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An OSPF question

 
 
aaabbb16@hotmail.com
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      09-12-2008
I config. ospf between two routers. (point to point).
I use "broadcast" parameter. It does not work, then
back to "point to point" it works.
I curious that how router know it connect to p2p or broadcast.
I don't think it based on full duplex.

TIA,
s
 
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Andre Wisniewski
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      09-13-2008
http://www.velocityreviews.com/forums/(E-Mail Removed) wrote:
> I config. ospf between two routers. (point to point).
> I use "broadcast" parameter. It does not work, then
> back to "point to point" it works.
> I curious that how router know it connect to p2p or broadcast.
> I don't think it based on full duplex.
>
> TIA,
> s


But router knows interface type, of course. serial interfaces are treated as p2p
, ethernet as broadcast, e.g.
 
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aaabbb16@hotmail.com
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Posts: n/a
 
      09-13-2008
On 9月13日, 上午3时44分, Andre Wisniewski <(E-Mail Removed)> wrote:
> (E-Mail Removed) wrote:
> > I config. ospf between two routers. (point to point).
> > I use "broadcast" parameter. It does not work, then
> > back to "point to point" it works.
> > I curious that how router know it connect to p2p or broadcast.
> > I don't think it based on full duplex.

>
> > TIA,
> > s

>
> But router knows interface type, of course. serial interfaces are treated as p2p
> , ethernet as broadcast, e.g.


Thanks, I use fast ethernet.
 
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Stephen
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      09-14-2008
On Sat, 13 Sep 2008 07:15:59 -0700 (PDT), (E-Mail Removed) wrote:

>On 9??13??, ????3??44??, Andre Wisniewski <(E-Mail Removed)> wrote:
>> (E-Mail Removed) wrote:
>> > I config. ospf between two routers. (point to point).
>> > I use "broadcast" parameter. It does not work, then
>> > back to "point to point" it works.
>> > I curious that how router know it connect to p2p or broadcast.
>> > I don't think it based on full duplex.

>>
>> > TIA,
>> > s

>>
>> But router knows interface type, of course. serial interfaces are treated as p2p
>> , ethernet as broadcast, e.g.

>
>Thanks, I use fast ethernet.


Broadcast should work over Ethernet - as long as both ends are
conifgured consistently. Make sure they are both in the same subnet,
same mask, same area.

you may want to turn on more detailed OSPF logging to see if there are
any diagnostics available via the internal log.
--
Regards

(E-Mail Removed) - replace xyz with ntl
 
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aaabbb16@hotmail.com
Guest
Posts: n/a
 
      09-14-2008
On 9月14日, 上午1时41分, Stephen <(E-Mail Removed)> wrote:
> On Sat, 13 Sep 2008 07:15:59 -0700 (PDT), (E-Mail Removed) wrote:
> >On 9??13??, ????3??44??, Andre Wisniewski <(E-Mail Removed)> wrote:
> >> (E-Mail Removed) wrote:
> >> > I config. ospf between two routers. (point to point).
> >> > I use "broadcast" parameter. It does not work, then
> >> > back to "point to point" it works.
> >> > I curious that how router know it connect to p2p or broadcast.
> >> > I don't think it based on full duplex.

>
> >> > TIA,
> >> > s

>
> >> But router knows interface type, of course. serial interfaces are treated as p2p
> >> , ethernet as broadcast, e.g.

>
> >Thanks, I use fast ethernet.

