11-28-2006 12:17 AM - edited 03-03-2019 02:49 PM
how can i apply the failover concept, if i have customer connected to a 3750 switch and two uplinks that are pointing to two different networks. the customer gateway points to the first uplink, how can the other uplink send the customer's traffic to the internet if the first uplink failed?
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11-28-2006 01:53 AM
If you have 3 of these 3750's. You can have a hub and spoke topology. Like this
Use 3750 A for client connectivity
Use 3750 B for say ISP 1 with one of the host connected to it.
use 3750 C for ISP 2 and have a trunk between 3750B and 3750C with the SVI's configured.
So 3750 A is connected to 3750B and 3750C on routed port.
On 3750 a Put you client on vlan1 and create a SVI for it. Put the ports connected to 3750B and 3750 C on a routed port
On 3750A
Conf t
ip routing
int vlan 1
ip address 1.1.1.1 255.255.255.0
no shut
int fa 0/1
no switchport
ip address 2.2.2.1 255.255.255.0
no sh
int fa 0/2
no switchport
ip address 3.3.3.1 255.255.255.0
ip route 0.0.0.0 0.0.0.0 2.2.2.2
ip route 0.0.0.0 0.0.0.0 3.3.3.2 200
On 3750 B :->
Conf t
ip routing
int vlan 2c--> Connect your PC on Vlan2
ip address 11.11.11.1 255.255.255.0
no shut
int fa 0/1
no switchport
ip address 2.2.2.2 255.255.255.0
no sh
int fa 0/2 -> trunk to 3750C
switchport encapsulation do1tq
switchport mode trunk
ip route 1.1.1.0 255.255.255.0 2.2.2.1
ip route 1.1.1.0 255.255.255.0 11.11.11.2
On 3750 C :->
Conf t
ip routing
int vlan 2
ip address 11.11.11.2 255.255.255.0
no shut
int fa 0/1
no switchport
ip address 3.3.3.2 255.255.255.0
no sh
int fa 0/2 -> trunk to 3750B
switchport encapsulation do1tq
switchport mode trunk
ip route 1.1.1.0 255.255.255.0 3.3.3.1
ip route 1.1.1.0 255.255.255.0 11.11.11.1
Once that is done and you are pinging from the host on 3750 A to host on 3750B, go ahead and disconnect the cable between 3750A and 3750B, the traffic should pass through 3750C.
HTH,
-amit singh
11-28-2006 12:24 AM
Hi Sawsan,
When you say 2 different networks you mean 2 different subnets? The 2 Uplinks are connected to different subnets on 2 different routers?
Ankur
11-28-2006 12:41 AM
Hi ankbhasi,
yes, for example, the first uplink (213.42.87.0), the second uplink (80.17.60.0)on two different routers
11-28-2006 12:56 AM
Hi Sawsan,
Instaead of defining a gateway can we have 2 static routes pointing to 2 different address with second one having higher admin distance.
Something like this
ip route 0.0.0.0 0.0.0.0
ip route 0.0.0.0 0.0.0.0
In this case when first link goes down the second static route will take the action.
Regards,
Ankur
11-28-2006 01:34 AM
how can I test this concept and prove it, if i'm having 3 of Cisco 3750?
11-28-2006 01:51 AM
Hi Swasan,
If this 3750 working as a complete layer 2 switch? or you are using it as a layer 3 edge for customer?
Ankur
11-28-2006 01:53 AM
If you have 3 of these 3750's. You can have a hub and spoke topology. Like this
Use 3750 A for client connectivity
Use 3750 B for say ISP 1 with one of the host connected to it.
use 3750 C for ISP 2 and have a trunk between 3750B and 3750C with the SVI's configured.
So 3750 A is connected to 3750B and 3750C on routed port.
On 3750 a Put you client on vlan1 and create a SVI for it. Put the ports connected to 3750B and 3750 C on a routed port
On 3750A
Conf t
ip routing
int vlan 1
ip address 1.1.1.1 255.255.255.0
no shut
int fa 0/1
no switchport
ip address 2.2.2.1 255.255.255.0
no sh
int fa 0/2
no switchport
ip address 3.3.3.1 255.255.255.0
ip route 0.0.0.0 0.0.0.0 2.2.2.2
ip route 0.0.0.0 0.0.0.0 3.3.3.2 200
On 3750 B :->
Conf t
ip routing
int vlan 2c--> Connect your PC on Vlan2
ip address 11.11.11.1 255.255.255.0
no shut
int fa 0/1
no switchport
ip address 2.2.2.2 255.255.255.0
no sh
int fa 0/2 -> trunk to 3750C
switchport encapsulation do1tq
switchport mode trunk
ip route 1.1.1.0 255.255.255.0 2.2.2.1
ip route 1.1.1.0 255.255.255.0 11.11.11.2
On 3750 C :->
Conf t
ip routing
int vlan 2
ip address 11.11.11.2 255.255.255.0
no shut
int fa 0/1
no switchport
ip address 3.3.3.2 255.255.255.0
no sh
int fa 0/2 -> trunk to 3750B
switchport encapsulation do1tq
switchport mode trunk
ip route 1.1.1.0 255.255.255.0 3.3.3.1
ip route 1.1.1.0 255.255.255.0 11.11.11.1
Once that is done and you are pinging from the host on 3750 A to host on 3750B, go ahead and disconnect the cable between 3750A and 3750B, the traffic should pass through 3750C.
HTH,
-amit singh
11-28-2006 03:22 AM
thanks for both of you,
and thanks amit for the configuration..i will try to configure it and see the results.
11-28-2006 03:28 AM
Hi,
If you have two links connecting on the same router,then the solution to send the traffic to other link when one fails is to put a static route with some higher metric.e.g
ip route 0.0.0.0 0.0.0.0 x.x.x.x 200
where x.x.x.x is the next hop ip address.
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