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From: [email protected]
Sender: [email protected]
Date: Tue, 23 Nov 2010 20:49:27
To: <[email protected]>
Reply-to: [email protected]
Subject: CCIE_RS Digest, Vol 58, Issue 82
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Today's Topics:
1. Re: OSPF Election Time (David Betz)
2. Re: OSPF Election Time (Jason Maynard)
----------------------------------------------------------------------
Message: 1
Date: Tue, 23 Nov 2010 19:38:09 -0600
From: David Betz <[email protected]>
To: [email protected]
Subject: Re: [OSL | CCIE_RS] OSPF Election Time
Message-ID:
<[email protected]>
Content-Type: text/plain; charset="windows-1252"
I might need to clarify: What we are talking about is, once the devices
begin an election, how long do they wait before they say "OK, no new
candidates... let's vote"? The questions that you proposed are not part of
this scenario. They are, however, perfect examples of what would make R3
"too late" for the election process.
Let's also a assume a perfect understanding of the protocol from a Cisco
perspective as presented by Doyles book. I've not heard of him or Cisco.com
mentioning this. I would assume that it's some integral factor of the hello
time, but that's a complete guess.
On Tue, Nov 23, 2010 at 7:24 PM, Jason Maynard <[email protected]>wrote:
> Well that depends
>
>
>
> How long does the device take to boot up compared to other devices
>
> When is the device ready to participate in the OSPF election process
> (running more services on a device may take it longer to start participating
> compared to a router with less services)
>
>
>
> DR and BDR election is done via the Hello protocol ?
>
>
>
> OSPF Network Type | Hello | DR/BDR |
> _________________________________________
> Broadcast | 10sec | Elects DR/BDR|
> _________________________________________
> NonBroadcast | 30sec | Elects DR/BDR|
> _________________________________________
> P2MP | 30sec | No DR/BDR |
> _________________________________________
> P2MP NonBroadcast | 30sec | No DR/BDR |
> _________________________________________
> P2P | 10sec | No DR/BDR |
>
>
>
> If you want to control which devices become the DR/BDR you can use ?*ip
> ospf priority? and set all devices that you do not want to be DR/BDR to ?0?
> ***
>
>
>
> Not sure exactly how may hellos before the DR/BDR election takes place,
> perhaps I will lab it up to see -
>
>
>
> HTH
>
>
>
>
>
>
>
>
>
> *From:* [email protected] [mailto:
> [email protected]] *On Behalf Of *David Betz
> *Sent:* November-23-10 7:32 PM
> *To:* [email protected]
> *Subject:* [OSL | CCIE_RS] OSPF Election Time
>
>
>
> I've not been able to figure this out nor can I find any documentation for
> this: how long does OSPF wait for others to cast their vote before doing the
> DR/BDR election?
>
>
>
> If R1, R2, and R3 come online with 10.1.1.X/25 (X=RX) ip addresses, and R1
> and R2 see each other's messages, they will start an election. If R3 is
> there, it wins... if it's too late, R2 wins.
>
>
>
> When is "too late"?
>
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Message: 2
Date: Tue, 23 Nov 2010 20:49:25 -0500
From: "Jason Maynard" <[email protected]>
To: "'David Betz'" <[email protected]>, <[email protected]>
Subject: Re: [OSL | CCIE_RS] OSPF Election Time
Message-ID: <025701cb8b79$d3432dd0$79c989...@[email protected]>
Content-Type: text/plain; charset="us-ascii"
Have a look at the times below. Between two routers in a broadcast network
*Mar 1 00:09:00.215: OSPF: end of Wait on interface FastEthernet0/0
*Mar 1 00:09:00.215: OSPF: DR/BDR election on FastEthernet0/0
*Mar 1 00:09:00.219: OSPF: Elect BDR 222.222.222.222
*Mar 1 00:09:00.219: OSPF: Elect DR 222.222.222.222
*Mar 1 00:09:00.223: OSPF: Elect BDR 0.0.0.0
*Mar 1 00:09:00.223: OSPF: Elect DR 222.222.222.222
*Mar 1 00:09:00.227: DR: 222.222.222.222 (Id) BDR: none
*Mar 1 00:09:00.323: OSPF: 2 Way Communication to 1.1.1.1 on
FastEthernet0/0, state 2WAY
*Mar 1 00:09:00.323: OSPF: Neighbor change Event on interface
FastEthernet0/0
*Mar 1 00:09:00.327: OSPF: DR/BDR election on FastEthernet0/0
*Mar 1 00:09:00.327: OSPF: Elect BDR 1.1.1.1
*Mar 1 00:09:00.331: OSPF: Elect DR 222.222.222.222
*Mar 1 00:09:00.331: DR: 222.222.222.222 (Id) BDR: 1.1.1.1 (Id)
