topic Re: Floating static route higher AD BGP in Routing and SD-WAN

Floating static route higher AD BGP

Bill19795_2 — Mon, 04 Mar 2019 19:25:34 GMT

I am setting up a remote site to provide a backup internet circuit for outbound traffic. Everything is working from the main site by redistributing a static route and using default-information originate within BGP to my MPLS provider.

Now on the remote site I setup a static route with an AD of 250 which is higher than the AD of 20 we are getting from the main site over the MPLS network. When the route come up BGP uses the default route from the main site and everything works fine. When I clear the BGP routes at the main site the backup site installs the static route with a higher AD. The problem is when the BGP route comes back up the static route is not getting removed. From looking at some other posts it seems that the redistributed local route is still preferred by BGP. They mentioned setting the weight to 0 in a route map which I tried but I am not getting the results of removing the static route and using the BGP route.

Remote site router config:

router bgp 65011

no synchronization

bgp log-neighbor-changes

network 12.100.1.4 mask 255.255.255.252

network 192.168.2.0

redistribute static route-map redist-static-bgp

neighbor 12.100.1.5 remote-as 1000

neighbor 12.100.1.5 send-community

neighbor 12.100.1.5 weight 40000

default-information originate

no auto-summary

ip forward-protocol nd

ip route 0.0.0.0 0.0.0.0 192.168.2.254 250

access-list 10 permit 0.0.0.0

access-list 10 deny any

route-map redist-static-bgp permit 10

match ip address 10

Everything working correctly:

Gateway of last resort is 12.100.1.5 to network 0.0.0.0

12.0.0.0/30 is subnetted, 3 subnets

B 12.100.1.0 [20/0] via 12.100.1.5, 00:00:48

C 12.100.1.4 is directly connected, Serial0/0

B 12.100.1.16 [20/0] via 12.100.1.5, 00:00:48

B 192.168.1.0/24 [20/0] via 12.100.1.5, 00:00:48

C 192.168.2.0/24 is directly connected, FastEthernet0/0

B 192.168.3.0/24 [20/0] via 12.100.1.5, 00:00:48

B* 0.0.0.0/0 [20/0] via 12.100.1.5, 00:00:48

RS1R1#show ip bgp

BGP table version is 9, local router ID is 192.168.2.253

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*> 0.0.0.0 12.100.1.5 40000 1000 65010 ?

*> 12.100.1.0/30 12.100.1.5 0 40000 1000 i

r> 12.100.1.4/30 12.100.1.5 0 40000 1000 i

r 0.0.0.0 0 32768 i

*> 12.100.1.16/30 12.100.1.5 0 40000 1000 i

*> 192.168.1.0 12.100.1.5 40000 1000 65010 i

*> 192.168.2.0 0.0.0.0 0 32768 i

*> 192.168.3.0 12.100.1.5 40000 1000 65012 i

RS1R1#

CLEAR IP BGP * :

RS1R1#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is 192.168.2.254 to network 0.0.0.0

12.0.0.0/30 is subnetted, 3 subnets

B 12.100.1.0 [20/0] via 12.100.1.5, 00:03:13

C 12.100.1.4 is directly connected, Serial0/0

B 12.100.1.16 [20/0] via 12.100.1.5, 00:03:13

B 192.168.1.0/24 [20/0] via 12.100.1.5, 00:00:12

C 192.168.2.0/24 is directly connected, FastEthernet0/0

B 192.168.3.0/24 [20/0] via 12.100.1.5, 00:03:13

S* 0.0.0.0/0 [250/0] via 192.168.2.254

RS1R1#show ip bgp

BGP table version is 13, local router ID is 192.168.2.253

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*> 0.0.0.0 192.168.2.254 0 32768 ?

