Last push for tonight, then I’m off to sleepy-land. Tomorrow, we’re getting a Nor’easter here in NH, meaning I have A Long Day coming.
policy routing – configuring the router to make a forwarding decision on some criteria other than the destination address.
process switching – the slow process whereby the router performs several steps to determine where and how to forward a packet.
CEF – Cisco Express Forwarding. CEF builds a forwarding information base created by looking at routes in the routing table. This FIB is used to make a forwarding decision – very speedy.
MLS – multilayer switching. Where a switch can make a forwarding decision on more than just the layer 2 information.
ARP – address resolution protocol. The protocol by which a device that knows a host IP can determine the data link/layer 2 information.
proxy ARP – a device that will send an ARP response on behalf of another device.
routed interface – in multilayer switches, a physical interface that has been defined to not be a switchport, but rather to behave like a router port would (i.e., no switching, VLAN or bridging information).
InARP – inverse ARP. In frame relay networks, this is how 2 routers attached to the cloud determine the IP of their adjacent neighbor, provided the DLCI.
fast switching – a caching mechanism based on destination IP address, not prefix, built when the first packet is process switched, subsequent packets are fast switched. Cached fast switch entries fall out of the table quickly.
TTL – time to live. When forwarded, a router will decrement a packet’s TTL by 1. A packet with a TTL of 0 cannot be forwarded any more.
classless routing – routing based on prefix, and then by default route if no matching prefix is found.
classful routing – routing based on classful address. If there are any subnets within the classful network, but no subnet matching the destination of the packet, the packet will die. Otherwise, default routed.
FIB – forwarding information base. This cache table is created by CEF based on the routing table.
adjacency table – used by CEF. Holds informatino about the next-hops that can be used to forward packets to.
control plane – in IP routing, a term referring to building IP routing tables by IP routing protocols.
switched interface – in multilayer switches, a port that is used as a layer 2 member of a VLAN.
data plane – in IP routing, this is talking about the process of forwarding packets.
IP routing – the process of determining how to forward a packet.
IP forwarding – the same as IP routing