>
> Broadcast should work over Ethernet - as long as both ends are
> conifgured consistently. Make sure they are both in the same subnet,
> same mask, same area.
>
> you may want to turn on more detailed OSPF logging to see if there are
> any diagnostics available via the internal log.
> --
> Regards
>
> (E-Mail Removed) - replace xyz with ntl- 隐藏被引用文字 -
>
> - 显示引用的文字 -


Thanks,
I may not give a good descrption of my question.
Two routers (not cisco) direct connect via fast ethernet using ospf.
How do the routers know it is broadcast or p2p?
TIA,
/s

 
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Andre Wisniewski
Guest
Posts: n/a
 
      09-15-2008
(E-Mail Removed) wrote:
> On 9月14日, 上午1时41分, Stephen <(E-Mail Removed)> wrote:
>> On Sat, 13 Sep 2008 07:15:59 -0700 (PDT), (E-Mail Removed) wrote:
>>> On 9??13??, ????3??44??, Andre Wisniewski <(E-Mail Removed)> wrote:
>>>> (E-Mail Removed) wrote:
>>>>> I config. ospf between two routers. (point to point).
>>>>> I use "broadcast" parameter. It does not work, then
>>>>> back to "point to point" it works.
>>>>> I curious that how router know it connect to p2p or broadcast.
>>>>> I don't think it based on full duplex.
>>>>> TIA,
>>>>> s
>>>> But router knows interface type, of course. serial interfaces are treated as p2p
>>>> , ethernet as broadcast, e.g.
>>> Thanks, I use fast ethernet.

>> Broadcast should work over Ethernet - as long as both ends are
>> conifgured consistently. Make sure they are both in the same subnet,
>> same mask, same area.
>>
>> you may want to turn on more detailed OSPF logging to see if there are
>> any diagnostics available via the internal log.
>> --
>> Regards
>>
>> (E-Mail Removed) - replace xyz with ntl- 隐藏被引用文字 -
>>
>> - 显示引用的文字 -

>
> Thanks,
> I may not give a good descrption of my question.
> Two routers (not cisco) direct connect via fast ethernet using ospf.
> How do the routers know it is broadcast or p2p?
> TIA,
> /s
>


Once again, router knows which interface is installed.

If router detects an ethernet interface it knows that a broadcastable medium is
connected. Broadcast is essential for ethernet.

If router detects an serial interface it knows there is no broacastable medium.

If your questions refers to configuration statement "ip ospf network broadcast"
have a look at this great document
http://www.cisco.com/en/US/tech/tk36...80094e9e.shtml

Especially pay attention on sections Neighbors and Adjacencies. It's all
explained herein very well.

Andre

 
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aaabbb16@hotmail.com
Guest
Posts: n/a
 
      09-15-2008
On 9月15日, 上午10时49分, Andre Wisniewski <(E-Mail Removed)> wrote:
> (E-Mail Removed) wrote:
> > On 9月14日, 上午1时41分, Stephen <(E-Mail Removed)> wrote:
> >> On Sat, 13 Sep 2008 07:15:59 -0700 (PDT), (E-Mail Removed) wrote:
> >>> On 9??13??, ????3??44??, Andre Wisniewski <(E-Mail Removed)> wrote:
> >>>> (E-Mail Removed) wrote:
> >>>>> I config. ospf between two routers. (point to point).
> >>>>> I use "broadcast" parameter. It does not work, then
> >>>>> back to "point to point" it works.
> >>>>> I curious that how router know it connect to p2p or broadcast.
> >>>>> I don't think it based on full duplex.
> >>>>> TIA,
> >>>>> s
> >>>> But router knows interface type, of course. serial interfaces are treated as p2p
> >>>> , ethernet as broadcast, e.g.
> >>> Thanks, I use fast ethernet.
> >> Broadcast should work over Ethernet - as long as both ends are
> >> conifgured consistently. Make sure they are both in the same subnet,
> >> same mask, same area.

