Cisco routing table question

[Spev]

I am a bit confused on the difference between C & L on Cisco routing tables, for connected and local, and what their differences are. I am also confused on a routing table (although this is mostly legacy) using RIP how to tell what RIP protocol is being used? RIP, RIPv2, or RIPng? The only way I can see how to tell what RIP protocol is being used is if the routing table is in IPv6 because in that case it would have to be RIPng since it supports IPv6. But if the routing table was IPv4 how could you tell if the RIP route was RIP or RIPv2??

[Wombo]

I am a bit confused on the difference between C & L on Cisco routing tables, for connected and local, and what their differences are. I am also confused on a routing table (although this is mostly legacy) using RIP how to tell what RIP protocol is being used? RIP, RIPv2, or RIPng? The only way I can see how to tell what RIP protocol is being used is if the routing table is in IPv6 because in that case it would have to be RIPng since it supports IPv6. But if the routing table was IPv4 how could you tell if the RIP route was RIP or RIPv2??

The C lists the subnet where as the L is the actual interface address. It's annoying really, if you do show ip route just exclude L.

 

show ip route | exclude L (I prefer to see the subnets in my routing tables, so I exclude L)

 

As for RIP have you tried show ip protocols? To check if any ipv6 protocols are in use use show ipv6 protocols. You may also want to use show ip interface on the rip interface to view the IP statistics for that interface. You can also change the sent and receivable versions of rip under the interfaces with ip rip send/receive version 2 (you can have 1 and 2 at the same time by placing them both on one line separated by a space) ex: ip rip send version 1 2

 

Edit: Just checked on IOS 15.x, show ip protocols does shows the version for RIP and the interfaces it is running on. And thanks for the refresher, it's been a while since I've used RIP

[Spev]

The C lists the subnet where as the L is the actual interface address. It's annoying really, if you do show ip route just exclude L.

 

show ip route | exclude L (I prefer to see the subnets in my routing tables, so I exclude L)

 

As for RIP have you tried show ip protocols? To check if any ipv6 protocols are in use use show ipv6 protocols. You may also want to use show ip interface on the rip interface to view the IP statistics for that interface. You can also change the sent and receivable versions of rip under the interfaces with ip rip send/receive version 2 (you can have 1 and 2 at the same time by placing them both on one line separated by a space) ex: ip rip send version 1 2

 

Edit: Just checked on IOS 15.x, show ip protocols does shows the version for RIP and the interfaces it is running on. And thanks for the refresher, it's been a while since I've used RIP

Ok, do you know much about IPv6 tables?

 

C   2001:DB8:CAFE:3::/64 [0/0]

 

     via GigabitEthernet0/0, directly connected

 

L   2001:DB8:CAFE:3::1/128 [0/0]

 

     via GigabitEthernet0/0, receive

 

 

 

I'm confused on the difference between these 2. I notice on all ipv6 routing tables I have seen the Connected routes all have a Local route with the same address with an ::1/128. I'm trying to figure out the significance of this?

 

I guess this ties back to one of my original questions too, I'm not understanding Connected vs Local routes.

 

Edit: I guess it is the loopback address?

[Wombo]

Ok, do you know much about IPv6 tables?

 

C   2001:DB8:CAFE:3::/64 [0/0]

 

     via GigabitEthernet0/0, directly connected

 

L   2001:DB8:CAFE:3::1/128 [0/0]

 

     via GigabitEthernet0/0, receive

 

 

 

I'm confused on the difference between these 2. I notice on all ipv6 routing tables I have seen the Connected routes all have a Local route with the same address with an ::1/128. I'm trying to figure out the significance of this?

 

I guess this ties back to one of my original questions too, I'm not understanding Connected vs Local routes.

Basically the same thing as the IPv4. The 128 (32 in IPv4) indicates this is a single address, in this case it is the address assigned to the interface. The C is the actual subnet for the route. I believe Cisco does this in the newer IOS versions to reduce the number of recursive lookups that need to do be done and so there can be a specific CEF entry for the local subnet. For the most part you can ignore the L.

 

Try: show ipv6 route | exclude L

 

It should make things a lot easier to read. Just be aware that the line under the L will still be listed.

 

Also in the output of show ipv6 protocols you can see "IPv6 Routing Protocol is "connected"", this is where the C routes are coming from.

 

C - The whole subnet that is assigned to the interface

L - The individual address of the local interface