin sup-bootdisk:
- Enter the boot statement to use the correct image
set boot system flash bootflash:cat6000-sup2k9.8-4-5.bin prepend
or
boot system flash sup-bootdisk:s3223-ipbasek9-mz.122-33.SXH4.bin
- Reload the supervisor
CatOS: reset system
IOS: reload
- Power down the switch and remove the supervisor from the test
switch
- Remove failed supervisor and replace with configured replacement.
- Verify that the supervisor comes online and that syncronization
happens
Establishing Etherchannel connections
between two ports
Configuring EtherChannels in the Cisco IOS Software is a two-step
process: first the ports are assigned to a channel-group and then the
virtual interface port-channels are configured. The virtual interface
port-channel behaves like a physical interface. In both CatOS and Cisco
IOS, all configurations on the port channel interfaces are propagated
to the physical interfaces of the port channel. For example, shutting
the port channel
interface will shut all physical ports on that port channel. To change
parameters of all ports in an EtherChannel, the configuration should be
applied to the port channel interface. Although the Cisco IOS Software
allows configuration on physical interfaces, the configuration will not
be propagated to the port channel bundle. If the interfaces within the
bundle are not identical, the channel will not form.
EtherChannels in CatOS and Cisco IOS Software bundle individual
Ethernet links into a single logical link to provide bandwidth
aggregation and link resilience in a network. Catalyst 6500 Ethernet
interfaces support up to eight interfaces per EtherChannel with all
interfaces at the same speed: 10,100, 1000 or 10,000 Mbps.
Ports do not have to be contiguous or on the same module, however,
the following conditions must be met for the etherchannel to work:
- Ports can form an EtherChannel when they are in different PAgP
modes as long as the modes are compatible (check documentation for
compatible combinations). The default channel mode for a port is auto.
In this mode, the port will not initiate the creation of a channel, but
will create one if the other end of the link requests it. In
'desirable' mode the port will ask the other end to create a channel,
which will succeed if the other end is either 'auto' or 'desirable'.
The 'off' mode should be used on host connections to reduce the port
startup time. The 'on' mode should never be used as it can
cause spanning tree problems. Normally, host ports should be in 'off'
and trunks should be in 'auto'. If a channel is desired between two
switches, those ports should be manually configured into the same admin
group and mode 'desirable'.
- Ports on a switch can be combined into an EtherChannel when
they are in the same administrative group. Ports on different modules must
be manually configured to the same group if a channel is to form.
- Assign all ports in an EtherChannel to the same VLAN, or
configure them as trunk ports.
- If you configure the EtherChannel as a trunk, configure the
same trunk mode on all the ports in the EtherChannel. Configuring ports
in an EtherChannel in different trunk modes can have unexpected
results.
- An EtherChannel supports the same allowed range of VLANs on
all the ports in a trunking EtherChannel. If the allowed range of VLANs
is not the same for a port list, the ports do not form an EtherChannel
even when set to the auto or desirable mode with the set port channel
command.
- Ports with different port path costs, set by the set spantree
portcost command, can form an EtherChannel as long they are otherwise
compatibly configured. Setting different port path costs does not, by
itself, make ports incompatible for the formation of an EtherChannel.
- Do not configure the ports in an EtherChannel as dynamic VLAN
ports. Doing so can adversely affect switch performance.
- An EtherChannel will not form with ports that have different
GARP VLAN Registration Protocol (GVRP), GARP Multicast Registration
Protocol (GMRP), and quality of service (QoS) configurations.
- Configure all ports in an EtherChannel to operate at the same
speed and duplex mode.
- An EtherChannel will not form with ports where the port
security feature is enabled.
- You cannot enable the port security feature for ports in an
EtherChannel.
- An EtherChannel will not form if one of the ports is a SPAN
destination port.
- An EtherChannel will not form if protocol filtering is set
differently on the ports.
- Enable all ports in an EtherChannel. If you disable a port in
an EtherChannel, it is treated as a link failure and its traffic is
transferred to one of the remaining ports in the EtherChannel.
Some notes on EtherChannel:
Date: Thu, 9 Oct 2003 11:07:12 -0600 (MDT)
From: David Mitchell
To: Pete Donnie Sakosky
Cc: ne@ucar.edu
Subject: Re: etherchannel pain in the ---
Here's my understanding for setting up etherchannel.
- Every port is in a channel admin group by default. These are
high numbered groups of four adjancent ports on a card.
