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Chapter 21© 2007 – 2010, Cisco Systems, Inc. All rights reserved. Cisco P!lic
Con"igring #in$
Aggregation %ith&therchannel
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Chapter 22© 2007 – 2010, Cisco Systems, Inc. All rights reserved. Cisco P!lic
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$s in an &therChannel.
&therChannels can !e #2 or #)
inter"aces.
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Chapter 2)© 2007 – 2010, Cisco Systems, Inc. All rights reserved. Cisco P!lic
EtherChannel Management Protocols Port Aggregation Protocol (PAgP) is a Cisco*proprietary protocol that aids in
the atomatic creation o" +ast &therChannel lin$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.
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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.
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Chapter 28© 2007 – 2010, Cisco Systems, Inc. All rights reserved. Cisco P!lic
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.
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Chapter 29© 2007 – 2010, Cisco Systems, Inc. All rights reserved. Cisco P!lic
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 "#$% 2'3'&&
<emote S%itch con"igration
RSwitch(config)# interface fastethernet 0/23RSwitch(config-if)# channel-group ( mode on
RSwitch(config)# interface fastethernet 0/24
RSwitch(config-if)# channel-group ( mode on
RSwitch(config)# interface port-channel (
RSwitch(config-if)# sitchport mode trun!
RSwitch(config-if)# sitchport trun! native "#$% &&
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,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
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,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 /
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,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)
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,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 $iga1it4thernet&0/;
switchport access lan /!
switchport trn: encapslation dot!
switchport *ode trn:
channel-grop *ode actie
Switch# sho running-config interface port-channel ,
Bilding configration<<<
Crrent configration ,2 1+tes
interface Port-channel
switchport trn: encapslation dot!
switchport *ode trn:
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EtherChannel Load .alancing
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Chapter 21)© 2007 – 2010, Cisco Systems, Inc. All rights reserved. Cisco P!lic
EtherChannel Load .alancing E*ample ere the &therChannel load*!alancing mechanism is con"igred to se
sorce and destination IP address pairs. 5his rle is applied to IPv and IPv9 tra""ic, %hereas the non*IP load*
!alancing mechanism ses sorce and destination BAC address pairs.
It %as o!served that %ith sorce*destination IP load !alancing, the
!alancing ends p more li$e 70*)0 on the lin$s
Switch(config)# port-channel load-balance src-dst-ip
Switch(config)# eit
Switch# show etherchannel load-1alance
4therChannel 'oad-Balancing Configrationsrc-dst-ip
4therChannel 'oad-Balancing "ddresses Used Per-Protocol
Non-3P Sorce >?R 7estination M"C address
3P/ Sorce >?R 7estination 3P address
3P@ Sorce >?R 7estination 3P address
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Chapter 21© 2007 – 2010, Cisco Systems, Inc. All rights reserved. Cisco P!lic
'nderstanding
+irst op<edndancyProtocols
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Chapter 218© 2007 – 2010, Cisco Systems, Inc. All rights reserved. Cisco P!lic
/ntroduction to 0irst 1op 2edundancy
Proy A<P
Static De"alt @ate%ay
S<P
E<<P
@#P
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Chapter 219© 2007 – 2010, Cisco Systems, Inc. All rights reserved. Cisco P!lic
Pro*y A2P
#egacy soltion.
&na!led !y de"alt.
'sed !e"ore de"alt
gate%ays %ere spported
on IP clients.
&nd station acts as i"destination %ere on same
net%or$ segment.
<elatively slo% de to
reliance on aging ot o" A<P cache.
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Chapter 217© 2007 – 2010, Cisco Systems, Inc. All rights reserved. Cisco P!lic
$tatic De#ault 3ate4ay
Fot dynamic.
Does not providesecondary path.
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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.
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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.
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Chapter 220© 2007 – 2010, Cisco Systems, Inc. All rights reserved. Cisco P!lic
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
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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.
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Chapter 222© 2007 – 2010, Cisco Systems, Inc. All rights reserved. Cisco P!lic
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.
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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.
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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.
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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.
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Chapter 229© 2007 – 2010, Cisco Systems, Inc. All rights reserved. Cisco P!lic
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
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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
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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)# 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
Roter"(config-if)# standb* )0 authentication *)23
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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.
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1$2P Timers Con#iguration E*ample
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 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(
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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
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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.
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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.
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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/.
7/25/2019 EtherChannel and HSRP
http://slidepdf.com/reader/full/etherchannel-and-hsrp 35/35
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