Redundancy of community routes is a really essential facet of community communication. Routes will be realized statically or dynamically and normally static route is assigned the next administrative distance and fewer preferable than a dynamic route and static route is just not used.
Nonetheless, within the occasion dynamic route is misplaced attributable to any motive corresponding to poor hyperlink or connectivity, jitter, loss and many others. then static route can take over and visitors will be routed by way of an alternate route. So mainly, a static route is a backup route and can solely seem within the routing desk when a dynamically realized route is just not out there or misplaced.
As we speak we glance extra intimately about floating static routes, their professionals and cons and learn how to configure floating static routes.
What’s Floating Static Route?
A floating static route acts as a backup of a dynamic route on the router. The floating static route must be configured with excessive administrative distance with respect to the dynamic route for which it’s appearing as backup. In Cisco Administrative distance (AD) of a static route is 1 as it’s the most reliable connection after the immediately related route with administrative distance (AD) of zero (0). Floating static routes will be mixed with dynamic routes to supply a backup mechanism.
Professionals and Cons of Floating Static Route
PROS
- It makes use of much less bandwidth than dynamic routes
- No CPU cycles are used to calculate or replace routing info
- Higher administrative management over routing
- Static routes will not be marketed within the community therefore are safer
CONS
- Each time community modifications happen you might want to manually reconfigure static routes
- Guide effort is concerned
- Not appropriate for dynamic and complicated community environments
How does Floating Static Route work?
We are going to use a situation to know how a floating static route works and its configuration.
Within the above diagram Router 1 is related with two WAN hyperlinks.
- Gigabit Ethernet hyperlink utilizing OSPF
- T1 line with static routing
Major hyperlink is Gigabit Ethernet utilizing OSPF is a dynamic routing protocol and T1 static route is backup hyperlink in case main turns into unavailable. IOS will select and calculate route having the bottom administrative distance. The slower T1 static route is the popular route based mostly on administrative distance of worth ‘1’. OSPF has an administrative worth of 110 and static route administrative worth is to be manually configured at increased worth and fewer preferable then OSPF dynamic route having administrative worth of 110.
So long as main hyperlink is on the market and OSPF on router 1 learns a route for 192.178.2.0/24 community with default administrative distance of 110 it’ll ignore static route.
Router 1# ip route 192.178.2.0 255.255.255.0 192.178.3.1 130
Use present ‘ip route’ command to confirm if administrative distance of static route is modified increased to administrative route for OSPF.
Router 1# present ip route static
! Legend omitted for brevity
192.178.0.0/16 is variably subnetted, 6 subnets, 2 masks
S 192.178.2.0/24 is immediately related, Serial0/0/1
Router 1# present ip route 192.178.2.0
Routing entry for 192.178.2.0/24
Identified by way of “static”, distance 130, metric 0 (related)
Routing Descriptor Blocks:
* immediately related, by way of Serial0/0/1
Route metric is (0), visitors share rely is (1)
The executive distance of the static route is modified to 130 which is increased than the executive distance of OSPF which is 110. Which makes it the first and most well-liked route for packet forwarding.
Use case for Floating static routes
- Connectivity to particular community
- Connectivity to stub router
- Routing desk entries summarization to scale back dimension of routing commercials
- Act as backup hyperlink within the occasion main hyperlink fails
