topic Re: VOSS static route overide in ExtremeSwitching (VSP/Fabric Engine)

VOSS static route overide

treese — Wed, 12 Feb 2025 20:13:58 GMT

I have fabric extend to a remote branch with the remote site learning the quad zero ISP default route from the far end location. I setup a static route at the branch end so local users can use the local ISP default route. I have a route-map built so the local default route won't get advertised/redistributed into ISIS.

Here is the problem i'm trying to solve now. If/when the local ISP goes down, I'd like the alternative route (quad zero router from far end) working so the local users will have internet access via the fabric. The current solution to fix this is to remove the static route then the alternative routes pick up.

Thanks for your help

show ip route alternative
DST MASK NEXT VRF/ISID COST FACE PROT AGE TYPE PRF
----------------------------------------------------------------------------------------------------------
0.0.0.0 0.0.0.0 10.x.x.x GlobalRouter 10 353 STAT 0 IB 5
0.0.0.0 0.0.0.0 DCxxxxx-SW01 GlobalRouter 20040 4051 ISIS 0 IASE 7
0.0.0.0 0.0.0.0 DCxxxxx-SW02 GlobalRouter 20040 4051 ISIS 0 IASE 7

Re: VOSS static route overide

EF — Thu, 13 Feb 2025 13:49:17 GMT

Hi,

If the ISP WAN fails the default route may still alive because the next-hop (ISP LAN) is reachable.

I belive that VOSS hasn´t some similiar to route tracking so we solve it running an script over XIQ-SE that test regular some internet IPs (ex.: 8.8.8.8) if it is not rechable, the script connect to VSP and deletes the route.

Any other idea?

Regards

Re: VOSS static route overide

treese — Thu, 13 Feb 2025 19:40:36 GMT

Yes when the direct internet is down the route is still in the table, that is the issue I'm attempting to resolve.

Re: VOSS static route overide

treese — Thu, 13 Feb 2025 21:15:26 GMT

Do you mind sending me the details on your script? Our XIQ-SE lives on the other side of the fabric extend so I'm not certain its the best solution. I'm thinking I may need to change the static routing to a routing protocol and check the preferences.

Re: VOSS static route overide

EF — Fri, 14 Feb 2025 15:35:38 GMT

I think you should are able to reach the mgmt IP of your VOSS throught the FE, your data plain must be diferent from your control plane but I dont have details about your topo.

About the script, sorry, Im not auth to share this info, but keep it mind it´s possible, one more option.

Re: VOSS static route overide

treese — Fri, 14 Feb 2025 20:25:26 GMT

I understand, are you familiar with setting up a local non static route? If I can do this in my lab, i'll remove the static route and have a local route then when it disappears it would hit on the fabric learned route.

Re: VOSS static route overide

EF — Sat, 15 Feb 2025 20:02:08 GMT

Sorry I dont understand/know concept of " local non static route".

A local route is a attached interface, for example a VLAN interface:

I don't understand how can you replace the static default route using this.

Re: VOSS static route overide

WillyHe — Sun, 16 Feb 2025 09:14:43 GMT

Depending on the setup, which is not clear.

Is there only one FE switch in the remote Branch?
Is the local static default route directly to the ISP router or to another internal L3 switch?
Is the ISP router directly connected to the FE switch?

There are several possibilities/solutions, some described below

When the local static default route is directly to the ISP router, then there are two possibilities.

When the IP address of ISP router becomes unreachable then it will become unreachable after the default ARP time-out six hours and the MAIN site branch default route become active.
Optionally the ARP table aging timer can be changed to a low(er) value (e.g. 5 minutes) on the FE switch, be aware this is a global setting on the device.
When the ISP router is directly connected to the FE switch, two options
1. When the link goes down then the MAIN site branch default route become active immediately because the ISP router is cleared from the ARP table.
2. When the ISP router becomes unreachable, then again the ISP ARP entry must time-out.

When there is an internal L3 network between the FE switch and the ISP router, then if a dynamic routing protocol is used in the internal network, the FE switch can be configured to be a member of the internal routing and receives the default route to the ISP which must have a lower cost than the default route from the MAIN branch, then the fail-over depends on the internal network.