Routes are entered into TNSR using the
route (ipv4|ipv6) table <name>
command in configuration mode. When using the
route command for this
purpose, the address family and table name must be specified in order to
establish the routing context. This command enters
From there, individual routes can be managed.
config-route-table mode, the following commands are available:
Sets a description for the route table.
- route <destination-prefix>
Configures a route to the specified destination network. This enters
config-rttbl-next-hopmode where the remaining parameters for the route are set.
For a single address, use a
/32mask for IPv4 or
config-rttbl-next-hop mode, the following commands are available:
Sets a description for this route.
- next-hop <hop-id> via <action|gateway>
Configures how TNSR will handle traffic to this destination. This may be repeated multiple times with unique hop-id values to specify multiple destinations. The following parameters are available to control the route behavior:
The ID of the next hop. Must be unique between entries in the same route.
- via <ip-address>
Sets the next hop for this route as an IP address. Additional modifiers are possible for any
viaform using an IP address destination, see Route modifiers.
- via <ip-address> <interface>
Configures both the IP address and interface for the next hop. This is the most commonly used form for routes. May use modifiers, see Route modifiers.
- via <ip-address> next-hop-table <route-table-name>
Configures a recursive route lookup using a different route table. May use modifiers, see Route modifiers.
- via classify <classify-name>
Reserved for future use.
- via drop
Drops traffic to this destination (null route).
- via local
The destination is local to TNSR, such as an interface address or loopback.
- via null-send-prohibit
Packets matching this route will be dropped by TNSR, and TNSR will send an ICMP “Destination administratively prohibited” message back to the source address.
- via null-send-unreach
Packets matching this route will be dropped by TNSR, and TNSR will send an ICMP “Destination unreachable” message back to the source address.
For routes set with a next hop using
via <ip-address, additional modifiers
control how TNSR resolves the route destination.
Sets the administrative distance preference. Helps to choose between multiple possible destinations when routing protocols are used. This is only a local value, and a lower value is taken as being more reliable (closer).
The weight of routes to the same destination. Acts as a ratio of packets to deliver to each next hop.
Equal weights will deliver the same amount of traffic to all next hops for this destination prefix, uneven weights will deliver more traffic via the higher weighted connection. If one path has a weight of
1, and the other has a weight of
3, then the first path will receive 25% (
1/(1+3)) of the traffic and the other will receive 75% (
Sets a constraint on recursive route resolution via attached network. The next hop is unknown, but destinations in this prefix may be located via ARP.
Sets a constraint on recursive route resolution via host. The next hop is known, but the interface is not.
Multiple modifiers may be used together, but when doing so,
preference must be set first.
tnsr(config)# route ipv4 table ipv4-VRF:0 tnsr(config-route-table-v4)# route 10.2.10.0/24 tnsr(config-rttbl4-next-hop)# next-hop 0 via 10.2.0.2 GigabitEthernet0/14/2
tnsr(config)# route ipv6 table ipv6-VRF:0 tnsr(config-route-table-v6)# route fc07:b337:c4f3::/48 tnsr(config-rttbl6-next-hop)# next-hop 0 via 2001:db8:1::2 GigabitEthernet0/14/2
Breaking down the examples above, first the route table is specified. Within that context a destination network route is given. The destination network establishes a sub-context for a specific route. From there, the next hop configuration is entered.
When entering a next hop for a route in this way, both the IP address of the destination router and the interface must be given.
To specify more than one route, exit out of the
next-hop context so that
TNSR is in the correct context for the route table itself, then enter an
additional destination and next-hop.