Re: OSPF: Flooding LSU/LSA [7:10803]
The standard procedure when receiving a valid LSA is to retransmit that LSA out a set of interfaces. However, section 13.3 of RFC 2328 describes a list of numerous caveats. One of those is that should you receive an LSA that in all probability was successfully received by other routers out a particular interface, there is no need to retransmit it. This applies particularly when you are not the DR or BDR and you receive an LSA from the DR. The standardized procedure is not to retransmit that LSA out the receiving interface. However, that LSA is retransmitted out of all other interfaces that do not conflict the with noted caveats in 13.3. As far as examples go, the DR sends to the rest of the broadcast segment as it is adjacent to all. Each of those routers in turn flood out whatever other transit interfaces they possess excluding the one where the LSA was received. Does that help? Pete *** REPLY SEPARATOR *** On 7/3/2001 at 9:42 AM Ole Drews Jensen wrote: I am currently reading the CiscoPress BSCN book, and I find myself a bit confused on the LSU/LSA procedures in OSPF. When many routers are connected on the same LAN segment, and are therefore neighbors to eachother, a DR and a BDR will be elected. First they write that routers do not flood OSPF updates/advertisements to all the OSPF routers (224.0.0.5), but only to the DR OSPF routers (224.0.0.6). It is then the task of the DR(s) to flood whatever needs to be flooded to all the routers. However, a little later in the book, they tell me that when a router receives an update from a DR router, it will flood it to all routers. They also write that when a router receives an update, it will flood it to all DR OSPF routers on other connected LAN segments. Can someone give me a simple explanation on who sends what to where? Thanks in advance, Ole ~~~ Ole Drews Jensen Systems Network Manager CCNA, MCSE, MCP+I RWR Enterprises, Inc. [EMAIL PROTECTED] ~~~ http://www.OleDrews.com/CCNP ~~~ NEED A JOB ??? http://www.oledrews.com/job ~~~ Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=10875t=10803 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: OSPF: Flooding LSU/LSA [7:10803]
So it kind of boils down to this: If we look at only one network, routers send lsu/lsa to only the DR/BDR, and the DR/BDR then send to all OSPF routers. Example 1: Router A = DROTHER Router B = DROTHER Router C = DR Router D = DROTHER Router E = BDR 1) Router A sends LSU/LSA to C E (224.0.0.6) 2) DR sends the LSU/LSA to A,B,C,D E (224.0.0.5) If Router B is connected to another OSPF network on one of its other interfaces, the following will happen: 3) Router B sends LSU/LSA to the DR/BDR routers of that network (224.0.0.6) 4) The DR of that network sends the LSU/LSA to all OSPF routers on that network (224.0.0.5) Am I right, or would this be to simplify it too much, or am I completely off the track??? Thanks, Ole ~~~ Ole Drews Jensen Systems Network Manager CCNA, MCSE, MCP+I RWR Enterprises, Inc. [EMAIL PROTECTED] ~~~ http://www.OleDrews.com/CCNP ~~~ NEED A JOB ??? http://www.oledrews.com/job ~~~ -Original Message- From: Peter Van Oene [mailto:[EMAIL PROTECTED]] Sent: Tuesday, July 03, 2001 1:57 PM To: Ole Drews Jensen; [EMAIL PROTECTED] Subject: Re: OSPF: Flooding LSU/LSA [7:10803] The standard procedure when receiving a valid LSA is to retransmit that LSA out a set of interfaces. However, section 13.3 of RFC 2328 describes a list of numerous caveats. One of those is that should you receive an LSA that in all probability was successfully received by other routers out a particular interface, there is no need to retransmit it. This applies particularly when you are not the DR or BDR and you receive an LSA from the DR. The standardized procedure is not to retransmit that LSA out the receiving interface. However, that LSA is retransmitted out of all other interfaces that do not conflict the with noted caveats in 13.3. As far as examples go, the DR sends to the rest of the broadcast segment as it is adjacent to all. Each of those routers in turn flood out whatever other transit interfaces they possess excluding the one where the LSA was received. Does that help? Pete *** REPLY SEPARATOR *** On 