reg:l3 to l2 acceses

Answered Question
May 1st, 2007

Dear sir,

One of my customer is having main offce in bombay and branch office in hyderabad he was having 2 lines each line is 2mbps .now his headoffice he was having 3560 (L3)switch and branch office he was having catlyst express-500(ce-500 24tt).now he was connected 2 lines in l3 switch .now he was asking redundancy(i.e if one link gets down automatically next line has to up .now is it possible to do the redundancy from l3 to l2 switch.if it is possible give me some examples.and also he want both side communication.if it is not possible how can i go through this.

Regards

srinivas.D

+91 9246571397

I have this problem too.
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Correct Answer by Paolo Bevilacqua about 9 years 8 months ago

Good, so once you verify that spanning tree is working correctly you have redundancy, then as I said you can see if you can make ether channel work.

Note that unless you can make the latter, the 2nd circuit does not do anything, this is due to the choice or bridging that is always wrong with WAN, with routing you could use the two circuit as one for more speed and performance.

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Paolo Bevilacqua Tue, 05/01/2007 - 04:22

Hi,

Do the 2mbps lines come with serial interface or the provider has installed a router with ethernet ? do these line provide internet access too or are just leased lines ?

vasuramnet Tue, 05/01/2007 - 04:42

Dear bevilacqua,

Thanks for ur reply yes it was each line is 2mbps and provider has inistalled connector cum router having ethernet out.so he was having 2 connevertors each connevertor having 2mbps link that 2 links terminated on normal switch now he was asking redundancy between the two links.now l3 to l2 is possible on trunking.plz help me

Regards

srinivas.D

Paolo Bevilacqua Tue, 05/01/2007 - 05:00

Hi, you should ask the provider if they configured the routers for routing, bridging or what, based on that you can decide hot to use the two links.

vasuramnet Tue, 05/01/2007 - 05:23

Dear sir,

That routers r in bridge mode .that two links is one for in use and second for backup.

now he want redundancy if one goes down second will automatically up he was seeing that type of solution

regards

srinivas.D

Paolo Bevilacqua Tue, 05/01/2007 - 06:05

Hi,

first of all you have to verify that STP (bpdu frames) are passed by this bridge so you have spanning tree protocol running between the tow switches. If it does you are set and can look if toy can configure port aggregation and use both links at same time.

If it does not you have to talk with the provider and find a better solution or place you own router on the ce-500 side, configure vlan on ce500 and similarly on 3560.

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vasuramnet Fri, 05/04/2007 - 04:47

Dear sir,

We pass any and all Ethernet Frames including STP BPDU frames in Bridge

mode

Regards

srinivas.d

Correct Answer
Paolo Bevilacqua Fri, 05/04/2007 - 06:21

Good, so once you verify that spanning tree is working correctly you have redundancy, then as I said you can see if you can make ether channel work.

Note that unless you can make the latter, the 2nd circuit does not do anything, this is due to the choice or bridging that is always wrong with WAN, with routing you could use the two circuit as one for more speed and performance.

As a courtesy to those providing answers, please rate all post using the scrollbox below!

vasuramnet Fri, 05/04/2007 - 21:31

Dear sir,

PLz explain me clearly with exampls plz.

Regards

srinivas.D

Paolo Bevilacqua Sat, 05/05/2007 - 02:07

Hello,

the example is your installation. With bridging, when there is more than one link between bridges, all but one are blocked to prevent loops. Routing is more intelligent, and that does not happen.

Thanks for the nice rating and good luck!

vasuramnet Sat, 05/05/2007 - 03:10

Dear sir,

u mean in my network routing is not happened .so now what can i do now sir.

so plz send me any examples how can i route.

Thanks for ur valube cordination.

waiting for ur reply.

Regards

srinivas.D

Paolo Bevilacqua Sat, 05/05/2007 - 03:17

Hello,

if you want to convert to routing, send first here a diagram that includes exactly all devices installed, brand type and configuration, and who owns them, also include all the circuit installed, speed and type of interfaces, ip addresses currently used.

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