*> 12.100.1.0/30 12.100.1.5 0 40000 1000 i

r> 12.100.1.4/30 12.100.1.5 0 40000 1000 i

r 0.0.0.0 0 32768 i

*> 12.100.1.16/30 12.100.1.5 0 40000 1000 i

*> 192.168.1.0 12.100.1.5 40000 1000 65010 i

*> 192.168.2.0 0.0.0.0 0 32768 i

*> 192.168.3.0 12.100.1.5 40000 1000 65012 i

RS1R1#

Re: Floating static route higher AD BGP

Peter Paluch — Mon, 14 Feb 2011 20:14:49 GMT

Bill,

I wonder - why do you actually redistribute the static default route into BGP on your remote site? Is that necessary for some other routers? What you see happening seems to be some kind of a race condition: because the default route from the main site goes away, the static backup route makes it into the routing table and subsequently to the BGP database. Now, even when the default route from the main site comes back, your router runs the BGP bestpath algorithm and it decides that the locally injected route is better than the route from the main site. This is kind of strange for me because the locally originated route is the third step in best path decision process (the first is the weight, the second is the local preference).

Nevertheless, my primary question is that whether it is appropriate to inject the default route into BGP on the remote site at all.

Best regards,

Peter

Re: Floating static route higher AD BGP

Bill19795_2 — Mon, 14 Feb 2011 22:39:10 GMT

I have several other sites that will use this backup site for Internet in the event the main site Internet is down. So in order to use default-information I will need a static route in the routing table.

Re: Floating static route higher AD BGP

Peter Paluch — Mon, 14 Feb 2011 22:58:57 GMT

Bill,

Allright then. I have had a closer look at the outputs you have provided. What surprises me is that after you do the clear ip bgp * on your remote site, there is only one default route present in your BGP table - the one that is locally redistributed into BGP. Specifically, there is no default route learned via BGP coming from the main site.

It looks to me as if the default route injected into BGP on the remote site gets advertised to the main site, and the main site considers it better than its own default route, so it uses it and does not advertise any default route back to the remote site. In other words, the main site does not assert itself but rather submits to the remote site as soon as the remote site starts advertising its default route. I guess we also need to inspect the processes running on the main site.

What you could do as a simple test: on the main site, set the local preference of the locally redistributed default route to, say, 200, and on the remote site, set the local preference of the locally redistributed default route to 150. This should force the routers to trust the main site more than the remote site. Don't forget to clear the BGP processes after making this modification.

Best regards,

Peter

Re: Floating static route higher AD BGP

milan.kulik — Tue, 15 Feb 2011 13:24:27 GMT

Hi Peter,

some corrections to your ideas:

1) The main site might be still advertising the default route. You don't receive it on the remote site because the BGP neighbor 12.100.1.5 is receiving the default route both from the backbone and from the remote site itself. And the prefix received from the remote site has better BGP attributes probably. So it's the 12.100.1.5 router which is not advertising the default received from the backbone (main site originally) to the remote site.

2) Local preference tuning will not help here. Local preference attribute is used only within the local AS, not advertised via eBGP. As the main and remote sites are within different ASes, it will not work.

3) IMHO, what's necessary here, is:

a) Setting the weight to 0 when redistributing the static default route to BGP on the remote site. (Locally originated prefixes are getting the weight 32768 by default. That's why the default route redistributed from static always beats the default route received from the backbone.)

b) Also setting local preference to 50 (or anything lower than the default 100) for the static default route redistributed to BGP.

This will make the default coming from the backbone to win.

c) Prepend the remote site AS number several times to the default route when advertising it to the eBGP neighbor.

When some third site (or even the 12.100.1.5 neighbor) receives the default route both from the main site and from the remote site, the longer AS_PATH created by prepending will make the default route originated from remote site less preferred.

HTH,

Milan

Re: Floating static route higher AD BGP

b-grace — Tue, 15 Feb 2011 14:14:46 GMT

So...you're trying to setup a primary and backup path out of your network. Is there any reason you can't build a BGP neighbor from the remotes up to the main (premise) routers. Then you can adjust the weight attribute on the neighbor statements to control preferred routes.

Re: Floating static route higher AD BGP

Peter Paluch — Tue, 15 Feb 2011 14:19:59 GMT

Hi Milan,

Thank you for replying!