>
> >> you may want to turn on more detailed OSPF logging to see if there are
> >> any diagnostics available via the internal log.
> >> --
> >> Regards

>
> >> (E-Mail Removed) - replace xyz with ntl- 隐藏被引用文字 -

>
> >> - 显示引用的文字 -

>
> > Thanks,
> > I may not give a good descrption of my question.
> > Two routers (not cisco) direct connect via fast ethernet using ospf.
> > How do the routers know it is broadcast or p2p?
> > TIA,
> > /s

>
> Once again, router knows which interface is installed.
>
> If router detects an ethernet interface it knows that a broadcastable medium is
> connected. Broadcast is essential for ethernet.
>
> If router detects an serial interface it knows there is no broacastable medium.
>
> If your questions refers to configuration statement "ip ospf network broadcast"
> have a look at this great documenthttp://www.cisco.com/en/US/tech/tk365/technologies_white_paper09186a0...
>
> Especially pay attention on sections Neighbors and Adjacencies. It's all
> explained herein very well.
>
> Andre- 隐藏被引用文字 -
>
> - 显示引用的文字 -


Thanks, I have checked the cisco url you list above.
There is a command to assign network type "ip ospf network {broadcast
| non-
broadecast | point to multipoint}
My question is if two routers connected via ethernet, Do I should use
broadcast
or non-broadcast or either way?
/s
 
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Andre Wisniewski
Guest
Posts: n/a
 
      09-16-2008
(E-Mail Removed) wrote:
> On 9月15日, 上午10时49分, Andre Wisniewski <(E-Mail Removed)> wrote:
>> (E-Mail Removed) wrote:
>>> On 9月14日, 上午1时41分, Stephen <(E-Mail Removed)> wrote:
>>>> On Sat, 13 Sep 2008 07:15:59 -0700 (PDT), (E-Mail Removed) wrote:
>>>>> On 9??13??, ????3??44??, Andre Wisniewski <(E-Mail Removed)> wrote:
>>>>>> (E-Mail Removed) wrote:
>>>>>>> I config. ospf between two routers. (point to point).
>>>>>>> I use "broadcast" parameter. It does not work, then
>>>>>>> back to "point to point" it works.
>>>>>>> I curious that how router know it connect to p2p or broadcast.
>>>>>>> I don't think it based on full duplex.
>>>>>>> TIA,
>>>>>>> s
>>>>>> But router knows interface type, of course. serial interfaces are treated as p2p
>>>>>> , ethernet as broadcast, e.g.
>>>>> Thanks, I use fast ethernet.
>>>> Broadcast should work over Ethernet - as long as both ends are
>>>> conifgured consistently. Make sure they are both in the same subnet,
>>>> same mask, same area.
>>>> you may want to turn on more detailed OSPF logging to see if there are
>>>> any diagnostics available via the internal log.
>>>> --
>>>> Regards
>>>> (E-Mail Removed) - replace xyz with ntl- 隐藏被引用文字 -
>>>> - 显示引用的文字 -
>>> Thanks,
>>> I may not give a good descrption of my question.
>>> Two routers (not cisco) direct connect via fast ethernet using ospf.
>>> How do the routers know it is broadcast or p2p?
>>> TIA,
>>> /s

>> Once again, router knows which interface is installed.
>>
>> If router detects an ethernet interface it knows that a broadcastable medium is
>> connected. Broadcast is essential for ethernet.
>>
>> If router detects an serial interface it knows there is no broacastable medium.
>>
>> If your questions refers to configuration statement "ip ospf network broadcast"
>> have a look at this great documenthttp://www.cisco.com/en/US/tech/tk365/technologies_white_paper09186a0...
>>
>> Especially pay attention on sections Neighbors and Adjacencies. It's all
>> explained herein very well.
>>
>> Andre- 隐藏被引用文字 -
>>
>> - 显示引用的文字 -

>
> Thanks, I have checked the cisco url you list above.
> There is a command to assign network type "ip ospf network {broadcast
> | non-
> broadecast | point to multipoint}
> My question is if two routers connected via ethernet, Do I should use
> broadcast
> or non-broadcast or either way?
> /s


This command is used in interface configuration context and is used to change
default interface network type. You don't need it. There's no difference between
direct connected router or ones who are connected via a switch. Broadcast will
work either.