- We want the admin groups to be like numbered ports on two
different cards, such as 3/3,4/3. I've been using the port numer for
the group number. So for ml-50-c1-gs, you should just need to do a
"set port channel 3/4,4/4 4" on ml-mr-c1-gs. On the
closet switch, a similar command is needed
"set port channel 1/1,2/1 1". These commands will bounce
all affected ports.
- Once the admin group has been created, the configurations of
the ports needs to match for the channel to form. The command
"show channel group 4 info" will list the status of
all relevant config settings. And mis-match in the output of this will
keep the channel from forming. Usually this is just the qos settings.
- The output of 'show channel' will show the actively
channelling ports. Note that the "channel Id" is an arbitrary
number that gets assigned to active channels. No idea why they don't
just use the admin group numbers.
-David
-------- Original Message -------- Subject:
Re: EMERGENCY SERVICE MAINTENANCE: ML-50-C1-GS
Date: Thu, 09 Oct 2003 09:08:22 -0600
From: Pete Donnie Sakosky
To: Jeff Custard
hi jeff,
indeed, there is no etherchannel right now. i was searching
for that QoS setting, so thanks for getting that for me. that was one
of four problems that wouldn't let me bring up the channel. first was a
bad fiber patch, second was the QoS, third was non-matching ISL trunks
on ml-50, and fourth was existing etherchannel configuration on
ml-mr-c1-gs.
i found out how to fix all of this, but i ran out of window,
so i'll have to bring up the channel some other time.
the non-matching ISL trunking was a case of having (on ml-50)
2/1 as negotiate and 1/1 as on. they are both set to "on" now.
the existing etherchannel configuration was tougher to figure
out and is what blew the thing this morning. on ml-mr, both 3/4 and 4/4
(which correspond to ml-50 2/1 and 1/1 respectively) were already in
separate port channel groups. i found out the hard way that there is no
"clear port channel 3/4" command. to remove ports and
delete existing channel groups, you need to remove all ports in a
channel group-
"set port channel x/x-y,x/x mode off". this is
non-intuitive and not cool. it also impacts the spanning tree of those
other ports in that channel group. i knocked ml-16 off the network for
30 seconds while spanning tree reconverged (but it was within our
window).
so, as of now, ports 3/4 and 4/4 on ml-mr are finally not
associated with any channel groups. since you got the QoS, here's all
that should be needed to bring up etherchannel now-
on ml-mr-c1-gs:
set port channel 3/4,4/4 mode desirable silent
other than that, the OS upgrade was smooth. this was a simple
7P's breakdown with the etherchannel stuff. i'll get it fixed on
saturday it sounds like.
donnie
- Some Cisco URLs for etherchannel:
http://www.cisco.com/warp/public/473/#EtherChannel
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/sft_6_1/configgd/channel.htm
Document revision history:
- James Van Dyke - February 11, 1999 - Version 3.0
- Pete Siemsen - May 4, 1999 - Version 3.1
- Pete Siemsen - January 05, 2001 - Version 3.2
- Jeff Custard - April 13, 2001 - Version 3.3
- Pete Siemsen - April 26, 2001 - Version 3.4
- David Mitchell - May 30, 2001 - Version 3.5
- Jeff Custard - August 03, 2001 - Version 3.6
- Pete Siemsen - September 28, 2001 - Version 3.7
- Pete Siemsen - October 12, 2001 - Version 3.8
- Jeff Custard - November 01, 2002 - Version 3.9
- Jeff Custard - April 11, 2002 - Version 4.0
- Jeff Custard - September 09, 2002 - Version 4.1
- Jeff Custard - December 18, 2002 - Version 4.2
- David Mitchell - February 9, 2004 - Version 4.3
- Belinda Housewright - September 29, 2004 - V4.4 - New Remedy form
for Adding/Removing switch
- Pete Siemsen - Novemberber 8, 2004 - V4.5
- Paul Dial- Novemberber 18, 2005 - V4.6
- Teresa Shibao - February 23, 2006 - V4.7
- Teresa Shibao - July 7, 2006 - V4.8
- Pete Siemsen - September 6, 2006 - V4.9
- Teresa Shibao - August 23, 2007 - V5.0
- Teresa Shibao - August 5, 2009 - V5.1
- Teresa Shibao - September 3, 2009 - V5.2 Adding IOS command
equivalents
- Teresa Shibao - November 6, 2009 - V5.3 additional notes for show
and clear counters, CatOS and IOS
- Teresa Shibao - September 23, 2010 - V5.4 added QOS config when
adding new 1G module
- Teresa Shibao - November 2, 2010 - V5.5 added typical
configuration examples
- Pete Siemsen - September 19, 2011 - V5.6 updated Cisco
syntax in the "Adding a Network" section
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