1) The main site might be still advertising the default route. You don't
 receive it on the remote site because the BGP neighbor 12.100.1.5 is 
receiving the default route both from the backbone and from the remote 
site itself. And the prefix received from the remote site has better BGP
 attributes probably. So it's the 12.100.1.5 router which is not 
advertising the default received from the backbone (main site 
originally) to the remote site.

I guess that is exactly what I am saying, just probably I did not select the proper words for it. Perhaps a misunderstanding In any case, the remote site does not receive the default route from the main site, suggesting that the bestpath on main site still points towards the remote site, that's why it is not advertised back. We should definitely see the default route in the BGP database, advertised from the main site.

2) Local preference tuning will not help here. Local preference 
attribute is used only within the local AS, not advertised via eBGP. As 
the main and remote sites are within different ASes, it will not work.

Absolutely correct - I have overlooked that the two BGP speakers are in different autonomous systems. Thank you for pointing that out! Shame on me

I guess I am little at a loss in understanding the entire BGP setup in this case and the different locations interact with each other. Perhaps a brief exhibit showing the individual locations and the flow of routing information would be helpful.

Best regards,

Peter

Re: Floating static route higher AD BGP

milan.kulik — Tue, 15 Feb 2011 14:47:38 GMT

Hi Peter,

the topology used here is probably very similar to our enterprise network.

IMHO, it's important to understand the topology is quite complex:

As there is a provider MPLS backbone, there's probably a provider CE router on each site peering via eBGP with the customer router.

And also peering to provider PE router (backbone).

So on the main site, the customer router can still be using it's static default route as the best and advertise it to the provider.

On the remote site, the provider CE router (12.100.1.5 in our case) is receiving the default route via BGP from the remote PE router and also from the remote site customer router. And as the prefix received with shorter AS-PATH from the remote sites wins on the provider remote CE router.

I hope to be clearer now?

BR,

Milan

Re: Floating static route higher AD BGP

Bill19795_2 — Tue, 15 Feb 2011 16:32:11 GMT

Here is a diagram of the network. The goal is to provide backup outbound Internet only in the event the Internet at the HQ site is down.

Re: Floating static route higher AD BGP

milan.kulik — Tue, 15 Feb 2011 19:47:16 GMT

Hi,

so if the config you showed in the original post is still valid, you IMHO need to add to your RS1R1 config:

ip as-path access-list 1 permit ^$

route-map redist-static-bgp permit 10

match ip address 10

set weight 0

set local-preference 50

route-map prep-default out permit 10

match ip address 10

match as-path 1

set as-path prepend 65011 65011 65011 65011 65011

route-map prep-default out permit 20

router bgp 65011

neighbor 12.100.1.5 route-map prep-default out

After the config change, don't forget to apply

clear ip bgp * soft

HTH,

Milan

Re: Floating static route higher AD BGP

Bill19795_2 — Wed, 16 Feb 2011 14:10:08 GMT

Thanks for your help Milan.

This sort of works. Sometimes the static route will be removed at the remote site and sometimes it will not.

Remote site configuration:

router bgp 65011

no synchronization

bgp log-neighbor-changes

network 12.100.1.4 mask 255.255.255.252

network 192.168.2.0

redistribute static route-map redist-static-bgp

neighbor 12.100.1.5 remote-as 1000

neighbor 12.100.1.5 send-community

neighbor 12.100.1.5 weight 40000

neighbor 12.100.1.5 route-map prep-default out

default-information originate

no auto-summary

ip forward-protocol nd

ip route 0.0.0.0 0.0.0.0 192.168.2.254 250

ip as-path access-list 1 permit ^$

ip http server

no ip http secure-server

access-list 10 permit 0.0.0.0

access-list 10 deny any

access-list 20 permit 0.0.0.0

access-list 20 deny any

route-map redist-eigrp-bgp permit 10

match ip address 20

route-map prep-default permit 10

match ip address 10

match as-path 1

set as-path prepend 65011 65011 65011 65011 65011

route-map prep-default permit 20

route-map redist-static-bgp permit 10

match ip address 10

set local-preference 50

set weight 0

Remote site when everything is working as desired:

