Configuring site to site redundancy on dual Metro Ethernet

[beaugreen]

Hi everyone,

I am checking in to see if anyone has configured a dual Metro Ethernet (2 different ISPs) to both sites that have 2 ISR routers (4431 and 4321) and stack switches (3850 and nexus 5548)?  Right now it is working with a single router on both ends but the company wants to make sure all hardware are redundant.  The problem I have is one router will have the voice LAN card and the other is not.  I am thinking the GLBP is out since we'll have voice traffic issue.

The option I am thinking about is use the layer 2 switches to connect the Metro E lines and trunk the VLANs up to both routers and use HSRP to run active / standby.

any help will be appreciated..

thanks  

[balaji.bandi]

HSRP to run active / standby - with IP SLA is recomended setup.

[beaugreen]

Hi BB,

With this setup, will STP be an issue?  I am attaching a topology so you can get a better understanding of my network.  Also can I do LACP on the edge of the CE switches?

thanks

[balaji.bandi]

yes if the end to end L2, you have to consider STP loops and proper planning.

ISP1 and ISP2 are L3, then your setup is ok, as Per HLD we see and asusme here to L2.

[beaugreen]

I am contacting the ISP1 and 2 to check if LACP is supported.  ISP 2 responded saying LACP should work but if not call them for troubleshoot.  ISP 1 has not respond yet.

Is there another way to make this work? 

I know that connecting both metro-e to L3 will work with the GLBP but the issue I have here is the voice traffic which will not build on the one of the router.  So the only way I see is through the L2 switches and LACP them so I can use sub-interfaces on the routers and HSRP / IP SLA.  The only problem is STP may cause an issue.

Thanks

[beaugreen]

HI BB,

I have reached out to ISP 1 and they are not doing LACP.  So I changed the design, please see the attachment.

Will this work?

[balaji.bandi]

yes on the high level looks ok, if you think STP is the issue, use different STP priorty on each side, so if one link failover other will take over the traffic.

what is the ISR 4K role here ?

[beaugreen]

Hi BB,

ISR 4K routers are the collection points for either sides.  So this is like a headquarter to a Branch office connection.

Please correct me if I am wrong.  For the STP issue, I am using different VLANs to hide both connections from each other so no loop can be created.  I also want to utilize both connections to work simultaneously and not active / passive.

Active / standby will happen on the network devices and not the ISP connections. 

thank you for your help.

[balaji.bandi]

" I am using different VLANs to hide both connections from each other so no loop can be created"

How, can you exaplain ? as per my understanding these are L2 Links right ? (or L3 links - if iam wrong correct me)

as per diagram it show as L2.

[beaugreen]

Hi BB,

Each ISP connection at the CE has VLAN assigns to them (VL3000 and VL2000).  Now both VLANs destination is the L3 routers sub-interfaces.  So this would be like a router on a stick connection where the data exchange will be at L3 routers.

Is this make sense?

thanks

[balaji.bandi]

L3 Part is OK, But link failure how you going to handle, 

I would not suggest to have access port each end, that is not the right way to do it.

take example each  port you have allocated to access vlan 2000 and Vlan3000, If VLAN 3000link fails, how will VLAN 2000 will alloow VLAN 3000 ?

These link need to be Trunk and allow VLAN 2000  and VLAN 3000.

you can make STP Priority as below :

Salem side :

spanning-tree vlan 2000 priority 24576

spanning-tree vlan 3000 priority 28672

 Wilsonville side :

spanning-tree vlan 3000 priority 24576

spanning-tree vlan 2000 priority 28672

[beaugreen]

Hi BB,

I see what you meant, but I have no control over the Metro Ethernet hand off from 2 different ISP.  Are you saying to tag the ports where ISP1 and 2 are connecting to the switch? 

I contacted ISP1 since they are using tag EVC on one end of the connection but not the other.  They advise me to use the tag number and not allow another VLAN since they will drop it.

What I can do is make my side more redundant.  Please check the attachment.

BB, please let me know if I really answer you question on your last post.

thanks

[balaji.bandi]

If you do not have any control over the link, i can only think of for your solution is traffic engineering, based on the availability link and pass the traffic.

is this live setup or you going to build one ? do you have any configuration put place to test ?

[beaugreen]

Hi BB,

Right now the network connection is showing on the attachment and it works.  I am to re-design my network connection (both side) to be redundancy.  2 routers, 2 stack switches.  But you have to know that one of the router will not have voice traffic but the current one will still have it.

that is why I am using HSRP and not GLBP.  I want the router with voice traffic to be the primary and if something goes wrong with it or the switch above it, it will flip to the other router that has no voice configuration in it.

Let me know it this make sense.

thank you

[balaji.bandi]

High level agreed, but again, learning lessons is very important while deploying and noted and the changes to fix easy solution like roleback plan in place if any issue encounter after desing change.