OSPF problem

[netbeginner]

Hii,

I am configuring OSPF between two cisco L3 switches 4510 & 4507 (as of now between these switches static routes are confugured). Configured properly but it is not working..checked by removing the static routes.

router ospf 1

network 10.10.10.0 255.255.255.252 0.0.0.3 area 0

network 10.10.10.4 255.255.255.248 0.0.0.7 area 0

Where i am doing mistake pls. guide me.

Regards

[cisco.net]

Hello,

access-list 33 permit 10.10.10.8 0.0.0.3

access-list 33 permit 10.101.10.12 0.0.0.3

route-map selected_routes permit 10

match ip address 33

Why this above this are required in Switch B. especially ACL 33.

[Giuseppe Larosa]

Hello Sam,

that is a route filter that decides what static routes have to be published in the OSPF domain without the filter you would advertise in OSPF also other static routes that are present in IP routing table of SwitchB.

Hope to help

Giuseppe

[netbeginner]

Hii Giuseppe,

I was meaning about this ACL -->

access-list 33 permit 10.10.10.8 0.0.0.3

access-list 33 permit 10.101.10.12 0.0.0.3

Actually here in OSPF we are advertising route/network for 10.10.10.0 & 10.10.10.4 but in ACL provided by you it seems form 10.10.10.8 & 10.101.10.12

[Giuseppe Larosa]

Hello Sam,

I couldn't see the whole thread story so I had just provided an example the ACL has to be written to match your effective subnets

10.10.10.0/30

10.10.10.4/30

sorry for the confusion I've caused

Hope to help

Giuseppe

[netbeginner]

Hello Giuseppe/Friendzs,

Two more basic querries...

1) As of now default route is running between Switch A & Switch B i.e On switch B default route is advertised towards Switch A. After Configuring OSPF we'll remove the default route from Switch B. Hope it will work properly(ROute learn via new OSPF config) as like now with default route.

2) As mentioned on network diagram Switch A is running with BGP(with WAN/Provider network),after running OSPF on it(for Switch B and extended network). Hope there will not be any affect on BGP route learning process or something else. All will be proper as now.

Regards

[Giuseppe Larosa]

Hello Sam,

a) be aware that SwitchA can be using the default route to reach other networks not redistributed into OSPF so you need to consider also if making SwitchB to advertise an OSPF default route with

router ospf 1

default-information originate

b) the changes you are doing shouldn't influence the eBGP session unless SwitchA is sending a default route on provider based on the presence of a default route int its IP routing table.

BGP network commands for WAN Ip subnets work well regardless of the origin of the routes in the IP routing table so moving from static routes to OSPF routes don't cause problems.

Hope to help

Giuseppe

[netbeginner]

Hello Giuseppe,

Thanks but little confusion on Point A.

For Point A) you mean after removing default route from Switch B (Which is toward Switch A) i have to configure "default-information originate" under router ospf 1 on Switch B only (i.e not on Switch A) ..rest all OK.

Point B) is OK. As i understand that there would not be any problem on WAN BGP session with OSPF configuration.

[Giuseppe Larosa]

Hello Sam,

a) I didn't understand I thought it was the opposite in this case it is SwitchA that should use the default-originate command under router ospf process

Hope to help

Giuseppe

[netbeginner]

Hello Giuseppe,

Again i am confused... :-)

See...default route is configured on Switch "B" pointing towards Switch "A" IP.

Hence "default-originate" command should be on Switch "B". Please confirm once more command should be on Switch "A" or on Switch "B". ..Sorry.. for incovineience.

regards

[Giuseppe Larosa]

Hello Sam,

when you use static default routes you configure them on Ry pointing to Rx.

If you want to achieve a similar result when using a dynamic routing protocol like OSPF, the command has to be configured on the device that has to advertise the route to the other one so going back to my example it has to be configured on Rx.

In your case it is the same: it is SwitchB that has to receive a default route, so the default-information has to be configured on SwitchA.

Hope to help

Giuseppe

[netbeginner]

Hi Giuseppe

Thank Buddy for clearing this.

Pls suggest me for this last question.

I skipped to mention about one more static route (This route is for production devices connected/extended from Switch "B" as like router shown is diagram on previous post i.e for access port connectivity from switch B) which is configured on Switch A pointing towards Switch B IP .i.e "Ip route 10.10.1.32 255.255.255.224 10.10.1.5"

For this route also we need to advertise the route under OSPF on both the switches

ie.

Router OSPF 1

network 10.10.1.32 0.0.0.31 area 0

Please correct if i am wrong...

Regards

[Giuseppe Larosa]

Hello Sam,

you need to include the required subnets as network command on SwitchB only or in the ACL used in the redistribute static in SwitchB if it is a static route also.

Again when moving to dynamic routing protocol the router that had the static route is the one that has to receive the OSPF external route, and so the OSPF config has to be done on the other device.

as I explained you cannot use a network command for static routes (this can be done in BGP but not in OSPF)

you need simply to add a third line to the ACL with a permit for this required network.

Hope to help

Giuseppe

[netbeginner]

Hi Giuseppe,

This time "ip route 10.10.1.32 255.255.255.224 10.10.1.5" is configure on Switch "A".

and one(first IP) IP of this pool 10.10.1.33 is configured on Switch B (on one Vlan).

Still you think that no network command is required on Switch A or on Switch B under OSPF config. only ACL need to be configuered on Switch B for this pool... ?

regards

[Giuseppe Larosa]

Hello Sam,

>> d one(first IP) IP of this pool 10.10.1.33 is configured on Switch B

then

add a network.. area statement under router ospf on SwitchB

Hope to help

Giuseppe

[netbeginner]

Hii Giuseppe,

Fine Sir..

Will remove the static route for 10.10.1.32 netwrok from Switch "A" and will configure network command for the same under Router OSPF on Switch "B" only ....without any ACL for this subnet on any switch.

regards