RS1R1#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is 12.100.1.5 to network 0.0.0.0

12.0.0.0/30 is subnetted, 3 subnets

B 12.100.1.0 [20/0] via 12.100.1.5, 00:03:43

C 12.100.1.4 is directly connected, Serial0/0

B 12.100.1.16 [20/0] via 12.100.1.5, 00:03:43

B 192.168.1.0/24 [20/0] via 12.100.1.5, 00:03:43

C 192.168.2.0/24 is directly connected, FastEthernet0/0

B 192.168.3.0/24 [20/0] via 12.100.1.5, 00:03:43

B* 0.0.0.0/0 [20/0] via 12.100.1.5, 00:03:43

RS1R1#show ip bgp

BGP table version is 9, local router ID is 192.168.2.253

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*> 0.0.0.0 12.100.1.5 40000 1000 65010 ?

*> 12.100.1.0/30 12.100.1.5 0 40000 1000 i

r> 12.100.1.4/30 12.100.1.5 0 40000 1000 i

r 0.0.0.0 0 32768 i

*> 12.100.1.16/30 12.100.1.5 0 40000 1000 i

*> 192.168.1.0 12.100.1.5 40000 1000 65010 i

*> 192.168.2.0 0.0.0.0 0 32768 i

*> 192.168.3.0 12.100.1.5 40000 1000 65012 i

RS1R1#

Shutdown HQ serial interface. Remote site routes:

RS1R1#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is 192.168.2.254 to network 0.0.0.0

12.0.0.0/30 is subnetted, 2 subnets

C 12.100.1.4 is directly connected, Serial0/0

B 12.100.1.16 [20/0] via 12.100.1.5, 00:07:05

C 192.168.2.0/24 is directly connected, FastEthernet0/0

B 192.168.3.0/24 [20/0] via 12.100.1.5, 00:07:05

S* 0.0.0.0/0 [250/0] via 192.168.2.254

RS1R1#show ip bgp

BGP table version is 13, local router ID is 192.168.2.253

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*> 0.0.0.0 192.168.2.254 0 50 0 ?

r> 12.100.1.4/30 12.100.1.5 0 40000 1000 i

r 0.0.0.0 0 32768 i

*> 12.100.1.16/30 12.100.1.5 0 40000 1000 i

*> 192.168.2.0 0.0.0.0 0 32768 i

*> 192.168.3.0 12.100.1.5 40000 1000 65012 i

RS1R1#

First time to bring HQ Serial back up. 192.168.1.x route is added. Remote site routes:

RS1R1#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is 12.100.1.5 to network 0.0.0.0

12.0.0.0/30 is subnetted, 3 subnets

B 12.100.1.0 [20/0] via 12.100.1.5, 00:01:00

C 12.100.1.4 is directly connected, Serial0/0

B 12.100.1.16 [20/0] via 12.100.1.5, 00:09:15

B 192.168.1.0/24 [20/0] via 12.100.1.5, 00:00:20

C 192.168.2.0/24 is directly connected, FastEthernet0/0

B 192.168.3.0/24 [20/0] via 12.100.1.5, 00:09:15

B* 0.0.0.0/0 [20/0] via 12.100.1.5, 00:00:20

RS1R1#

RS1R1#show ip bgp

BGP table version is 16, local router ID is 192.168.2.253

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*> 0.0.0.0 12.100.1.5 40000 1000 65010 ?

