Re: OSPF Startup questions [7:33711]
Another resource for this would be RFC2178. Cebuano wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Thanks all for the different insights. Being in a teaching environment, these are just what i need to be able to explain the behavior/process in easier-to-digest terms. Elmer - Original Message - From: Priscilla Oppenheimer To: Sent: Wednesday, January 30, 2002 5:33 PM Subject: Re: OSPF Startup questions [7:33711] At 12:41 PM 1/30/02, Cebuano wrote: i would think that regardless if there's a new router with a higher RID that comes on line, the DR/BDR should be the default MASTER to initiate the exchange since he's got all the topology/links info in the area, except of course for scenarios where there is no DR/BDR. Both neighbors have information to send. The master/slave business is just a temporary relationship to allow the neighbors to exchange their information in a reliable fashion. There's no real reason for one router instead of the other to become the master. Remember that protocol design is modular. You should keep the database synchronization process separate from the DR/BDR election. The synchronization process is the first step in the adjacency-building process. Each router describes its database by sending a sequence of database description packets to its neighbor. Each database description packet has a sequence number. Database description packets sent by the master (polls) are acknowledged by the slave through echoing of the sequence number. Both polls and their responses contain summaries of link-state data. The master is the only one allowed to retransmit database description packets. The OSPF protocol developers could have chosen some other method to ensure reliability, such as opening a TCP session or inventing a client/server protocol with the DR acting as the server on networks that have a DR. Instead they invented a master/slave protocol. It's just how they decided to implement it. If you think about it, you can see that their method has some advantages. If you were in a computer science protocol development class, you could write an essay on why their method is best. As a CCIE candidate, however, I'm tempted to say, why ask why? ;-) Priscilla Elmer - Original Message - From: Rogell, Dennis To: 'Cebuano' Sent: Wednesday, January 30, 2002 12:19 PM Subject: RE: OSPF Startup questions [7:33711] You can make the Dr the higher rid , and the answer to 3 is it looks at sequence numbers not timestamps.If the information it receives is the same but the sequence number is greater that will be entered into ls database. hth Dennis Rogell CNE, CCNP nextiraone Formally Milgo Solutions Email : [EMAIL PROTECTED] Phone: (954) 846-5128 -Original Message- From: Cebuano [SMTP:[EMAIL PROTECTED]] Sent: Wednesday, January 30, 2002 08:38 To: [EMAIL PROTECTED] Subject: OSPF Startup questions [7:33711] Hi, group. I have a few questions to iron out regarding OSPF startup. 1. EXSTART - master/slave is created between each router and its adjacent DR/BDR. Q: But this election on who the master will be is mute because the router with the higher RID (thus) the DR/BDR acts as the master, right? If not, shouldn't the DR act as the master anyway since he ( or she) is the central distribution point for the area's topology? 2. LOADING - slave router sends an LS request if the master's DBD has a more up-to-date link-state entry. Q: up-to-date meaning timestamps?? But...what if there's no NTP server to synchronize them? Thanks. Elmer Priscilla Oppenheimer http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=33857t=33711 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
OSPF Startup questions [7:33711]
Hi, group. I have a few questions to iron out regarding OSPF startup. 1. EXSTART - master/slave is created between each router and its adjacent DR/BDR. Q: But this election on who the master will be is mute because the router with the higher RID (thus) the DR/BDR acts as the master, right? If not, shouldn't the DR act as the master anyway since he ( or she) is the central distribution point for the area's topology? 2. LOADING - slave router sends an LS request if the master's DBD has a more up-to-date link-state entry. Q: up-to-date meaning timestamps?? But...what if there's no NTP server to synchronize them? Thanks. Elmer Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=33711t=33711 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF Startup questions [7:33711]
Thanks, I should pay closer attention to Doyle next time. But still, i would think that regardless if there's a new router with a higher RID that comes on line, the DR/BDR should be the default MASTER to initiate the exchange since he's got all the topology/links info in the area, except of course for scenarios where there is no DR/BDR. Elmer - Original Message - From: Rogell, Dennis To: 'Cebuano' Sent: Wednesday, January 30, 2002 12:19 PM Subject: RE: OSPF Startup questions [7:33711] You can make the Dr the higher rid , and the answer to 3 is it looks at sequence numbers not timestamps.If the information it receives is the same but the sequence number is greater that will be entered into ls database. hth Dennis Rogell CNE, CCNP nextiraone Formally Milgo Solutions Email : [EMAIL PROTECTED] Phone: (954) 846-5128 -Original Message- From: Cebuano [SMTP:[EMAIL PROTECTED]] Sent: Wednesday, January 30, 2002 08:38 To: [EMAIL PROTECTED] Subject: OSPF Startup questions [7:33711] Hi, group. I have a few questions to iron out regarding OSPF startup. 1. EXSTART - master/slave is created between each router and its adjacent DR/BDR. Q: But this election on who the master will be is mute because the router with the higher RID (thus) the DR/BDR acts as the master, right? If not, shouldn't the DR act as the master anyway since he ( or she) is the central distribution point for the area's topology? 2. LOADING - slave router sends an LS request if the master's DBD has a more up-to-date link-state entry. Q: up-to-date meaning timestamps?? But...what if there's no NTP server to synchronize them? Thanks. Elmer Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=33724t=33711 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF Startup questions [7:33711]