Andre
 
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Stephen
Guest
Posts: n/a
 
      09-16-2008
On Mon, 15 Sep 2008 13:08:03 -0700 (PDT), (E-Mail Removed) wrote:

>On 9??15??, ????10??49??, Andre Wisniewski <(E-Mail Removed)> wrote:
>> (E-Mail Removed) wrote:
>> > On 9??14??, ????1??41??, Stephen <(E-Mail Removed)> wrote:
>> >> On Sat, 13 Sep 2008 07:15:59 -0700 (PDT), (E-Mail Removed) wrote:
>> >>> On 9??13??, ????3??44??, Andre Wisniewski <(E-Mail Removed)> wrote:
>> >>>> (E-Mail Removed) wrote:
>> >>>>> I config. ospf between two routers. (point to point).
>> >>>>> I use "broadcast" parameter. It does not work, then
>> >>>>> back to "point to point" it works.
>> >>>>> I curious that how router know it connect to p2p or broadcast.
>> >>>>> I don't think it based on full duplex.
>> >>>>> TIA,
>> >>>>> s
>> >>>> But router knows interface type, of course. serial interfaces are treated as p2p
>> >>>> , ethernet as broadcast, e.g.
>> >>> Thanks, I use fast ethernet.
>> >> Broadcast should work over Ethernet - as long as both ends are
>> >> conifgured consistently. Make sure they are both in the same subnet,
>> >> same mask, same area.

>>
>> >> you may want to turn on more detailed OSPF logging to see if there are
>> >> any diagnostics available via the internal log.
>> >> --
>> >> Regards

>>
>> >> (E-Mail Removed) - replace xyz with ntl- ?????????????? -

>>
>> >> - ?????????????? -

>>
>> > Thanks,
>> > I may not give a good descrption of my question.
>> > Two routers (not cisco) direct connect via fast ethernet using ospf.
>> > How do the routers know it is broadcast or p2p?
>> > TIA,
>> > /s

>>
>> Once again, router knows which interface is installed.
>>
>> If router detects an ethernet interface it knows that a broadcastable medium is
>> connected. Broadcast is essential for ethernet.
>>
>> If router detects an serial interface it knows there is no broacastable medium.
>>
>> If your questions refers to configuration statement "ip ospf network broadcast"
>> have a look at this great documenthttp://www.cisco.com/en/US/tech/tk365/technologies_white_paper09186a0...
>>
>> Especially pay attention on sections Neighbors and Adjacencies. It's all
>> explained herein very well.
>>
>> Andre- ?????????????? -
>>
>> - ?????????????? -

>
>Thanks, I have checked the cisco url you list above.
>There is a command to assign network type "ip ospf network {broadcast
>| non-
>broadecast | point to multipoint}
>My question is if two routers connected via ethernet, Do I should use
>broadcast
>or non-broadcast or either way?
>/s


it depends.

some boxes (not cisco AFAIR) do not allow you to choose, as they limit
which options work on Ethernet.

I have had major hassles with cisco to foundry links on GigE which
will not work with some permutations of the choices - but do not
bother to log why they do not form an adjacency......

the "classic" argument is that point to point uses a bit less
resources in the router, so is "better" if you have a router with lots
of OSPF interface - but this needs more config.
Reality is if you are that close to the edge, your network is already
broken, but you havent provoked it enough yet......

However - you imply this is "just point to point" - with many OSPF
devices actually being switches and sometimes using adjacencies on
VLANs, you can end up with more than 2 devices in a subnet even when
all the pysical connections are point to point.
Here, making a special case for when there are only 2 devices may make
life more complicated.

personally - mimimum config and being consistent seems to cause fewer
problems so is the way to go. So - broadcast is my preferred setup.
--
Regards

