EtherChannel and HSRP

7/25/2019 EtherChannel and HSRP

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Chapter 21© 2007 – 2010, Cisco Systems, Inc. All rights reserved. Cisco P!lic

Con"igring #in$

Aggregation %ith&therchannel




EtherChannel Technology

'p to ( physical lin$s can !e !ndled

into a single logical &therChannellin$.

'sally &therChannel is sed "or

trn$ lin$s.

Con"igration applied to port channelinter"ace a""ects all physical

inter"aces assigned to the port

channel.

#oad !alancing ta$es place !et%eenthe physical lin$s in an &therChannel.

&therChannels can !e #2 or #)

inter"aces.



Chapter 2)© 2007 – 2010, Cisco Systems, Inc. All rights reserved. Cisco P!lic

EtherChannel Management Protocols Port Aggregation Protocol (PAgP) is a Cisco*proprietary protocol that aids in

the atomatic creation o" +ast &therChannel lin$s. -hen an &therChannel lin$ is con"igred sing PAgP, PAgP pac$ets are sent !et%een

+ast &therChannel*capa!le ports to negotiate the "orming o" a channel.

-hen PAgP identi"ies matched &thernet lin$s, it grops the lin$s into an &therChannel. Spanning

tree adds the &therChannel as a single !ridge port.

Link Aggregation Control Protocol (LACP) is part o" an I&&& speci"ication(02.)ad/ that also ena!les several physical ports to !e !ndled together to

"orm an &therChannel.

#ACP ena!les a s%itch to negotiate an atomatic !ndle !y sending #ACP pac$ets to

the peer.

It per"orms a similar "nction as PAgP %ith Cisco &therChannel.

ecase #ACP is an I&&& standard, yo can se it to "acilitate &therChannels in

mied*s%itch environments. In a Cisco environment, !oth protocols are spported.




PAgP Modes

Mode Purpose

Auto Places an inter"ace in a passive negotiating state in %hich the inter"ace responds to thePAgP pac$ets that it receives !t does not initiate PAgP negotiation de"alt/.

Desirable Places an inter"ace in an active negotiating state in %hich the inter"ace initiates negotiations%ith other inter"aces !y sending PAgP pac$ets. Inter"aces con"igred in the 3on4 mode donot echange PAgP pac$ets.

On +orces the inter"ace to channel %ithot PAgP.

on!silent I" a s%itch is connected to a partner that is PAgP*capa!le, con"igre the s%itch inter"ace "ornon*silent operation. 5he non*silent $ey%ord is al%ays sed %ith the ato or desira!lemode. I" yo do not speci"y non*silent %ith the ato or desira!le mode, silent is assmed.5he silent setting is "or connections to "ile servers or pac$et analy6ers this setting ena!lesPAgP to operate, to attach the inter"ace to a channel grop, and to se the inter"ace "or

transmission.




LACP Modes

Mode Purpose

Passi"e Places a port in a passive negotiating state. In this state, the port respondsto the #ACP pac$ets that it receives !t does not initiate #ACP pac$etnegotiation de"alt/.

Acti"e Places a port in an active negotiating state. In this state, the port initiatesnegotiations %ith other ports !y sending #ACP pac$ets.

On +orces the inter"ace to the channel %ithot PAgP or #ACP.




Con#iguring EtherChannel $tep %& Speci"y the inter"aces that %ill compose the &therChannel grop. 'sing the range

commands ena!les yo to select several inter"aces and con"igre them all together. A

good practice is to start !y shtting do%n these inter"aces, so that incompletecon"igration %ill not start to create activity on the lin$:

Switch(config)# interface range interface_type [interface_range]

$tep '& Speci"y the channeling protocol to !e sed. 5his command is not applica!le to all

Catalyst plat"orms. ;o can also speci"y the channeling protocol at Step ):

Switch(config-if-range)# channel-protocol {pagp | lacp}

$tep & Create the port*channel inter"ace, i" necessary, and assign the speci"ied inter"aces

to it:

Switch(config-if-range)# channel-group number mode {active | on | {auto

[non-silent]} | {desirable [non-silent]} | passive

$tep & Speci"y the port*channel inter"ace. -hen in the inter"ace con"igration mode, yo

can con"igre additional parameters. 5he physical inter"aces %ill inherit these parameters.

