Poland
GRANDMETRIC Sp. z o.o.
ul. Metalowa 5, 60-118 Poznań, Poland
NIP 7792433527
+48 61 271 04 43
info@grandmetric.com
Sweden
Drottninggatan 86
111 36 Stockholm
+46 762 041 514
info@grandmetric.com
UK
Grandmetric LTD
Office 584b
182-184 High Street North
London
E6 2JA
+44 20 3321 5276
info@grandmetric.com
US Region
Grandmetric LLC
Lewes DE 19958
16192 Coastal Hwy USA
EIN: 98-1615498
+1 302 691 94 10
info@grandmetric.com
Technology: Routing
Area: Static routing
Vendor: Cisco
Title: Floating Static Routing
Software: 12.X , 15.X, IP Services
Platform: Catalyst 3560, 3750, 3850, 4500, 6500, ISR/ASR Routers
In situation when a router has two identical routes the decision regarding which one gets installed in the routing table is based on the lowest administrative distance. With static routing, we can deliberately use this behavior as a basic redundancy mechanism by configuring a backup route with
a higher administrative distance than the primary route.
To configure floating static routing you need to specify the backup route with higher administrative distance value in our case it is a number of 10:
R1#configure terminal
R1(config)#ip route 100.10.20.0 255.255.255.0 172.16.1.1
R1(config)#ip route 100.10.20.0 255.255.255.0 10.1.0.2 10
Verification commands:
We can verify current state of our floating static route by using below command. The best path has an administrative distance equal one, however the non-active backup path has value of 10.
R1#show ip static route 100.10.20.0/24
Codes: M - Manual static, A - AAA download, N - IP NAT, D - DHCP,
G - GPRS, V - Crypto VPN, C - CASA, P - Channel interface processor,
B - BootP, S - Service selection gateway
DN - Default Network, T - Tracking object
L - TL1, E - OER, I - iEdge
D1 - Dot1x Vlan Network, K - MWAM Route
PP - PPP default route, MR - MRIPv6, SS - SSLVPN
H - IPe Host, ID - IPe Domain Broadcast
U - User GPRS, TE - MPLS Traffic-eng, LI - LIIN
Codes in []: A - active, N - non-active, B - BFD-tracked, D - Not Tracked, P - permanent
M 100.10.20.0/24 [1/0] via 172.16.1.1 [A]
M [10/0] via 10.1.0.2 [N]
Once in any reason the primary path goes done we can verify the network state with the same command and check if backup takes priority.
R1#sh ip static route 100.10.20.0/24
Codes: M - Manual static, A - AAA download, N - IP NAT, D - DHCP,
G - GPRS, V - Crypto VPN, C - CASA, P - Channel interface processor,
B - BootP, S - Service selection gateway
DN - Default Network, T - Tracking object
L - TL1, E - OER, I - iEdge
D1 - Dot1x Vlan Network, K - MWAM Route
PP - PPP default route, MR - MRIPv6, SS - SSLVPN
H - IPe Host, ID - IPe Domain Broadcast
U - User GPRS, TE - MPLS Traffic-eng, LI - LIIN
Codes in []: A - active, N - non-active, B - BFD-tracked, D - Not Tracked, P - permanent
M 100.10.20.0/24 [1/0] via 172.16.1.1 [N]
M [10/0] via 10.1.0.2 [A]