Do we ever configure a static route with AD of 255?
workfrom925
Member Posts: 196
in CCNA & CCENT
As far as the old CCNA cert goes, I hope I'm not going overboard with this question. If an AD of 255 means it's unreachable and can't be believed, do we ever need to configure a route with an AD of 255?
Ex:
R2(config)#ip route 10.55.10.0 255.255.255.0 10.62.21.1 255
Ex:
R2(config)#ip route 10.55.10.0 255.255.255.0 10.62.21.1 255
Comments
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networker050184
Mod Posts: 11,962 Mod
An AD of 255 does not mean the route is unreachable. This is what people usually refer to as a 'floating' static. Since the AD is high it will only be used in the even that a route from your routing protocols or a lower AD static is not present in the table.An expert is a man who has made all the mistakes which can be made. -
darkerz
Member Posts: 431 ■■■■□□□□□□
I use it to float secondary static destinations when I don't have ample CAB / approval process time to make a more complex change.
Configure EIGRP Equal cost load balancing per ip packet on the go on your L3 distro to MPLS edge?
2 weeks.
2 static routes to offload a data domain backup service who's flow is going out one of your two links, saturating the entire end user experience in the company MPLS'ing back to the network for HQ resources?
Simple, low risk, per host*, done.
...
It's not glorious, but sometimes the simple solution is the best until you come up with a detailed, tested, planned complex solution.
~:twisted: -
Dieg0M
Member Posts: 861
As Networker050184 said, 255 does not mean unreachable. It only means that the AD is not trustworthy enough to be added to the routing table. You would use an AD of 255 in a situation where you would like to advertise a summary route without installing it in your local routing table. Since AD is locally significant, the route will only be added in the routing table of the peer router with the default AD of the routing protocol you used.Follow my CCDE journey at www.routingnull0.com -
workfrom925
Member Posts: 196
networker050184 wrote: »An AD of 255 does not mean the route is unreachable. This is what people usually refer to as a 'floating' static. Since the AD is high it will only be used in the even that a route from your routing protocols or a lower AD static is not present in the table.
Does the route ever get to be added to the route list? If I issue "show ip route", would I see it? Thanks.
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Dieg0M
Member Posts: 861
workfrom925 wrote: »
Does the route ever get to be added to the route list? If I issue "show ip route", would I see it? Thanks.
No it does not.Follow my CCDE journey at www.routingnull0.com -
Dieg0M
Member Posts: 861
networker050184 wrote: »Since the AD is high it will only be used in the even that a route from your routing protocols or a lower AD static is not present in the table.
I have to disagree with this. If the AD is 255 the router never adds the route to the routing table.
What Is Administrative Distance? - Cisco SystemsFollow my CCDE journey at www.routingnull0.com -
networker050184
Mod Posts: 11,962 Mod
Yes sorry Dieg0M is right. 255 does not get put into the routing table. Usually a distance of 250 is used for floating statics so they can be put into the routing table.An expert is a man who has made all the mistakes which can be made.
