Configure 3G wireless as a backup line with layer 3 cisco switch??

[Fida jlassi]

Hi all,

We have an existing GPRS modems to tranfer data between 2 different sites, This connection is a little bit slow at no more than about 114kbps, the idea is to add a 3G modem, so the solution will be based on a dual communication lines which are the 3G network and GPRS network.

The GPRS line will be the primary and the 3G will be secondary, This redundancy will offer a high level of communication availability between both sites.

is it possible to configure this redundancy with a cisco switch layer 3? if it's the case did you have a tutorial or a link that describe how to do this work with a layer 3 ciso switch?

any information will be helpful for me, thanks

[cadet alain]

Hi,

if the modem were layer 3 devices that accept to nat non directly connected subnet then it could be working with a switch but I don't know the syntax for the CLI on SF300. you would have to track primary like explained, be sure that your IP SLA is sourced from primary with PBR and on each modem have a route back to the internal subnet.

Regards

Alain

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[Fida jlassi]

Hi,

Yes I am using the phoenix PSI-MODEM-3G/ROUTER which accepts the nat configuration.

But now Can anyone help me with the commands or with the web interface to do this configuration?

Regards,

Jlassi Fida

[Fida jlassi]

Hi all,

Can anyone help me with the architecture above? Exactly how to configure the layer 3 switch? and if the SF300 can do this work?

Regards,

Jlassi Fida

[Fida jlassi]

No answer

[Fida jlassi]

Is there anyone that can help with this?

[cadet alain]

Hi,

This is a Cisco forum not a phoenix forum so we can't give you the configuration for non Cisco devices.

Regards

Alain

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[Fida jlassi]

Hi,

The modem/Routers are phoenix but the layer 3 switch is a Cisco Switch, and I need your on how to configure the cisco switch to support the failover between the two routers.

Regards,

Jlassi Fida

[cadet alain]

Hi,

your switch is a small business switch so you should ask in this forum.

Regards

Alain

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[Fida jlassi]

So could you help me with this, and tell me if it's possible to configure the SF300 to support the failover between the two routers? and how?

[cadet alain]

Hi,

I just took a quick look at the configuration guide and I don't see any tracking feature available but you can have floating routes indeed.So it would only work if modem/router connected interface goes down or it is shutdown then the line protocol of the switch interface would be down and the floating static route would get installed.

http://www.cisco.com/en/US/docs/switches/lan/csbms/sf30x_sg30x/administration_guide/78-19308-01.pdf

Regards

Alain

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[Fida jlassi]

Hi Cadet Alain,

Could you please explain more how it will works and give us an example with the command line for the cisco switch

Regards,

Jlassi Fida

[Fida jlassi]

Hi,

I used the floating static route like you suggest, but the problem is with the Cisco switch SF300 when we create the VLANs and put the Interface's IP address  to the PC gateway the Communication will be established between the VLANs created in the switch.

So should I isolate the Vlans before configuring the floating routes, because in the case of the 2 interfaces are ok they will send data in the same time !!

Regards,

Jlassi Fida

[cadet alain]

Hi,

I don't understand your query, what do you mean ?

Regards

Alain

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[Fida jlassi]

Hi,

I created the Vlans in the cisco small business switch then I put IP address of the inside interface to the gateway of the computer in the inside network, the result is I was able to ping from this PC to the 3G and the GPRS routers, so even without configuring the static floating routes the data passthrough the two interfaces.

So what can I do in this case? the data will be received from the two lines GPRS and 3 G and there is no balancing between the two lines.

NB:the floating static route that I used is like described below:

ip route 0.0.0.0 0.0.0.0

ip route 0.0.0.0 0.0.0.0 200

Regards,

Jlassi Fida

[cadet alain]

Hi,

first you should configure next-hop for static routes and not outgoing interface, I'm really surprised it is working this way (it means your routers have proxy-arp enabled and this is a security issue).

Then if you specified a higher AD for second route(floating route) then it shouldn't be inserted in the routing table and so you shouldn't be able to communicate through it to go out the internet.

pinging from the switch to both is normal because they are both directly connected to your switch.

now if you configure the second static route with same AD as first then your switch will load share the traffic but I don't know how this models do load sharing, if it is like other platforms then it is src-dst ip based load shared meaning all traffic from a source to a destination will use same link always.

Regards

Alain

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