7/3/2001 at 9:42 AM Ole Drews Jensen wrote: I am currently reading the CiscoPress BSCN book, and I find myself a bit confused on the LSU/LSA procedures in OSPF. When many routers are connected on the same LAN segment, and are therefore neighbors to eachother, a DR and a BDR will be elected. First they write that routers do not flood OSPF updates/advertisements to all the OSPF routers (224.0.0.5), but only to the DR OSPF routers (224.0.0.6). It is then the task of the DR(s) to flood whatever needs to be flooded to all the routers. However, a little later in the book, they tell me that when a router receives an update from a DR router, it will flood it to all routers. They also write that when a router receives an update, it will flood it to all DR OSPF routers on other connected LAN segments. Can someone give me a simple explanation on who sends what to where? Thanks in advance, Ole ~~~ Ole Drews Jensen Systems Network Manager CCNA, MCSE, MCP+I RWR Enterprises, Inc. [EMAIL PROTECTED] ~~~ http://www.OleDrews.com/CCNP ~~~ NEED A JOB ??? http://www.oledrews.com/job ~~~ Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=10884t=10803 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: OSPF: Flooding LSU/LSA [7:10803]
This looks good. Keep in mind that the BDR does not transmit LSA's however, unless the DR fails to do so. *** REPLY SEPARATOR *** On 7/3/2001 at 2:08 PM Ole Drews Jensen wrote: So it kind of boils down to this: If we look at only one network, routers send lsu/lsa to only the DR/BDR, and the DR/BDR then send to all OSPF routers. Example 1: Router A = DROTHER Router B = DROTHER Router C = DR Router D = DROTHER Router E = BDR 1) Router A sends LSU/LSA to C E (224.0.0.6) 2) DR sends the LSU/LSA to A,B,C,D E (224.0.0.5) If Router B is connected to another OSPF network on one of its other interfaces, the following will happen: 3) Router B sends LSU/LSA to the DR/BDR routers of that network (224.0.0.6) 4) The DR of that network sends the LSU/LSA to all OSPF routers on that network (224.0.0.5) Am I right, or would this be to simplify it too much, or am I completely off the track??? Thanks, Ole ~~~ Ole Drews Jensen Systems Network Manager CCNA, MCSE, MCP+I RWR Enterprises, Inc. [EMAIL PROTECTED] ~~~ http://www.OleDrews.com/CCNP ~~~ NEED A JOB ??? http://www.oledrews.com/job ~~~ -Original Message- From: Peter Van Oene [mailto:[EMAIL PROTECTED]] Sent: Tuesday, July 03, 2001 1:57 PM To: Ole Drews Jensen; [EMAIL PROTECTED] Subject: Re: OSPF: Flooding LSU/LSA [7:10803] The standard procedure when receiving a valid LSA is to retransmit that LSA out a set of interfaces. However, section 13.3 of RFC 2328 describes a list of numerous caveats. One of those is that should you receive an LSA that in all probability was successfully received by other routers out a particular interface, there is no need to retransmit it. This applies particularly when you are not the DR or BDR and you receive an LSA from the DR. The standardized procedure is not to retransmit that LSA out the receiving interface. However, that LSA is retransmitted out of all other interfaces that do not conflict the with noted caveats in 13.3. As far as examples go, the DR sends to the rest of the broadcast segment as it is adjacent to all. Each of those routers in turn flood out whatever other transit interfaces they possess excluding the one where the LSA was received. Does that help? Pete *** REPLY SEPARATOR *** On 7/3/2001 at 9:42 AM Ole Drews Jensen wrote: I am currently reading the CiscoPress BSCN book, and I find myself a bit confused on the LSU/LSA procedures in OSPF. When many routers are connected on the same LAN segment, and are therefore neighbors to eachother, a DR and a BDR will be elected. First they write that routers do not flood OSPF updates/advertisements to all the OSPF routers (224.0.0.5), but only to the DR OSPF routers (224.0.0.6). It is then the task of the DR(s) to flood whatever needs to be flooded to all the routers. However, a little later in the book, they tell me that when a router receives an update from a DR router, it will flood it to all routers. They also write that when a router receives an update, it will flood it to all DR OSPF routers on other connected LAN segments. Can someone give me a simple explanation on who sends what to where? Thanks in advance, Ole ~~~ Ole Drews Jensen Systems Network Manager CCNA, MCSE, MCP+I RWR Enterprises, Inc. [EMAIL PROTECTED] ~~~ http://www.OleDrews.com/CCNP ~~~ NEED A JOB ??? http://www.oledrews.com/job ~~~ s Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=10885t=10803 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: OSPF: Flooding LSU/LSA [7:10803]