*> 12.100.1.0/30 12.100.1.5 0 40000 1000 i

r> 12.100.1.4/30 12.100.1.5 0 40000 1000 i

r 0.0.0.0 0 32768 i

*> 12.100.1.16/30 12.100.1.5 0 40000 1000 i

*> 192.168.1.0 12.100.1.5 40000 1000 65010 i

*> 192.168.2.0 0.0.0.0 0 32768 i

*> 192.168.3.0 12.100.1.5 40000 1000 65012 i

RS1R1#

Shutdown HQ site again. Routes get deleted:

RS1R1#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is 192.168.2.254 to network 0.0.0.0

12.0.0.0/30 is subnetted, 2 subnets

C 12.100.1.4 is directly connected, Serial0/0

B 12.100.1.16 [20/0] via 12.100.1.5, 00:10:57

C 192.168.2.0/24 is directly connected, FastEthernet0/0

B 192.168.3.0/24 [20/0] via 12.100.1.5, 00:10:57

S* 0.0.0.0/0 [250/0] via 192.168.2.254

RS1R1#show ip bgp

BGP table version is 20, local router ID is 192.168.2.253

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*> 0.0.0.0 192.168.2.254 0 50 0 ?

r> 12.100.1.4/30 12.100.1.5 0 40000 1000 i

r 0.0.0.0 0 32768 i

*> 12.100.1.16/30 12.100.1.5 0 40000 1000 i

*> 192.168.2.0 0.0.0.0 0 32768 i

*> 192.168.3.0 12.100.1.5 40000 1000 65012 i

RS1R1#

Bring HQ serial back up. Default route does not get removed:

RS1R1#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is 192.168.2.254 to network 0.0.0.0

12.0.0.0/30 is subnetted, 3 subnets

B 12.100.1.0 [20/0] via 12.100.1.5, 00:00:55

C 12.100.1.4 is directly connected, Serial0/0

B 12.100.1.16 [20/0] via 12.100.1.5, 00:12:42

B 192.168.1.0/24 [20/0] via 12.100.1.5, 00:00:17

C 192.168.2.0/24 is directly connected, FastEthernet0/0

B 192.168.3.0/24 [20/0] via 12.100.1.5, 00:12:42

S* 0.0.0.0/0 [250/0] via 192.168.2.254

RS1R1#show ip bgp

BGP table version is 22, local router ID is 192.168.2.253

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*> 0.0.0.0 192.168.2.254 0 50 0 ?

*> 12.100.1.0/30 12.100.1.5 0 40000 1000 i

r> 12.100.1.4/30 12.100.1.5 0 40000 1000 i

r 0.0.0.0 0 32768 i

*> 12.100.1.16/30 12.100.1.5 0 40000 1000 i

*> 192.168.1.0 12.100.1.5 40000 1000 65010 i

*> 192.168.2.0 0.0.0.0 0 32768 i

*> 192.168.3.0 12.100.1.5 40000 1000 65012 i

RS1R1#

Do you think this is some type of bug?

Re: Floating static route higher AD BGP

milan.kulik — Wed, 16 Feb 2011 14:37:44 GMT

Hi,

IMHO, it should be working. There might be route dampening of some other default route source bringing trouble, e.g.

It would be good to check at the moment it failed:

a) Is your main site still advertising the default route to the backbone?

b) Is the provider router 12.100.1.5 receiving the default route from the main site?

If yes, is it the best one?

BR,

Milan

Re: Floating static route higher AD BGP

Bill19795_2 — Wed, 16 Feb 2011 22:49:45 GMT

So it did start working after I verifed my configuration and restrted everything.

We are almost there. Now my problem is when I bounce the HQ connection everything works fine. When I use IP SLA at the HQ site it removes the route when the firewall is down and everything works as expected. I bring the firewall back up and the IP SLA puts the route back in but the BGP does not get updated. It's like the SLA does not trigger a routing update to the BGP peer.

Re: Floating static route higher AD BGP

Bill19795_2 — Wed, 16 Feb 2011 23:54:36 GMT

It seems as if the MPLS router never gets the update once the HQ router puts the default route back into it's routing table. The MPLS router never changes it's route from the RS1 router as it's gateway of last resort.

Re: Floating static route higher AD BGP

milan.kulik — Thu, 17 Feb 2011 07:33:24 GMT

Hi,

are you talking about your HQ MPLS router?

How does the IP SLA configuration look like on your HQ router in details?

