Routing table is not used in the process of forwarding. Based on the information in the routing table and other tables (FR maps, ARP tables, QoS policies, Label information Base, etc.) a new table called Forwarding Information Base (FIB) is built. Packets are forwarded (switched) based on the information in this table. This is ***extremely simplified*** version of Cisco Express Forwarding (CEF) foundation.
You can read more details about IOS internals, CEF and FIB in the following books: - Inside Cisco IOS Software Architecture: http://www.ciscopress.com/bookstore/product.asp?isbn=1578701813 - Cisco Express Forwarding: http://www.ciscopress.com/bookstore/product.asp?isbn=1587052369 -- Marko Milivojevic - CCIE #18427 Senior Technical Instructor - IPexpert FREE CCIE training: http://bit.ly/vLecture Mailto: [email protected] Telephone: +1.810.326.1444 Web: http://www.ipexpert.com/ On Sun, Nov 21, 2010 at 21:26, David Betz <[email protected]> wrote: > I've been looking, but I cannot seem to find what I'm looking for. Can > anyone direct me to any resources on the mechanics on the routing table? > My theory: all routing goes through the routing table and only the routing > table. It seems to me that in the running of a router, no packets ever > cares about what EIGRP, OSPF, BGP, or RIP are doing. They are > abstracted/black-boxed from the packet. If this is true, then, QED, EIGRP > does NOT provide load-balancing (as every books seems to suggest); it > provides multiple paths to the routing table and THE ROUTING TABLE provides > load balancing. This has been driving me mad for the longest time. I work > with extreme accuracies in my day job as an escalation engineer (core dump > analyzer) and I really need to have this perfectly precise in my mind or I'm > going to absolutely lose it. > In sum: isn't it all about the routing table... and the routing protocols > (IGP/EGP) just provide information to the routing table... with all routing > actually routing the routing table and ONLY the routing table? > If this is true, then when the routing table is solid... then, you have no > reason to look at the routing protocol databases or tables. > _______________________________________________ > For more information regarding industry leading CCIE Lab training, please > visit www.ipexpert.com > > _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com
