I am new to networking, and currently studying about how router learn different routes.
One of my lecture slides shows the following,
First of all, please have a look at this network,
I know that link local
is created in the routing table when interface is configured, and connected
is created when an interface is active.
Now, I tried the same scenario in Packet Tracer and here is what I got when i type show ip route
command,
Router#show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route
Gateway of last resort is not set
C 192.168.10.0/24 is directly connected, FastEthernet0/0
My question is,
- If the interface is active why there is still two entries (
C
andL
) in routing
table (in the photo), and just singleC
entry in my network ? - How come the diagram shows the ip address for link local
with subnet mask of32
because when I tried assigning ip address with/32
subnet mask to this interfacce, I got bad mask error ?
Best Answer
Assigning a /32 to an interface that connects to something else doesn't make any sense. You can assign the /32 to a loopback interface:
If you want to assign the
192.168.10.1
address to the GigabitEthernet0/0 interface which uses192.168.10.0/24
:This results in the network
192.168.10.0/24
entry in the routing table as a connected route (C
). I suppose it depends on the IOS version, but you can also get a local (not link local which is something else, entirely) route to the specific (/32
) address assigned to an interface in your router. My IOS does this. The version you have doesn't show theL
in the codes, whereas mine does as the first entry:`