BR,

Milan

Re: Floating static route higher AD BGP

Bill19795_2 — Thu, 17 Feb 2011 14:04:43 GMT

track 1 rtr 1 reachability

router bgp 65010

no synchronization

bgp log-neighbor-changes

network 12.100.1.0 mask 255.255.255.252

network 192.168.1.0

redistribute static route-map redist-static-bgp

redistribute eigrp 100 route-map redist-eigrp-bgp

neighbor 12.100.1.1 remote-as 1000

neighbor 12.100.1.1 weight 40000

default-information originate

no auto-summary

ip route 0.0.0.0 0.0.0.0 192.168.1.254 track 1

ip http server

no ip http secure-server

ip sla 1

icmp-echo 192.168.1.254 source-interface FastEthernet0/0

timeout 1000

frequency 3

ip sla schedule 1 life forever start-time now

access-list 10 permit 0.0.0.0

access-list 10 deny any

access-list 20 deny any

route-map redist-eigrp-bgp permit 10

match ip address 20

set metric 10

route-map redist-static-bgp permit 10

match ip address 10

HQR1#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is 192.168.1.254 to network 0.0.0.0

12.0.0.0/30 is subnetted, 2 subnets

C 12.100.1.0 is directly connected, Serial0/0

B 12.100.1.4 [20/0] via 12.100.1.1, 14:09:56

C 192.168.1.0/24 is directly connected, FastEthernet0/0

B 192.168.2.0/24 [20/0] via 12.100.1.1, 14:09:56

S* 0.0.0.0/0 [1/0] via 192.168.1.254

HQR1#

Shutdown interface with 192.168.1.254

HQR1#

HQR1#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is 12.100.1.1 to network 0.0.0.0

12.0.0.0/30 is subnetted, 2 subnets

C 12.100.1.0 is directly connected, Serial0/0

B 12.100.1.4 [20/0] via 12.100.1.1, 14:13:42

C 192.168.1.0/24 is directly connected, FastEthernet0/0

B 192.168.2.0/24 [20/0] via 12.100.1.1, 14:13:42

B* 0.0.0.0/0 [20/0] via 12.100.1.1, 00:00:01

HQR1#

Bring interface back up:

HQR1#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is 192.168.1.254 to network 0.0.0.0

12.0.0.0/30 is subnetted, 2 subnets

C 12.100.1.0 is directly connected, Serial0/0

B 12.100.1.4 [20/0] via 12.100.1.1, 14:14:08

C 192.168.1.0/24 is directly connected, FastEthernet0/0

B 192.168.2.0/24 [20/0] via 12.100.1.1, 14:14:08

S* 0.0.0.0/0 [1/0] via 192.168.1.254

Re: Floating static route higher AD BGP

milan.kulik — Thu, 17 Feb 2011 14:32:49 GMT

Hi,

how does

sh ip bgp

output on your HQ router look like after bringing the interface back up?

BR,

Milan

Re: Floating static route higher AD BGP

Bill19795_2 — Thu, 17 Feb 2011 16:32:58 GMT

Posting in a new thread so it does not change the formatting.

Re: Floating static route higher AD BGP

Bill19795_2 — Thu, 17 Feb 2011 16:35:27 GMT

HQ router with interface 192.168.1.254 up:

BGP table version is 35, local router ID is 192.168.1.253

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*> 0.0.0.0 192.168.1.254 0 32768 ?

r> 12.100.1.0/30 12.100.1.1 0 40000 1000 i

r 0.0.0.0 0 32768 i

*> 12.100.1.4/30 12.100.1.1 0 40000 1000 i

*> 192.168.1.0 0.0.0.0 0 32768 i

*> 192.168.2.0 12.100.1.1 40000 1000 65011 i

HQR1#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is 192.168.1.254 to network 0.0.0.0

12.0.0.0/30 is subnetted, 2 subnets

C 12.100.1.0 is directly connected, Serial0/0

B 12.100.1.4 [20/0] via 12.100.1.1, 00:01:41

C 192.168.1.0/24 is directly connected, FastEthernet0/0

B 192.168.2.0/24 [20/0] via 12.100.1.1, 00:01:41

S* 0.0.0.0/0 [1/0] via 192.168.1.254

HQR1#

MPLS1 router with HQ router sending default route:

