How you can modify the route configuration is described below.
Basic attribute of a route
A route is determined unambiguously by the address pair (partner-address, own-address).
partner-address and own-address can be an IPv4, IPv6, INTF or NEA address. Hardly any NEA addresses are now to be found in configurations, however.
A route’s address pair is invariant. The only exception is when the partner-address is modified using a BCGEN commando in an emergency. The own-address, by contrast, cannot be modified.
Modifying route attributes
The following commands are available for modifying route attributes:
MODIFY-ROUTE-ATTRIBUTES
MODIFY-ROUTE (old command)
Modifying the manual switching of routes
The following commands are available for modifying routes and route paths:
MODIFY-ROUTE-PATH
MODIFY-ROUTE (old command)
Route paths can be modified only if the underlying route attribute is retained. This means in particular that the same own-address must also be used for the intermediate routes. All other route changes are inadmissible and cannot succeed.
The figures below show both admissible and inadmissible switchovers.
Examples of admissible switchovers
Route switchover from remote to remote
In the example a route is switched from remote to remote. This guarantees the invariance of the address pair.
The command is:
/MODIFY-ROUTE-PATH ROUTE-NAME=ES1,PATH=*VIA-ROUTER( -
/ ROUTER-ROUTE-NAME=RTR2)
Route switchover from node to remote
In the example a route is switched from node to remote. This also guarantees the invariance of the address pair.
The command is:
/MODIFY-ROUTE-PATH ROUTE-NAME=ES1,PATH=*VIA-ROUTER( -
/ ROUTER-ROUTE-NAME=RTR1)
Double route switchover: remote - node and remote - remote
In the example a remote route of router RTR3 is switched from remote to node and a second route from remote to remote. Here, too, the invariance of the address pair is ensured.
Two MODIFY commands are required:
/MODIFY-ROUTE-PATH ROUTE-NAME=ES2,PATH=*VIA-LINE( -/ LINE-NAME=LINE1)/MODIFY-ROUTE-PATH ROUTE-NAME=ES2,PATH=*VIA-ROUTER( -/ ROUTER-ROUTE-NAME=RTR3)
Examples of inadmissible switchovers
Three examples are provided below which cannot work because the invariance of the address pair and, in consequence, of the subpaths cannot be maintained.
Inadmissible route switchover with a change of the own-address
RTR2 has a different own-address from ES1; consequently the intermediate path is not appropriate and the switchover is not possible.
Inadmissible reassignment of the end system with a change of the own-address
The reassignment of end system ES1 behind the router does not work because the router is connected to a different own-address.
Inadmissible route switchover to another line
IPv4, IPv6 and INTF routes cannot be switched over to another line or another own address.