what is the difference between local route (L) and directly connected (C)?
I am reviewing the v2 release of ICND1 course materials. Looking at the student guide pg. 2-67 and 2-68, there is a screenshot of a routing table; some routes are marked with a C (directly connected) others with an L (local route). The explanation is unhelpful. C is defined as referring to directly connected networks, whereas L is defined as referring to "local routes and local interfaces within connected networks". So what's the difference, please? Thanks for any advice on this.
what is the difference between local route (L) and directly conn
Recent versions of the IOS software started displaying these local prefixes in the IPv4 routing table. As far as I know, this was always the case with IPv6 routing table and IPv6 addresses, and now it has been also adopted for the IPv4 routing table.
These entries do not basically tell you anything new as they merely state an obvious fact: your own IP address is reachable on a particular interface. Having this route in a routing table merely makes sure that the packet destined for your IP address will not be rerouted but rather processed locally. I believe that these entries were in the routing table even before they started being displayed, they just were hidden.
Re: what is the difference between local route (L) and directly
Thanks for the link. It appears there are several things going on with L routes. I summarize from the link you provided:
"1. when you configure "redistribute connected" under any routing process, the connected routes are redistributed, but the local routes are not.
2. The local entries are needed by the MTR feature. In MTR, one interface/IP address can belong to multiple topologies. If one topology is not enabled on one interface in MTR, that connected route is not present in that topology. However, the packets destined to that IP address must still be processed by the router that owns the IP address, even if that topology is not enabled on that interface. This is why local host routes are present in all topologies, even if the topology is disabled.
3. It is normal for local host routes to be listed in the IPv4 and IPv6 routing table for IP addresses of the router's interfaces. Their purpose is to create a corresponding CEF entry as a receive entry so that the packets destined to this IP address can be processed by the router itself. These routes cannot be redistributed into any routing protocol."
Redistributuion, MTR, and the differences between CEF-processing and the other two sorts of packet processing are way beyond what ICND1 students need to know however.
[toc:faq]The ProblemOn traditional switches whenever we have a trunk
interface we use the VLAN tag to demultiplex the VLANs. The switch needs
to determine which MAC Address table to look in for a forwarding
decision. To do this we require the switch to do...
[toc:faq]Introduction:Netdr is a tool available on a RSP720, Sup720 or
Sup32 that allows one to capture packets on the RP or SP inband. The
netdr command can be used to capture both Tx and Rx packets in the
software switching path. This is not a substitut...
IntroductionOSPF, being a link-state protocol, allows for every router
in the network to know of every link and OSPF speaker in the entire
network. From this picture each router independently runs the Shortest
Path First (SPF) algorithm to determine the b...