UNIX System Administration Handbook - Evi Nemeth [212]
Both IGRP and EIGRP are distance-vector protocols, but they are designed to avoid the looping and convergence problems found in other DV systems. EIGRP in particular is widely regarded as the paragon of distance-vector routing. For most purposes, EIGRP and OSPF are equally functional.
In our opinion, it is best to stick with an established, nonproprietary, and multiply implemented routing protocol such as OSPF. More people are using and working on OSPF than EIGRP, and several implementations are available.
IS-IS: the ISO “standard”
IS-IS, the Intra-Domain Intermediate System to Intermediate System Routeing Protocol, is the International Organization for Standardization’s answer to OSPF. It was originally designed to manage “routeing” for the OSI network protocols and was later extended to handle IP routing.
Both IS-IS and OSPF were developed in the early 90s at a time when ISO protocols were politically in vogue. Early attention from the IETF helped to lend IS-IS a veneer of legitimacy for IP, but it seems to be falling farther and farther behind OSPF in popularity. Today, IS-IS use is rare. The protocol itself is mired with lots of ISO baggage and generally should be avoided.
MOSPF, DVMRP, and PIM: multicast routing protocols
MOSPF (Multicast OSPF), DVMRP (Distance Vector Multicast Routing Protocol), and PIM (Protocol Independent Multicast) are protocols designed to support IP multicasting, a technology that is not yet widely deployed. You can find pointers to more information about these protocols at www.mbone.com.
Router Discovery Protocol
Router Discovery Protocol uses ICMP messages sent to the IP multicast address 224.0.0.1 to announce and learn about other routers on a network. Unfortunately, not all routers currently make these announcements, and not all hosts listen to them. The hope is that someday this protocol will become more popular.
14.4 ROUTED: RIP YOURSELF A NEW HOLE
You may not be rich. You may not be good looking. But you’ll always have routed. routed was for a long time the standard UNIX routing daemon, and it’s still supplied with most every version of UNIX.5
routed speaks only RIP. Some routeds support RIP-2 and some don’t. If you need RIP-2 and your routed doesn’t support it, you can always use gated as a RIP-2 daemon instead. It’s just a bit more complicated, especially if you have to install it yourself. (You only really need RIP-2 if you have subnets with different mask lengths.)
routed can be run in server mode (-s) or in quiet mode (-q). Both modes listen for broadcasts, but only servers distribute their own information. Generally, only machines with multiple interfaces should be servers. If neither -s nor -q is specified, routed is supposed to run in quiet mode with one interface and in server mode with more. But on many systems, this feature is broken.6
See page 302 for more about route.
routed adds its discovered routes to the kernel’s routing table. Routes must be reheard at least every four minutes or they will be removed. However, routed knows which routes it has added and will not remove static routes that were installed with the route command.
routed -t can be used to debug routing. This option makes routed run in the foreground and print out all packets it sends or receives.
routed normally discovers routing information dynamically and does not require configuration. However, if your site contains gateways to the Internet or to other autonomous systems, you may have to take some additional steps to make these links work with routed.
If you have only a single outbound gateway, you can advertise it as a global default route by running its routed with the -g flag. This is analogous to setting the default route on a single machine, except that it is propagated