ISP Router Redundancy

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Jan 17th, 2009
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I have two ISP link (Redundancy purpose) configured with EIGRP on same router.

But router doesn't having any redundancy.

For that i am looking for HSRP config on two router.But i m confused about physical connectivity.

can any one tell about physical connectivity and config.


Thanx..


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Giuseppe Larosa Sat, 01/17/2009 - 09:07
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Hello Arjun,

the usual setup for your scenario is the following:


you use two routers: R1, R2


ISP link1 is connected to R1

ISP link2 is connected to R2


R1 and R2 share one or more client Vlans and advertise them on EIGRP to the provider on both links.


to get R1 and R2 to share subnets on the internal side you connect R1 Fastethernet (or GE) to a LAN switch and you do the same for R2.


the two LAN links if necessary will carry multiple Vlans (L2 trunks on the switch side).


on the router side the main lan interface has no ip address and Vlan subinterfaces are used


int f0/0

no ip address

int f0/0.10

enc dot1q 10

ip address 10.10.10.2 255.255.255.0

standby 10 ip 10.10.10.1

standby 10 priority 105

standby 10 preempt

standby 10 track interface "WAN side here"


each client Vlan needs at least one HSRP group and you need to use different HSRP group numbers (10 in the example above)


the routers and the HSRP group use 3 addresses: one for each subinterface and one for the VIP


when you configure R2 you just skip the line


standby XX priority 105


this makes R1 the active router for outbound in normal conditions, if the R1's wan link fails all clients will send traffic to R2 that becomes the active router.


if one router fails the other is still able to receive and send traffic.


In some scenarios you can connect the two routers to two different switches in order to achieve fault tolerance to single switch failure.

In this latter case a trunk link between the two switches is needed too. The trunk has to carry all the client Vlans.



Hope to help

Giuseppe




arjunsawant Mon, 01/19/2009 - 01:30
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Hi..


Good Afternoon..

Pls find the attachment for more clarification.I have two more link on same router for my branches.I want backup for my main router.

Sorry for incomplete info.




Attachment: 
pauloroque Sat, 01/17/2009 - 14:22
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Hi Ajunsawant.

Just connect link1 to R1 and link2 to R2. Connect both routers to the same SW (or two SW if you want to make SW redundancy too).

Pick 3 IP addresses on the same subnet: one for R1, one for R2 and one for VIP (a IP address shared by the two routers). Make sure R1 can ping R2. Make sure to config EIGRP on the new router.


---

R1 Config

int f0/0

ip add x.x.x.1 255.255.255.0

standby ip x.x.x.3

---

R2 Config

int f0/0

ip add x.x.x.2 255.255.255.0

standby ip x.x.x.3




pkpatel Mon, 01/19/2009 - 10:17
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Another option would be to configure EIGRP on branch routers and switch. This will allow switch to learn routes dynamically and route accordingly. This will also allow you to load balance.

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