At 12:41 PM 1/30/02, Cebuano wrote: i would think that regardless if there's a new router with a higher RID that comes on line, the DR/BDR should be the default MASTER to initiate the exchange since he's got all the topology/links info in the area, except of course for scenarios where there is no DR/BDR. Both neighbors have information to send. The master/slave business is just a temporary relationship to allow the neighbors to exchange their information in a reliable fashion. There's no real reason for one router instead of the other to become the master. Remember that protocol design is modular. You should keep the database synchronization process separate from the DR/BDR election. The synchronization process is the first step in the adjacency-building process. Each router describes its database by sending a sequence of database description packets to its neighbor. Each database description packet has a sequence number. Database description packets sent by the master (polls) are acknowledged by the slave through echoing of the sequence number. Both polls and their responses contain summaries of link-state data. The master is the only one allowed to retransmit database description packets. The OSPF protocol developers could have chosen some other method to ensure reliability, such as opening a TCP session or inventing a client/server protocol with the DR acting as the server on networks that have a DR. Instead they invented a master/slave protocol. It's just how they decided to implement it. If you think about it, you can see that their method has some advantages. If you were in a computer science protocol development class, you could write an essay on why their method is best. As a CCIE candidate, however, I'm tempted to say, why ask why? ;-) Priscilla Elmer - Original Message - From: Rogell, Dennis To: 'Cebuano' Sent: Wednesday, January 30, 2002 12:19 PM Subject: RE: OSPF Startup questions [7:33711] You can make the Dr the higher rid , and the answer to 3 is it looks at sequence numbers not timestamps.If the information it receives is the same but the sequence number is greater that will be entered into ls database. hth Dennis Rogell CNE, CCNP nextiraone Formally Milgo Solutions Email : [EMAIL PROTECTED] Phone: (954) 846-5128 -Original Message- From: Cebuano [SMTP:[EMAIL PROTECTED]] Sent: Wednesday, January 30, 2002 08:38 To: [EMAIL PROTECTED] Subject: OSPF Startup questions [7:33711] Hi, group. I have a few questions to iron out regarding OSPF startup. 1. EXSTART - master/slave is created between each router and its adjacent DR/BDR. Q: But this election on who the master will be is mute because the router with the higher RID (thus) the DR/BDR acts as the master, right? If not, shouldn't the DR act as the master anyway since he ( or she) is the central distribution point for the area's topology? 2. LOADING - slave router sends an LS request if the master's DBD has a more up-to-date link-state entry. Q: up-to-date meaning timestamps?? But...what if there's no NTP server to synchronize them? Thanks. Elmer Priscilla Oppenheimer http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=33775t=33711 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OSPF Startup questions [7:33711]
Thanks all for the different insights. Being in a teaching environment, these are just what i need to be able to explain the behavior/process in easier-to-digest terms. Elmer - Original Message - From: Priscilla Oppenheimer To: Sent: Wednesday, January 30, 2002 5:33 PM Subject: Re: OSPF Startup questions [7:33711] At 12:41 PM 1/30/02, Cebuano wrote: i would think that regardless if there's a new router with a higher RID that comes on line, the DR/BDR should be the default MASTER to initiate the exchange since he's got all the topology/links info in the area, except of course for scenarios where there is no DR/BDR. Both neighbors have information to send. The master/slave business is just a temporary relationship to allow the neighbors to exchange their information in a reliable fashion. There's no real reason for one router instead of the other to become the master. Remember that protocol design is modular. You should keep the database synchronization process separate from the DR/BDR election. The synchronization process is the first step in the adjacency-building process. Each router describes its database by sending a sequence of database description packets to its neighbor. Each database description packet has a sequence number. Database description packets sent by the master (polls) are acknowledged by the slave through echoing of the sequence number. Both polls and their responses contain summaries of link-state data. The master is the only one allowed to retransmit database description packets. The OSPF protocol developers could have chosen some other method to ensure reliability, such as opening a TCP session or inventing a client/server protocol with the DR acting as the server on networks that have a DR. Instead they invented a master/slave protocol. It's just how they decided to implement it. If you think about it, you can see that their method has some advantages. If you were in a computer science protocol development class, you could write an essay on why their method is best. As a CCIE candidate, however, I'm tempted to say, why ask why? ;-) Priscilla Elmer - Original Message - From: Rogell, Dennis To: 'Cebuano' Sent: Wednesday, January 30, 2002 12:19 PM Subject: RE: OSPF Startup questions [7:33711] You can make the Dr the higher rid , and the answer to 3 is it looks at sequence numbers not timestamps.If the information it receives is the same but the sequence number is greater that will be entered into ls database. hth Dennis Rogell CNE, CCNP nextiraone Formally Milgo Solutions Email : [EMAIL PROTECTED] Phone: (954) 846-5128 -Original Message- From: Cebuano [SMTP:[EMAIL PROTECTED]] Sent: Wednesday, January 30, 2002 08:38 To: [EMAIL PROTECTED] Subject: OSPF Startup questions [7:33711] Hi, group. I have a few questions to iron out regarding OSPF startup. 1. EXSTART - master/slave is created between each router and its adjacent DR/BDR. Q: But this election on who the master will be is mute because the router with the higher RID (thus) the DR/BDR acts as the master, right? If not, shouldn't the DR act as the master anyway since he ( or she) is the central distribution point for the area's topology? 2. LOADING - slave router sends an LS request if the master's DBD has a more up-to-date link-state entry. Q: up-to-date meaning timestamps?? But...what if there's no NTP server to synchronize them? Thanks. Elmer Priscilla Oppenheimer http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=33820t=33711 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