-hen this con"igration is complete, yo can reena!le the physical ports in the

&therChannel !ndle:

Switch(config)# interface port-channel number

Switch(config-if)# interface parameters


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E*ample+ EtherChannel Con#iguration

Switch(config)# interface fastethernet 0/23

Switch(config-if)# channel-group 2 mode activeSwitch(config)# interface fastethernet 0/24

Switch(config-if)# channel-group 2 mode active

Switch(config)# interface port-channel 2

Switch(config-if)# sitchport mode trun!

Switch(config-if)# sitchport trun! native "#$% &&

Switch(config-if)# sitchport trun! alloed "#$% 2'3'&&

<emote S%itch con"igration

RSwitch(config)# interface fastethernet 0/23RSwitch(config-if)# channel-group ( mode on

RSwitch(config)# interface fastethernet 0/24

RSwitch(config-if)# channel-group ( mode on

RSwitch(config)# interface port-channel (

RSwitch(config-if)# sitchport mode trun!

RSwitch(config-if)# sitchport trun! native "#$% &&



(© 2007 – 2010, Cisco Systems, Inc. All rights reserved. Cisco P!lic

,eri#ying EtherChannel (%)

;o can se several commands to veri"y an &therChannel

con"igration. =n any physical inter"ace mem!er o" an &therChannel

!ndle, the sho interfaces interface_id etherchannel

command provides in"ormation on the role o" the inter"ace in the

&therChannel.

Inter"ace +ast&thernet 0>2 !elo% is part o" &therChannel !ndle 1.

5he protocol "or this &therChannel is #ACP.

Switch# sho interfaces fa0/24 etherchannel

Port state = Up Sngl-port-Bndl Mstr Not-in-Bndl

Channel grop = ! Mode = "ctie $cchange = -

Port-channel = nll $C = - Psedo port-channel = Po!

Port inde% = & 'oad = &%&& Protocol = '"CP



?© 2007 – 2010, Cisco Systems, Inc. All rights reserved. Cisco P!lic

,eri#ying EtherChannel (')

5he sho etherchannel number port-channel command can

!e sed to display in"ormation a!ot a speci"ic port*channel. elo% Port*channel 1 consists o" t%o physical ports, +a0>2) and

+a0>2.

It ses #ACP in active mode.

It is properly connected to another s%itch %ith a compati!le

con"igration.5his is %hy the port*channel is said to !e in se.

Switch# sho etherchannel ) port-channel

Port-channels in the grop

---------------------------

Port-channel Po (Pri*ar+ "ggregator)

"ge of the Port-channel = !,d&.h!&*//s

'ogical slot0port = &0! N*1er of ports = 2

Port state = Port-channel "g-3nse

Protocol = '"CP

Ports in the Port-channel

3nde% 'oad Port 4C state No of 1its

------5------5--------5--------------5-----------

& fa&02. "ctie /

! / fa&02/ "ctie /




,eri#ying EtherChannel ()

-hen several port*channel inter"aces are con"igred on the same device, the

sho etherchannel summar* command is se"l "or displaying one*line

in"ormation per port*channel.

As sho%n !elo% the s%itch has three &therChannels con"igred: @rops 2 and

7 se #ACP and @rop ? ses PAgP. &ach &therChannel has the mem!er

inter"aces listed. All three grops are #ayer 2 &therChannels and are all in se

$- net to the port*channel nm!er/.

Switch# sho etherchannel summar*

6lags 7 - down P - 1ndled in port-channel

3 - stand-alone s - sspended

8 - 8ot-stand1+ ('"CP onl+)

R - 'a+er. S - 'a+er2

U - in se f - failed to allocate aggregator

M - not in se9 *ini** lin:s not *et

- nsita1le for 1ndling

w - waiting to 1e aggregatedd - defalt port

N*1er of channel-grops in se 2

N*1er of aggregators 2

$rop Port-channel Protocol Ports

------5-------------5-----------5--------------------------------------------

2 Po2(SU) '"CP g&0/,(P) g&0&(P) g&0!(P) g&02(P)

Po(SU) '"CP g&0/(P) g&0/;(P)

, Po,(SU) P"gP g&0;(P) g&0,(P)




,eri#ying EtherChannel ()

5he sho running-config interface

interface_id command displays sections o" yorcon"igration relevant to &therChannel. 5he inter"ace

argment can !e physical or logical.

