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Route Map

ccannon88567
Level 1
Level 1

Please can somebody explain what this route map is doing to the statics with tag 7?

Thank you in advance.

router ospf 1

router-id 172.103.11.113

log-adjacency-changes

redistribute static metric 1 subnets route-map OSPF_default

passive-interface default

no passive-interface Vlan2

no passive-interface FastEthernet1/0/1

no passive-interface FastEthernet2/0/1

network 172.25.0.0 0.0.255.255 area 0

network 172.27.0.0 0.0.255.255 area 0

network 172.30.0.0 0.0.255.255 area 0

network 172.103.11.0 0.0.0.127 area 0

network 172.103.18.0 0.0.0.255 area 0

!

ip classless

ip route 10.0.1.1 255.255.255.255 172.30.0.11 tag 7

ip route 10.0.1.10 255.255.255.255 172.30.0.11 tag 7

ip http server

!

!

access-list 5 permit X.X.X.0 0.0.0.255

access-list 5 permit X.239.34.0 0.0.0.255

access-list 5 permit X.239.35.0 0.0.0.255

access-list 5 permit X.102.6.0 0.0.0.255

access-list 5 permit X.102.7.0 0.0.0.255

access-list 5 permit X.102.8.0 0.0.0.255

access-list 5 permit X.102.9.0 0.0.0.255

access-list 5 permit X.30.0.0 0.0.255.255

access-list 6 deny any

access-list 7 deny any

access-list 8 permit any

access-list 144 permit ip X.X.X.0 0.0.0.255 172.103.0.0 0.0.255.255

access-list 144 permit ip X.X.X.0 0.0.0.255 172.103.0.0 0.0.255.255

route-map OSPF_default permit 7

match tag 7

!

2 Accepted Solutions

Accepted Solutions

'What does the permit 7 refer to if not the ACL?'

It is simply a list number used to order the lines in the route map. By default it is 10, 20, 30 and so on, but the person who had made the config ahs for some reason chosen the number 7 instead of the default 10.

HTH.

View solution in original post

Carlton

It is a coincidence that there is an access list 7 and that the route map is matching 7. The access list 7 has no effect on the redistribution of static routes into OSPF. Without seeing more of the config we do not know what that access list is for, but it is not redistribution.

If you notice when the static routes are configured they are given a tag value:

ip route 10.0.1.1 255.255.255.255 172.30.0.11 tag 7

ip route 10.0.1.10 255.255.255.255 172.30.0.11 tag 7

and it is that tag value that the route map is matching against. So the result here is that there are 2 static routes configured and both of them will be redistributed. Perhaps it would clarify the issue if we consider the possibility of another static route being configured on this router. If the other static route looked like this:

ip route 192.168.51.0 255.255.255.0 172.30.0.11

Then there would be 3 static routes but only 2 of them would be redistributed.

There may be circumstances where you have multiple static routes configured and for policy reasons you want only some (but not all) of them to be advertised by the dynamic routing protocol like OSPF. Assigning some of the static routes a particular value of tag allows a route map to control redistribution and to select the correct static routes to be redistributed.

HTH

Rick

HTH

Rick

View solution in original post

5 Replies 5

Giuseppe Larosa
Hall of Fame
Hall of Fame

Hello Carlton,

only static routes with route tag=7 are redistributed into the OSPF domain

>> redistribute static metric 1 subnets route-map OSPF_default

you can check this with

sh ip ospf database external 10.0.1.1

sh ip ospf database external 10.0.1.10

or if you see advertised by OSPF in

sh ip route 10.0.1.1

Hope to help

Giuseppe

Thanks Guislar.

I was confused as to whether ACL 7 (Deny any)had anything to do with this route map?

I thought the permit 7 refered to the ACL of deny any and the match tag 7 refered to the route - therefore stopping the redistrubution.

What does the permit 7 refer to if not the ACL?

'What does the permit 7 refer to if not the ACL?'

It is simply a list number used to order the lines in the route map. By default it is 10, 20, 30 and so on, but the person who had made the config ahs for some reason chosen the number 7 instead of the default 10.

HTH.

Carlton

It is a coincidence that there is an access list 7 and that the route map is matching 7. The access list 7 has no effect on the redistribution of static routes into OSPF. Without seeing more of the config we do not know what that access list is for, but it is not redistribution.

If you notice when the static routes are configured they are given a tag value:

ip route 10.0.1.1 255.255.255.255 172.30.0.11 tag 7

ip route 10.0.1.10 255.255.255.255 172.30.0.11 tag 7

and it is that tag value that the route map is matching against. So the result here is that there are 2 static routes configured and both of them will be redistributed. Perhaps it would clarify the issue if we consider the possibility of another static route being configured on this router. If the other static route looked like this:

ip route 192.168.51.0 255.255.255.0 172.30.0.11

Then there would be 3 static routes but only 2 of them would be redistributed.

There may be circumstances where you have multiple static routes configured and for policy reasons you want only some (but not all) of them to be advertised by the dynamic routing protocol like OSPF. Assigning some of the static routes a particular value of tag allows a route map to control redistribution and to select the correct static routes to be redistributed.

HTH

Rick

HTH

Rick

Thank you both for clearing that up.

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