Thanks Peter, Ole ~~~ Ole Drews Jensen Systems Network Manager CCNA, MCSE, MCP+I RWR Enterprises, Inc. [EMAIL PROTECTED] ~~~ http://www.OleDrews.com/CCNP ~~~ NEED A JOB ??? http://www.oledrews.com/job ~~~ -Original Message- From: Peter Van Oene [mailto:[EMAIL PROTECTED]] Sent: Tuesday, July 03, 2001 2:37 PM To: [EMAIL PROTECTED] Subject: RE: OSPF: Flooding LSU/LSA [7:10803] This looks good. Keep in mind that the BDR does not transmit LSA's however, unless the DR fails to do so. *** REPLY SEPARATOR *** On 7/3/2001 at 2:08 PM Ole Drews Jensen wrote: So it kind of boils down to this: If we look at only one network, routers send lsu/lsa to only the DR/BDR, and the DR/BDR then send to all OSPF routers. Example 1: Router A = DROTHER Router B = DROTHER Router C = DR Router D = DROTHER Router E = BDR 1) Router A sends LSU/LSA to C E (224.0.0.6) 2) DR sends the LSU/LSA to A,B,C,D E (224.0.0.5) If Router B is connected to another OSPF network on one of its other interfaces, the following will happen: 3) Router B sends LSU/LSA to the DR/BDR routers of that network (224.0.0.6) 4) The DR of that network sends the LSU/LSA to all OSPF routers on that network (224.0.0.5) Am I right, or would this be to simplify it too much, or am I completely off the track??? Thanks, Ole ~~~ Ole Drews Jensen Systems Network Manager CCNA, MCSE, MCP+I RWR Enterprises, Inc. [EMAIL PROTECTED] ~~~ http://www.OleDrews.com/CCNP ~~~ NEED A JOB ??? http://www.oledrews.com/job ~~~ -Original Message- From: Peter Van Oene [mailto:[EMAIL PROTECTED]] Sent: Tuesday, July 03, 2001 1:57 PM To: Ole Drews Jensen; [EMAIL PROTECTED] Subject: Re: OSPF: Flooding LSU/LSA [7:10803] The standard procedure when receiving a valid LSA is to retransmit that LSA out a set of interfaces. However, section 13.3 of RFC 2328 describes a list of numerous caveats. One of those is that should you receive an LSA that in all probability was successfully received by other routers out a particular interface, there is no need to retransmit it. This applies particularly when you are not the DR or BDR and you receive an LSA from the DR. The standardized procedure is not to retransmit that LSA out the receiving interface. However, that LSA is retransmitted out of all other interfaces that do not conflict the with noted caveats in 13.3. As far as examples go, the DR sends to the rest of the broadcast segment as it is adjacent to all. Each of those routers in turn flood out whatever other transit interfaces they possess excluding the one where the LSA was received. Does that help? Pete *** REPLY SEPARATOR *** On 7/3/2001 at 9:42 AM Ole Drews Jensen wrote: I am currently reading the CiscoPress BSCN book, and I find myself a bit confused on the LSU/LSA procedures in OSPF. When many routers are connected on the same LAN segment, and are therefore neighbors to eachother, a DR and a BDR will be elected. First they write that routers do not flood OSPF updates/advertisements to all the OSPF routers (224.0.0.5), but only to the DR OSPF routers (224.0.0.6). It is then the task of the DR(s) to flood whatever needs to be flooded to all the routers. However, a little later in the book, they tell me that when a router receives an update from a DR router, it will flood it to all routers. They also write that when a router receives an update, it will flood it to all DR OSPF routers on other connected LAN segments. Can someone give me a simple explanation on who sends what to where? Thanks in advance, Ole ~~~ Ole Drews Jensen Systems Network Manager CCNA, MCSE, MCP+I RWR Enterprises, Inc. [EMAIL PROTECTED] ~~~ http://www.OleDrews.com/CCNP ~~~ NEED A JOB ??? http://www.oledrews.com/job ~~~ s Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=10890t=10803 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
