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2 -F0/0 as Backup ????

Hi

I have C2621 router with two fast ethernet interface

I want to use These F0/0 interface as backup of each other

How is it possible ???

Thanks

14 REPLIES
Blue

Re: 2 -F0/0 as Backup ????

YES, this is possible.

the best and easiest way is to connect the two FE interfaces to the other device and have a routing protocol such as eigrp or ospf perform the redundancy automatically.

please see the following links for more info eigrp and ospf configuration:

eigrp -

http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_configuration_guide_chapter09186a00800ca762.html

ospf -

http://www.cisco.com/en/US/products/sw/iosswrel/ps1831/products_configuration_guide_chapter09186a00800b3f2b.html

Re: 2 -F0/0 as Backup ????

i would like to say that its all depends on your connectivity... how you use the router... r u using the router for internet connectivity or for your internal network with the routing protocols...

see if you have two connection of ADSL from your provider connected with the both the interface then you can use the static default router with the two different AD...

or if you are using that both ethernet connection for your internal network with routing protocol then you can use like OSPF as well as EIGRP...

so if you explain your requirement in more detail then it will be good for us to give you proper advise

regards

Devang

New Member

Re: 2 -F0/0 as Backup ????

Hi

Thanks for the Ans !!!!

I want to configure this for my private network and i am using for this as i mentioned Cisco-2621 ,,

and Below the router F0/0 i am using C-3750 and it is directly connected .... there is no routing protoclos ... we are using just satatic routes for the Interconntivity.

So its ia just an idea .. and we want to make it more reliable by doing the the FE Backup Links.

Thanks

Re: 2 -F0/0 as Backup ????

yes then you can use that static route with two different AD but make sure if you configure static route with the destination network id then both the static route should have the same destination network in their statment ... same as below:

ip route a.b.c.d subnetmask fasteth0/0(or your ip of the next hop)

ip route a.b.c.d subnetmask fasteth0/1(or netx hop ip address) 10

here you can see that we are using same destination network id but different next hop ipaddress with different AD...

so in normal condition your first route will use as primary and when that route lost then only route with the AD of 10 will come into the picture as back up...

hope this helps you

rate all useful post

regards

Devang

New Member

Re: 2 -F0/0 as Backup ????

Hi

Thanks for the Ans !!!!!

I am little confuse ..........

We have Layer 3 c3750 OK

and above the 3750 we have router 2621 ok

router and switch are directly connetected with each other

Current status ia

SW-PORT-1 is connected to the FE 0

Sw--18 <-------------->Router FE0

Our requirment is or idea is

Sw--18 <-------------->Router FE0

Backup

Sw--19<-------------->Router FE1

We Have default rout on SW 3750 Toward gateway router 2621

Now tell me

Thanks

Re: 2 -F0/0 as Backup ????

okay now will you tell me which kind of porta are on switch which are connected with the switch...it means its layer3 port or layer 2 port...

regards

Devang

Silver

Re: 2 -F0/0 as Backup ????

Seems you treat the 3750 as a L3 switch that I believe the you will use L3 to connect to the 2621. You have to enable one more VLAN in 3750 for the backup connection then use static or dynamic routing protocol to enable it is fine. Due to it is two P2P connection, enable load-sharing is fine.

However, in this case, even if you add one more connection between ONE switch and ONE router, it only provide the port & cable backup and no equipment failure backup. If you have more switch then terminate the backup link to another switch will be better. If there are only two devices, it may not required. Moreover, the processing power of the 2621 and the WAN connection will not able to carry two 100Mbs traffic, so it may not very useful to connect this link. Only if these two links are via two separated physical paths to prevent any physical connection failure then it will be fine.

Hope this helps.

New Member

Re: 2 -F0/0 as Backup ????

Hi

Thanks for the Ans.

As i understand from the above discussion !!!

That there is no need to connect physically router(2621) two FE with the Same switche/ or may be an other switch.. on the same LAN (or same subnet) it just increse the overhaed for router and it increase the procesing power of router........ AM I CORRECT ???? plz verify it.

Thanks once agian.

Silver

Re: 2 -F0/0 as Backup ????

Yes, in theorical, it depends on how much the traffic will be processed in the router and cause the additional CPU loading. In fact, due to the WAN limited the throughput and no matter you enable multiple connections between same router and switch, you will not gain too much benefit. There is only a resiliency cable between two devices.

However, if the router cannot support VLAN trunking but you want the router to carry VLAN routing, then you can connect two cables to the routers and configure two router ports as different subnet, assign different VLAN at the switch then it will be another usage.

Therefore, confirm the actual requirement and justify the effort to implement, operate and maintain the new system then you will have the ans. yourself.

Or please tell us the requirement and reason detail then there may be another story.

Hope this helps.

New Member

Re: 2 -F0/0 as Backup ????

Hi

Thanks for the Ans !!! Once Agian

I am Sending u my network Diagram plz chek and than suggest abut the my Question

Among router We are using DPLC's (E1's)

We have static routs between all my router;a there is no routing Protocols runing . static route currenlty full fill our requiements.

My question was about the LAN as u can see the PIc very clearly now i want to config 2 FE of router as backup of each other. on same switch with in he same subnet ????? Is it possible ???? if possible how can i do it

Thanks for the replying ...

Regards

Re: 2 -F0/0 as Backup ????

what ever i understand form topology is:

you want to configure your one interface of the switch which is connected with the router as a primary and other as backup interface... am i right?

now tell me how switch 1 connected with the router... switch ports connected with router are layer3 or layer 2 port...

reply me

regards

Devang

New Member

Re: 2 -F0/0 as Backup ????

Hi

Thanks for the Ans

Yes ur right!!! that One FE of router be primary and other will be secandary...

Here is confusion what u have asked " switch ports connected with router are layer3 or layer 2 port"

but i am telling that u we are using Layer 3 switces for the GIGABIT speed.

thanks

Re: 2 -F0/0 as Backup ????

layer 3 port means you can assing the IP address to that perticular interface...

so check in sh run is ther any ip address under that switch ports which are connected with the router...

so do one thing if you have same kind of thing...then enter the ip rouitng command on global configuration mode of switch...

then configure the default static route like this...

ip route 0.0.0.0 0.0.0.0 NexthopeIPaddress(router primary interface ipaddress)

in this ip route command enter the primary link's router interface ipaddress.

ip router 0.0.0.0 0.0.0.0 NexthopeIPaddress(router secondary interface ipaddress) 13

in this ip route command enter the secondary link's router interface ipaddress.

hope this will help you

rate this post if it helps

regards

Devang

New Member

Re: 2 -F0/0 as Backup ????

Hi

Thanks we are using it as Layer 2 Switch

there is no IP ont the port of Switche.

Thanks

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