Switch# sho running-config interface g0/4+

Bilding configration<<<Crrent configration !/ 1+tes

interface $iga1it4thernet&0/;

switchport access lan /!

switchport trn: encapslation dot!

switchport *ode trn:

channel-grop *ode actie

Switch# sho running-config interface port-channel ,

Bilding configration<<<

Crrent configration ,2 1+tes

interface Port-channel

switchport trn: encapslation dot!

switchport *ode trn:




EtherChannel Load .alancing




EtherChannel Load .alancing E*ample ere the &therChannel load*!alancing mechanism is con"igred to se

sorce and destination IP address pairs. 5his rle is applied to IPv and IPv9 tra""ic, %hereas the non*IP load*

!alancing mechanism ses sorce and destination BAC address pairs.

It %as o!served that %ith sorce*destination IP load !alancing, the

!alancing ends p more li$e 70*)0 on the lin$s

Switch(config)# port-channel load-balance src-dst-ip

Switch(config)# eit

Switch# show etherchannel load-1alance

4therChannel 'oad-Balancing Configrationsrc-dst-ip

4therChannel 'oad-Balancing "ddresses Used Per-Protocol

Non-3P Sorce >?R 7estination M"C address

3P/ Sorce >?R 7estination 3P address

3P@ Sorce >?R 7estination 3P address




'nderstanding

+irst op<edndancyProtocols




/ntroduction to 0irst 1op 2edundancy

Proy A<P

Static De"alt @ate%ay

S<P

E<<P

@#P




Pro*y A2P

#egacy soltion.

&na!led !y de"alt.

'sed !e"ore de"alt

gate%ays %ere spported

on IP clients.

&nd station acts as i"destination %ere on same

net%or$ segment.

<elatively slo% de to

reliance on aging ot o" A<P cache.




$tatic De#ault 3ate4ay

Fot dynamic.

Does not providesecondary path.



Chapter 21(© 2007 – 2010, Cisco Systems, Inc. All rights reserved. Cisco P!lic

1ot $tandby 2outer Protocol (1$2P)

Cisco*proprietary gate%ay

redndancy protocol. Participating roters tal$ to

each other and agree on a

virtal roter %ith a virtal

IP address %hich endsystems se as a de"alt

gate%ay.



Chapter 21?© 2007 – 2010, Cisco Systems, Inc. All rights reserved. Cisco P!lic

1$2P 0ailo"er

-hen active roter or lin$s

!et%een roters "ail, thestand!y roter stops

seeing hello messages

"rom active roter. Stand!y

roter then assmes roleo" "or%arding roter.

ecase ne% "or%arding

roter assmes !oth IP

and BAC address o"

virtal roter, end stations

see no disrption in

service.




1$2P Operation

S<P active and stand!y roters send hello messages to

mlticast address 22.0.0.2 'DP port 1?(8. ello messages sed to commnicated !et%een roters

%ithin S<P grop.

All roters in S<P grop need to !e #2*adGacent.

All roters in an S<P grop have speci"ic roles andinteract in speci"ic %ays:

,irtual router

Acti"e router

$tandby router Other routers




1$2P MAC Address

<oter A assmes the active role and "or%ards all "rames

addressed to the assigned S<P BAC address o"

5555&5c56&ac**, %here is the S<P grop identi"ier.




1$2P $tates$tate De#inition

Initial 5he !eginning state. 5he initial state indicates that S<P does notrn. 5his state is entered via a con"igration change or %hen aninter"ace "irst comes p.

#isten 5he roter $no%s the virtal IP address, !t the roter is neither theactive roter nor the stand!y roter. It listens "or hello messages"rom those roters.

Spea$ 5he roter sends periodic hello messages and actively participatesin the election o" the active or stand!y roter. A roter cannot enterspea$ state nless the roter has the virtal IP address.

Stand!y 5he roter is a candidate to !ecome the net active roter andsends periodic hello messages. -ith the eclsion o" transient

conditions, there is, at most, one roter in the grop in stand!ystate.

