Re: ip route 0.0.0.0 V.S. ip default-network
Hi! This may not answer your questions completely but hope it helps at least somebody! Originating the default routes for different routing protocols (not all...). RIP and RIPv2 There are three possibilities: 1) If the RIP process has network 0.0.0.0 in its database, it will distribute this as-is. No additional commands are needed. 2) However, with default-information originate, you can put RIP to advertise a default route to all or certain interfaces, even if default does not exist. router rip (version 2) default-information originate route-map A route-map A permit 10 set interface serial 0 3) If nothing else is configured ip default-network command can be given. If the network specified in the command exist in the routing table then it is considered as a default route. IGRP and EIGRP There are three possibilities: 1) Use ip default-network . This command flags this route as default candidate and distributes it to neighbors. The same applies to IGRP and EIGRP. 2) Use ip default-network . This is much harder, since IOS automatically makes a summary route out of the classless network. Therefore, you need to have another ip default-network statement in order to get this working. Notice also, that the default network MUST BE present in IGRP/EIGRP routing process. It is not sufficient if it is just in the routers routing table! 3) If the default route (0.0.0.0/0) is already present in the routing table, then it can be redistributed BUT only into the EIGRP process and the process redistributes it to the neighbors. For IGRP, this cannot be done, so the only and the best way is to use the ip default-network -command. Notice also, that the flow of the default-information can be controlled by the default-information originate -command. OSPF There are three possibilities: 1) Create a default route with ip route 0.0.0.0 0.0.0.0 1.2.3.4 -command. Advertise this via OSPF with command default-information originate. Notice also, that if you have ip default-network -command in the router, then this is enough for OSPF to advertise default network. 2) Don´t create a static default. Advertise default with OSPF command default-information originate always. 3) Have default network in some other process. Redistribute this into OSPF process, which redistributes it to neighbors. Remember that is you have OSPF NSSA areas, then the default route must be advertised with area x nssa default-information originate-command. Aki ""shanjun zou"" <[EMAIL PROTECTED]> wrote in message 9319g7$fhd$[EMAIL PROTECTED]">news:9319g7$fhd$[EMAIL PROTECTED]... > Hi,every one > > when set the default route, is there any diffirence between ip route 0.0.0.0 > and ip default-network command? when will I use this one or another one ? > > thanks very much! > > ShanJun, zou > > > > _ > FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: ip route 0.0.0.0 V.S. ip default-network
check the link http://www.cisco.com/warp/public/105/default.html -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Aki Anttila Sent: Thursday, January 04, 2001 12:59 PM To: [EMAIL PROTECTED] Subject: Re: ip route 0.0.0.0 V.S. ip default-network Hi! This may not answer your questions completely but hope it helps at least somebody! Originating the default routes for different routing protocols (not all...). RIP and RIPv2 There are three possibilities: 1) If the RIP process has network 0.0.0.0 in its database, it will distribute this as-is. No additional commands are needed. 2) However, with default-information originate, you can put RIP to advertise a default route to all or certain interfaces, even if default does not exist. router rip (version 2) default-information originate route-map A route-map A permit 10 set interface serial 0 3) If nothing else is configured ip default-network command can be given. If the network specified in the command exist in the routing table then it is considered as a default route. IGRP and EIGRP There are three possibilities: 1) Use ip default-network . This command flags this route as default candidate and distributes it to neighbors. The same applies to IGRP and EIGRP. 2) Use ip default-network . This is much harder, since IOS automatically makes a summary route out of the classless network. Therefore, you need to have another ip default-network statement in order to get this working. Notice also, that the default network MUST BE present in IGRP/EIGRP routing process. It is not sufficient if it is just in the routers routing table! 3) If the default route (0.0.0.0/0) is already present in the routing table, then it can be redistributed BUT only into the EIGRP process and the process redistributes it to the neighbors. For IGRP, this cannot be done, so the only and the best way is to use the ip default-network -command. Notice also, that the flow of the default-information can be controlled by the default-information originate -command. OSPF There are three possibilities: 1) Create a default route with ip route 0.0.0.0 0.0.0.0 1.2.3.4 -command. Advertise this via OSPF with command default-information originate. Notice also, that if you have ip default-network -command in the router, then this is enough for OSPF to advertise default network. 2) Don´t create a static default. Advertise default with OSPF command default-information originate always. 3) Have default network in some other process. Redistribute this into OSPF process, which redistributes it to neighbors. Remember that is you have OSPF NSSA areas, then the default route must be advertised with area x nssa default-information originate-command. Aki ""shanjun zou"" <[EMAIL PROTECTED]> wrote in message 9319g7$fhd$[EMAIL PROTECTED]">news:9319g7$fhd$[EMAIL PROTECTED]... > Hi,every one > > when set the default route, is there any diffirence between ip route 0.0.0.0 > and ip default-network command? when will I use this one or another one ? > > thanks very much! > > ShanJun, zou > > > > _ > FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: ip route 0.0.0.0 V.S. ip default-network
Using the traditional, static means, your router receives a gateway of last resort that is fixed to a particular next hop router (or multiple in the event that you configure multiple) However, if the router has a number of outbound connections, you may not be maximizing your resiliency in this way. If you wanted a more dynamic GoLR selection means, you could install a default network (or multiple) that point to remote networks that the router generally has reachability to. In this case, they router will extract a GoLR next hop from the routing table which is generally dynamically created. Consider the following basic example. R1 ---path1---1.1.1.1/30> R2 10.0.0.0/8 ---path21.1.2.1/30> ^ In the example, R1 has two distinct paths to R2 beyond which the network 10.0.0.0/8 exists (ok, bad diagram i know :) One could configure an ip route 0.0.0.0 0.0.0.0 1.1.1.1 and in this way post a GoLR in the routing table statically. Or, one could post an ip default-network 10.0.0.0 in which case the router would choose one of 1.1.1.1 or 1.1.2.1 as the GoLR based on which of the two next hops were currently available. In this way, the router has protected itself and its GoLR selection process from a single point of failure. Hope that makes some sense. (I lost myself up near traditional :) Pete *** REPLY SEPARATOR *** On 1/4/2001 at 2:33 PM shanjun zou wrote: >Hi,every one > >when set the default route, is there any diffirence between ip route 0.0.0.0 >and ip default-network command? when will I use this one or another one ? > >thanks very much! > >ShanJun, zou > > > >_ >FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html >Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
