Viewing Routes

To view the contents of all route tables:

tnsr# show route

To view the contents of a single route table:

tnsr# show route table <table name>

For example, to view the default IPv4 route table only, use:

tnsr# show route table ipv4-VRF:0

Route Flags

In the route display, the flags: row may contain the following:

no flags

If the flags line is empty, this is a normal route with no special actions.

local

This network is local to TNSR and packets to this destination will not leave the TNSR host.

drop

Packets matching this route will be dropped by TNSR. Commonly seen with null routes for subnets or for traffic which must not leave a subnet.

unreachable

Packets matching this route will be dropped by TNSR, and TNSR will send an ICMP “Destination unreachable” message back to the source address.

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.

Common Routes

Routing tables on TNSR may include unexpected entries by default or even after adding and configuring interfaces and other services. The following list covers several of these types of routes that may be present and what they mean:

0.0.0.0/32 (drop)

Null route to drop traffic with an empty address.

0.0.0.0/0

Default route for packets that do not match any other route, such as for Internet hosts or other remote destinations.

224.0.0.0/4 (drop)

Multicast that must not be routed.

224.0.0.0/24

Local subnet multicast.

240.0.0.0/4 (drop)

Reserved network that must not be routed.

255.255.255.255/32 (local)

Special broadcast address for networks local to TNSR.

x.x.x.<first>/32 (drop)

Null route for subnet configured on an interface. Last octet will vary depending on subnet size and network address. For example, this is .0 in a /24 subnet.

x.x.x.<last>/32 (drop)

Broadcast address for subnet configured on an interface. Last octet will vary depending on subnet size and network address. For example, this is .255 in a /24 subnet.

x.x.x.x/32 (local, next hop x.x.x.x/32)

Internal route for an address present on a TNSR interface.

Routes can also be added to the table dynamically by other processes such as via BGP or if an interface is configured as a DHCP client. Check the status or other associated logs for configured features to find the origins of these routes.