Active 5he roter crrently "or%ards pac$ets that are sent to the gropvirtal BAC address. 5he roter sends periodic hello messages.-ith the eclsion o" transient conditions, there mst !e, at themost, one roter in the active state in the grop.




1$2P $tate Transition

<oter A starts. As it is the "irst roter "or stand!y @rop 1 in the s!net,it transits throgh the listen and spea$ states and then !ecomes the

active roter.

<oter starts a"ter <oter A. -hile <oter is in listen state, <oter A

is already assming the stand!y and then the active role. As there is

already an eisting active roter, <oter assmes the stand!y role.




1$2P Acti"e 2outer and $panning Tree Topology

In a redndant spanning*tree topology, some lin$s are !loc$ed. 5he spanning*

tree topology has no a%areness a!ot the S<P con"igration. 5here is no

atomatic relationship !et%een the S<P active roter election process and theSpanning 5ree <oot ridge election.

-hen con"igring !oth spanning tree and S<P or any other "irst hop

redndancy protocol/, yo mst ma$e sre that the active roter is the same as

the root !ridge "or the corresponding E#AF. -hen the root !ridge is di""erent

"rom the S<P active roter, a s!optimal path can reslt, as illstrated.




Con#iguring 1$2P Con"igre S<P on the inter"ace.

Switch(config-if)#

standb* group-number ip ip-address

5he grop nm!er is optional and indicates the S<Pgrop to %hich this inter"ace !elongs.

Speci"ying a niHe grop nm!er in the stand!y

commands ena!les the creation o" mltiple S<P grops.

5he de"alt grop is 0.

5he IP address is that o" the virtal roter IP address "or the

S<P grop.




Con#iguring 1$2P Priority and Preempt 5o set the S<P priority vale o" a roter, enter this command in

inter"ace con"igration mode:standb* group-number priorit* priority-value

5he priority vale can !e "rom 0 to 288. 5he de"alt vale is 100.

Dring the election process, the roter %ith the highest priority in an

S<P grop !ecomes the active roter. I" a tie occrs, the roter %ith

the highest con"igred IP address !ecomes active. I" the roters do not have preempt con"igred, a roter that !oots p

signi"icantly "aster than the others in the stand!y grop !ecomes the

active roter, regardless o" the con"igred priority. 5he "ormer active

roter can !e con"igred to resme the "or%arding roter role !y

preempting a roter %ith a lo%er priority. 5o ena!le a roter to resme the "or%arding roter role, enter this

command in inter"ace con"igration mode:

standb* [group-number A preempt [dela* minimum seconds reload

seconds s*nc secondsA




1$2P Con#iguration E*ample

<oters A and are con"igred %ith priorities o" 110 and ?0,

respectively. 5he con"igration o" <oter A is displayed. 5he preempt $ey%ord ensres that <oter A %ill !e the

S<P active roter as long its inter"ace is active.

Roter"(config)# interface vlan )0

Roter"(config-if)# ip address )0.).).2 2((.2((.2((.0

Roter"(config-if)# standb* )0 ip )0.).).)

Roter"(config-if)# standb* )0 priorit* ))0

Roter"(config-if)# standb* )0 preempt



Chapter 22(© 2007 – 2010, Cisco Systems, Inc. All rights reserved. Cisco P!lic

1$2P Authentication E*ample S<P athentication prevents roge roters on the net%or$ "rom Goining

the S<P grop. S<P athentication is ena!led !y con"igration o" anathentication string on all mem!er devices o" the S<P grop.

5he athentication string is a maimm o" ( characters and the de"alt

$ey%ord is cisco.





Roter"(config-if)# standb* )0 preempt

Roter"(config-if)# standb* )0 authentication *)23



Chapter 22?© 2007 – 2010, Cisco Systems, Inc. All rights reserved. Cisco P!lic

1$2P Timer Considerations and Con#iguration

,ariable Description

group-number =ptional/ @rop nm!eron the inter"ace to %hichthe timers apply.5he de"alt is 0.

msec =ptional/ Interval inmilliseconds. Billisecond

timers allo% "or "aster "ailover.

hellotime ello interval in seconds.5his is an integer "rom 1throgh 288. 5hede"alt is ) seconds.

holdtime 5ime, in seconds, !e"orethe active or stand!yroter is declared to !edo%n. 5his is an integer"rom 1 throgh 288. 5hede"alt is 10 seconds.