(E-Mail Removed) - replace xyz with ntl
 
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Merv
Guest
Posts: n/a
 
      09-17-2008
On Sep 16, 4:13 pm, Stephen <(E-Mail Removed)> wrote:
> On Mon, 15 Sep 2008 13:08:03 -0700 (PDT), (E-Mail Removed) wrote:
> >On 9??15??, ????10??49??, Andre Wisniewski <(E-Mail Removed)> wrote:
> >> (E-Mail Removed) wrote:
> >> > On 9??14??, ????1??41??, Stephen <(E-Mail Removed)> wrote:
> >> >> On Sat, 13 Sep 2008 07:15:59 -0700 (PDT), (E-Mail Removed) wrote:
> >> >>> On 9??13??, ????3??44??, Andre Wisniewski <(E-Mail Removed)> wrote:
> >> >>>> (E-Mail Removed) wrote:
> >> >>>>> I config. ospf between two routers. (point to point).
> >> >>>>> I use "broadcast" parameter. It does not work, then
> >> >>>>> back to "point to point" it works.
> >> >>>>> I curious that how router know it connect to p2p or broadcast.
> >> >>>>> I don't think it based on full duplex.
> >> >>>>> TIA,
> >> >>>>> s
> >> >>>> But router knows interface type, of course. serial interfaces are treated as p2p
> >> >>>> , ethernet as broadcast, e.g.
> >> >>> Thanks, I use fast ethernet.
> >> >> Broadcast should work over Ethernet - as long as both ends are
> >> >> conifgured consistently. Make sure they are both in the same subnet,
> >> >> same mask, same area.

>
> >> >> you may want to turn on more detailed OSPF logging to see if there are
> >> >> any diagnostics available via the internal log.
> >> >> --
> >> >> Regards

>
> >> >> (E-Mail Removed) - replace xyz with ntl- ?????????????? -

>
> >> >> - ?????????????? -

>
> >> > Thanks,
> >> > I may not give a good descrption of my question.
> >> > Two routers (not cisco) direct connect via fast ethernet using ospf.
> >> > How do the routers know it is broadcast or p2p?
> >> > TIA,
> >> > /s

>
> >> Once again, router knows which interface is installed.

>
> >> If router detects an ethernet interface it knows that a broadcastable medium is
> >> connected. Broadcast is essential for ethernet.

>
> >> If router detects an serial interface it knows there is no broacastable medium.

>
> >> If your questions refers to configuration statement "ip ospf network broadcast"
> >> have a look at this great documenthttp://www.cisco.com/en/US/tech/tk365/technologies_white_paper09186a0...

>
> >> Especially pay attention on sections Neighbors and Adjacencies. It's all
> >> explained herein very well.

>
> >> Andre- ?????????????? -

>
> >> - ?????????????? -

>
> >Thanks, I have checked the cisco url you list above.
> >There is a command to assign network type "ip ospf network {broadcast
> >| non-
> >broadecast | point to multipoint}
> >My question is if two routers connected via ethernet, Do I should use
> >broadcast
> >or non-broadcast or either way?
> >/s

>
> it depends.
>
> some boxes (not cisco AFAIR) do not allow you to choose, as they limit
> which options work on Ethernet.
>
> I have had major hassles with cisco to foundry links on GigE which
> will not work with some permutations of the choices - but do not
> bother to log why they do not form an adjacency......
>
> the "classic" argument is that point to point uses a bit less
> resources in the router, so is "better" if you have a router with lots
> of OSPF interface - but this needs more config.
> Reality is if you are that close to the edge, your network is already
> broken, but you havent provoked it enough yet......
>
> However - you imply this is "just point to point" - with many OSPF
> devices actually being switches and sometimes using adjacencies on
> VLANs, you can end up with more than 2 devices in a subnet even when
> all the pysical connections are point to point.
> Here, making a special case for when there are only 2 devices may make
> life more complicated.
>
> personally - mimimum config and being consistent seems to cause fewer
> problems so is the way to go. So - broadcast is my preferred setup.
> --
> Regards
>
> (E-Mail Removed) - replace xyz with ntl



On a broadcast network, OSPF need to perform DR election.

This not required on a point-to-point link when OSPF network type is
configured as point-to-point and thus the OSPF adjacency should form
more quickly.

 
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