backuplink-urgent

[alsayed]

Hi ALL!

I have 2 sites connected 2gather(6509 in each site); HO;OFFICE1.the primary link between HO & office1 its laser LINK 1gig;the second link (backup) it is wireless connection 5m;THE Routing protocol in the enterprise is EIGRP.i need to achieve load balance and redundancy when the primary link goes down (laser) the backup link(wireless) will takes over. I need the highs priority on the laser link. Also when the primary link become available. The traffic should be rerouted on the first one.

How can I achieve this implementation? Configuration on each side very much appreciated?PS Have a look to the topology that i;ve attached

10xs for ur help

Ali

[amit-singh]

Hi Friend,

Make sure that you have you all the desired interfaces included under the EIGRP and running on them. EIGRP does both equal cost and unequal cost load-balacning. If it is setup correctly, It will provide you load-balancing and redundancy.

If its the unequal cost metric that EIGRP is getting from the other links, you might have to use " variance " command under the EIGRP to do the load-balancing.

Conf t

router eigrp 1

network x.x.x.x y.y.y.y

network a.a.a.a b.b.b.b

varience 2

Please check the link below for more help :

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094820.shtml

HTH, Please rate if it does.

-amit singh

[alsayed]

amit 10xs for ur reply!

q1:but what about when the primary link become available.the eigrp automaticaly restore the trraffic?what happend?

q2:WE DON'T NEED ROUP MAP LIKE IF WE RUN BGP;

HAVE A LOOK TO THE CONFIG AND COORECT ME IF I;M MISTAKED:

OFFICE 1

INT GIG3/1

DESC LASER LINK 1 GIG TO HO

IP ADDRESS 192.168.100.1 255.255.255.252

INT GIG3/2

DESC WIRLESS LINK TO HO(BACKUP)

IP ADDRESS 192.168.101.2 255.255.255.252

!

ROUTER EIGRP 100

NETWORK 100.100.0.0 0.0.255.255

NETWORK 192.168.0.0 0.0.255.255

VARIANE 2

[alsayed]

HI

ALSO WHAT ABOUT THE REDANDANCY IF THE PRIMARY LINK GOES DOWN.& HOW THE BACKUP TAKES OVER IN MY SITUATION

10XS

[amit-singh]

Hi,

1. If primary link fails, EIGRP will start routing the packets via your secondry link automatically, if it has the other route as a feasible successor in its topology table. You can check it using " show ip eigrp topology "

2. No, you dont have to use route maps in this config. Your config seems to be OK.

Please paste " show ip eigrp topo " from your switches and let us have look to confirm it and see if it has another route in its table.

HTH,

-amit singh

[alsayed]

HI AMIT 10XS FOR UR HELP!

BUT U DIDN'T TELL ME WHAT ABOUT IF THE PRIMARY LINK BECOME AVAILABLE WHAT HAPPENIG TO THE WIRLESS LINK.HOW IS THE PROCCESS TO REROUTE TRAFFIC VIA THE PRIMARY

10XS AMIT

[alsayed]

hi

do i need ip CEF in my setup.what is the benefits if i issue this command

10xs for ur help

[amit-singh]

Hi,

You can have your CEF configured, which is Cisco expree forwarding. You can use the CEF to have your load-balancing work for you as well.

http://www.cisco.com/en/US/products/hw/modules/ps2033/prod_technical_reference09186a00800afeb7.html

http://www.cisco.com/en/US/products/sw/iosswrel/ps1824/products_feature_guide09186a0080087adc.html

HTH,

-amit singh

[alsayed]

HI AMIT 10XS FOR UR REPLY!

I JUST NEED TO USE THE WIRLESS LINK AS BACKUP.I DONT NEED TO USE IT ; UNLESS IF THE PRIMARY LINK GOES DOWN.IN THIS CASE WHAT IS THE EFFECT OF CEF HERE IN MY SETUP

10XS

[devang_etcom]

Ali,

it will use for load balancing as well as when you are having lots of over head or you can say higher cpu usage then you can use CEF and also provid fast switching.

[alsayed]

HI ALL

WHAT IS THE EFFECT OF THIS COMMAND:

VARIANCE 2.DID U USED BECAUSE WE HAVE 2 LINLK

10XS

[devang_etcom]

hi ali,

lets say you are having mulitple path connectd to destination...for example we are having 4 different route to destination of materics

path 1:1100

path 2:1100

path 3:2000

path 4:4000

now if you want to go for the load balancing and if you use variance 2 then path 1, path 2 and path 3 will participate in to the load balancing and when ever you are going to use variance 4 then all four path will used for load balancing.

hope this helps you

regards

Devang

[devang_etcom]

it mean varianc 2 will not include only two path but it include all the path whose materics is less then the 1100*2=2200...

it means it is not depend on links its depends on matrics after multiplication

if you are having three link with matrics like 10,15,19 and if you use variance 2 then it will include all the three paths because 10*2=20 and all the link is having matrics less then the 20.

regards

Devang