From: Alexei Monastyrnyi (alexeim@orcsoftware.com)
Date: Thu Sep 28 2006 - 18:49:06 ART
Hi Tony.
In fact R5 will receive updates from both R3 and R4. R4 being DR for
Ethernet segment doesn't make any difference here, it is a kind of "link
local" entity.
Below all router are in area 0 and Ethernet segment R3<->R4 is
172.16.32.0/22, R1 (read R5 for your layout) is connected via PPP links
to both R3 and R4
Trafic share i tis case is 1, but this is irrelevant IMHO for route
propagation.
So you have to filter from both R3 and R4 on R5, I suppose.
====
R4#sh ip ospf nei
Neighbor ID Pri State Dead Time Address Interface
3.3.3.3 1 FULL/BDR 00:00:33 172.16.34.3
Ethernet0/0
1.1.1.1 0 FULL/ - 00:01:54 172.16.124.2 Serial0/0
====
R3#sh ip ospf nei
Neighbor ID Pri State Dead Time Address Interface
1.1.1.1 0 FULL/ - 00:00:37 172.16.13.1 Serial0
4.4.4.4 1 FULL/DR 00:00:30 172.16.34.4 Ethernet1
====
R1#sh ip ospf nei
Neighbor ID Pri State Dead Time Address Interface
3.3.3.3 0 FULL/ - 00:00:34 172.16.13.3 Serial0
4.4.4.4 0 FULL/ - 00:01:50 172.16.124.4 Serial0.14
2.2.2.2 0 FULL/ - 00:01:38 172.16.124.5 Serial0.12
R1#sh ip route 172.16.32.0
Routing entry for 172.16.32.0/22
Known via "ospf 124", distance 110, metric 74, type intra area
Redistributing via eigrp 1
Advertised by eigrp 1 metric 10000 10 1 255 1500
Last update from 172.16.124.4 on Serial0.14, 00:08:41 ago
Routing Descriptor Blocks:
* 172.16.124.4, from 4.4.4.4, 00:08:41 ago, via Serial0.14
Route metric is 74, traffic share count is 1
172.16.13.3, from 4.4.4.4, 00:08:41 ago, via Serial0
Route metric is 74, traffic share count is 1
Tony Paterra wrote:
> Hey all, something I just noticed with broadcast networks in OSPF,
> curious if someone can confirm my rationale here...
>
> If I have 2 routers R3 and R4 in the same area (we'll call it area 2)
> connected to an ethernet segment and R4 is the DR... Now if we have
> R5 in the same area (but not on the ethernet segment), R5 will receive
> the route to the ethernet segment from the DR (R4) only. I'm looking
> at this for purposes of filtering...
>
>
> R3 <-Eth--> R4 (DR)
> \ /
> \ /
> R5
>
> So if I didn't want to use bandwidth or cost to influence the traffic,
> what Router ID would I filter when I configure it on R5? R4's
> loopback or R3's?
>
>
> Also, under the "show ip ospf database" command, what does Link ID
> stand for? From the docs it looks like a network number, but for the
> router LSA's it looks like a description of a router.
>
> Thanks!
This archive was generated by hypermail 2.1.4 : Sun Oct 01 2006 - 16:55:41 ART