Chapter 2)0© 2007 – 2010, Cisco Systems, Inc. All rights reserved. Cisco P!lic

1$2P Timers Con#iguration E*ample





Roter"(config-if)# standb* )0 preemptRoter"(config-if)# standb* )0 authentication *)23

Roter"(config-if)# standb* )0 timers msec 200 msec ,(0

Roter"(config-if)# standb* )0 preempt dela* minimum 22(




1$2P ,ersions S<P version 1 is the de"alt in I=S and it ena!les grop nm!ers p to 288.

ecase one can have p to 0?8 E#AFs, one has to rese the same S<P grop

nm!er on mltiple inter"aces i" needed. 5his is allo%ed even thogh it might casesome con"sion.

S<Pv1 ses the Eirtal BAC address o" the "orm 0000.0C07.AC J S<P

grop/, and the S<Pv1 hello pac$ets are sent to mlticast address 22.0.0.2.

S<P version 2 has !een added to I=S since 12.2 9S& or later and it ena!les

grop nm!ers p to 0?8. 5his ena!les yo to se the E#AF nm!er as the gropnm!er.

-ith S<Pv2, the BAC address o" the virtal roter and the mlticast address "or

the hello messages has !een changed. 5he virtal BAC address is

0000.0C?+.+ JS<P grop/, and hello pac$ets are sent to mlticast

address 22.0.0.102.

Also, S<Pv2 has a di""erent pac$et "ormat "rom S<Pv1. &nsre that the sameversion is con"igred on all roters in a S<P grop. =ther%ise hello messages are

not nderstood. Eersion 1 is the de"alt.

'se the "ollo%ing command to change the version:

Switch(config-if)# standb* hsrp group number > version 2




1$2P /nter#ace Tracking (%)

&na!les priority o" stand!y grop roter to !e atomatically

adGsted !ased on availa!ility o" trac$ed inter"aces.

-hen trac$ed inter"ace !ecomes navaila!le, S<P priorityis decreased.

&nsres the roter %ith navaila!le inter"ace relinHishes

active roter role.



Chapter 2))© 2007 – 2010, Cisco Systems, Inc. All rights reserved. Cisco P!lic

1$2P /nter#ace Tracking (') Con"igre inter"ace trac$ing.

Switch(config-if)

standb* [group-number ] trac! interface-type interface-

number [interface-priority ]

,ariable Description

group-number =ptional/ Indicates the grop nm!er on the inter"ace to%hich the trac$ing applies. 5he de"alt nm!er is 0.

interface-type Indicates the inter"ace type com!ined %ith the inter"acenm!er/ that %ill !e trac$ed.

interface-

number Indicates the inter"ace nm!er com!ined %ith the inter"acetype/ that %ill !e trac$ed.

interface-

priority =ptional/ Indicates the amont !y %hich the hot stand!ypriority "or the roter is decremented %hen the inter"ace!ecomes disa!led. 5he priority o" the roter is incremented!y this amont %hen the inter"ace !ecomes availa!le. 5hede"alt vale is 10.




1$2P /nter#ace Tracking ()

5o con"igre S<P %ith inter"ace trac$ing, "ollo% these steps:

Step 1. Con"igre the stand!y grop.

Step 2. Con"igre priority de"alt 100/. Step ). Con"igre preempt on all devices %ithin the S<P grop.

Step . Con"igre the trac$ed inter"aces and decrement de"alt

decrement 10/.



1$2P /nter#ace Tracking ()

SD/(config)# interface vlan )0

SD/(config-if)# ip address )0.).).2 2((.2((.2((.0

SD/(config-if)# standb* )0 ip )0.).).)

SD/(config-if)# standb* )0 priorit* ))0

SD/(config-if)# standb* )0 preempt

SD/(config-if)# standb* )0 trac! fastethernet0/23 20

SD/(config-if)# standb* )0 trac! fastethernet0/24

Documents

EtherChannel and HSRP