*Mar 1 00:09:00.331: OSPF: Send DBD to 1.1.1.1 on FastEthernet0/0 seq 0xA62
opt 0x52 flag 0x7 len 32
*Mar 1 00:09:00.331: OSPF: Neighbor change Event on interface
FastEthernet0/0
*Mar 1 00:09:00.331: OSPF: DR/BDR election on FastEthernet0/0
*Mar 1 00:09:00.331: OSPF: Elect BDR 1.1.1.1
*Mar 1 00:09:00.331: OSPF: Elect DR 222.222.222.222
*Mar 1 00:09:00.331: DR: 222.222.222.222 (Id) BDR: 1.1.1.1 (Id)
*Mar 1 00:09:00.331: OSPF: Neighbor change Event on interface
FastEthernet0/0
*Mar 1 00:09:00.331: OSPF: DR/BDR election on FastEthernet0/0
*Mar 1 00:09:00.331: OSPF: Elect BDR 1.1.1.1
*Mar 1 00:09:00.331: OSPF: Elect DR 222.222.222.222
*Mar 1 00:09:00.331: DR: 222.222.222.222 (Id) BDR: 1.1.1.1 (Id)
*Mar 1 00:09:00.331: OSPF: Rcv DBD from 1.1.1.1 on FastEthernet0/0 seq
0x1376 opt 0x52 flag 0x7 len 32 mtu 1500 state EXSTART
*Mar 1 00:09:00.331: OSPF: First DBD and we are not SLAVE
*Mar 1 00:09:00.379: OSPF: Rcv DBD from 1.1.1.1 on FastEthernet0/0 seq
0xA62 opt 0x52 flag 0x2 len 52 mtu 1500 state EXSTART
*Mar 1 00:09:00.383: OSPF: NBR Negotiation Done. We are the MASTER
*Mar 1 00:09:00.387: OSPF: Send DBD to 1.1.1.1 on FastEthernet0/0 seq 0xA63
opt 0x52 flag 0x3 len 52
*Mar 1 00:09:00.475: OSPF: Rcv DBD from 1.1.1.1 on FastEthernet0/0 seq
0xA63 opt 0x52 flag 0x0 len 32 mtu 1500 state EXCHANGE
*Mar 1 00:09:00.479: OSPF: Send DBD to 1.1.1.1 on FastEthernet0/0 seq 0xA64
opt 0x52 flag 0x1 len 32
*Mar 1 00:09:00.483: OSPF: Send LS REQ to 1.1.1.1 length 12 LSA count 1
*Mar 1 00:09:00.567: OSPF: Rcv LS REQ from 1.1.1.1 on FastEthernet0/0
length 36 LSA count 1
*Mar 1 00:09:00.571: OSPF: Send UPD to 10.0.0.2 on FastEthernet0/0 length
40 LSA count 1
*Mar 1 00:09:00.619: OSPF: Rcv DBD from 1.1.1.1 on FastEthernet0/0 seq
0xA64 opt 0x52 flag 0x0 len 32 mtu 1500 state EXCHANGE
*Mar 1 00:09:00.623: OSPF: Exchange Done with 1.1.1.1 on FastEthernet0/0
*Mar 1 00:09:00.623: OSPF: Rcv LS UPD from 1.1.1.1 on FastEthernet0/0
length 64 LSA count 1
*Mar 1 00:09:00.627: OSPF: Synchronized with 1.1.1.1 on FastEthernet0/0,
state FULL
*Mar 1 00:09:00.631: %OSPF-5-ADJCHG: Process 1, Nbr 1.1.1.1 on
FastEthernet0/0 from LOADING to FULL, Loading Done
*Mar 1 00:09:00.727: OSPF: Build network LSA for FastEthernet0/0, router ID
222.222.222.222
*Mar 1 00:09:00.731: OSPF: Build network LSA for FastEthernet0/0, router ID
222.222.222.222
*Mar 1 00:09:00.735: OSPF: Build router LSA for area 0, router ID
222.222.222.222, seq 0x80000004
*Mar 1 00:09:03.439: OSPF: Rcv LS UPD from 1.1.1.1 on FastEthernet0/0
length 64 LSA count 1
From: Jason Maynard [mailto:[email protected]]
Sent: November-23-10 8:25 PM
To: 'David Betz'; '[email protected]'
Subject: RE: [OSL | CCIE_RS] OSPF Election Time
Well that depends
How long does the device take to boot up compared to other devices
When is the device ready to participate in the OSPF election process
(running more services on a device may take it longer to start participating
compared to a router with less services)
DR and BDR election is done via the Hello protocol -
OSPF Network Type | Hello | DR/BDR |
_________________________________________
Broadcast | 10sec | Elects DR/BDR|
_________________________________________
NonBroadcast | 30sec | Elects DR/BDR|
_________________________________________
P2MP | 30sec | No DR/BDR |
_________________________________________
P2MP NonBroadcast | 30sec | No DR/BDR |
_________________________________________
P2P | 10sec | No DR/BDR |
If you want to control which devices become the DR/BDR you can use "ip ospf
priority" and set all devices that you do not want to be DR/BDR to "0"
Not sure exactly how may hellos before the DR/BDR election takes place,
perhaps I will lab it up to see -
HTH
From: [email protected]
[mailto:[email protected]] On Behalf Of David Betz
Sent: November-23-10 7:32 PM
To: [email protected]
Subject: [OSL | CCIE_RS] OSPF Election Time
I've not been able to figure this out nor can I find any documentation for
this: how long does OSPF wait for others to cast their vote before doing the
DR/BDR election?
If R1, R2, and R3 come online with 10.1.1.X/25 (X=RX) ip addresses, and R1
and R2 see each other's messages, they will start an election. If R3 is
there, it wins... if it's too late, R2 wins.
When is "too late"?
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