MPLS1#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is 12.100.1.2 to network 0.0.0.0

12.0.0.0/30 is subnetted, 2 subnets

C 12.100.1.0 is directly connected, Serial0/0

C 12.100.1.4 is directly connected, Serial0/1

B 192.168.1.0/24 [20/0] via 12.100.1.2, 00:02:37

B 192.168.2.0/24 [20/0] via 12.100.1.6, 16:38:21

B* 0.0.0.0/0 [20/0] via 12.100.1.2, 00:02:37

MPLS1#show ip bgp

BGP table version is 13, local router ID is 12.100.1.17

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*> 0.0.0.0 12.100.1.2 0 0 65010 ?

*> 12.100.1.0/30 0.0.0.0 0 32768 i

*> 12.100.1.4/30 0.0.0.0 0 32768 i

*> 192.168.1.0 12.100.1.2 0 0 65010 i

*> 192.168.2.0 12.100.1.6 0 0 65011 i

MPLS1#show ip bgp 0.0.0.0

BGP routing table entry for 0.0.0.0/0, version 13

Paths: (1 available, best #1, table Default-IP-Routing-Table)

Flag: 0x820

Advertised to update-groups:

65010

12.100.1.2 from 12.100.1.2 (192.168.1.253)

Origin incomplete, metric 0, localpref 100, valid, external, best

MPLS1#

HQ Router when interface to 192.168.1.254 goes down:

HQR1#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is 12.100.1.1 to network 0.0.0.0

12.0.0.0/30 is subnetted, 2 subnets

C 12.100.1.0 is directly connected, Serial0/0

B 12.100.1.4 [20/0] via 12.100.1.1, 00:03:48

C 192.168.1.0/24 is directly connected, FastEthernet0/0

B 192.168.2.0/24 [20/0] via 12.100.1.1, 00:03:48

B* 0.0.0.0/0 [20/0] via 12.100.1.1, 00:00:02

HQR1#show ip bgp

BGP table version is 37, local router ID is 192.168.1.253

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*> 0.0.0.0 12.100.1.1 40000 1000 65011 65011 65011 65011 65011 65011 ?

r> 12.100.1.0/30 12.100.1.1 0 40000 1000 i

r 0.0.0.0 0 32768 i

*> 12.100.1.4/30 12.100.1.1 0 40000 1000 i

*> 192.168.1.0 0.0.0.0 0 32768 i

*> 192.168.2.0 12.100.1.1 40000 1000 65011 i

HQR1#

MPLS1 Router with interface down:

MPLS1#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is 12.100.1.6 to network 0.0.0.0

12.0.0.0/30 is subnetted, 2 subnets

C 12.100.1.0 is directly connected, Serial0/0

C 12.100.1.4 is directly connected, Serial0/1

B 192.168.1.0/24 [20/0] via 12.100.1.2, 00:04:57

B 192.168.2.0/24 [20/0] via 12.100.1.6, 16:40:40

B* 0.0.0.0/0 [20/0] via 12.100.1.6, 00:00:53

MPLS1#show ip bgp

BGP table version is 15, local router ID is 12.100.1.17

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*> 0.0.0.0 12.100.1.6 0 0 65011 65011 65011 65011 65011 65011 ?

*> 12.100.1.0/30 0.0.0.0 0 32768 i

*> 12.100.1.4/30 0.0.0.0 0 32768 i

*> 192.168.1.0 12.100.1.2 0 0 65010 i

*> 192.168.2.0 12.100.1.6 0 0 65011 i

MPLS1#show ip bgp 0.0.0.0

BGP routing table entry for 0.0.0.0/0, version 15

Paths: (1 available, best #1, table Default-IP-Routing-Table)

Flag: 0x820

Advertised to update-groups:

65011 65011 65011 65011 65011 65011

12.100.1.6 from 12.100.1.6 (192.168.2.253)

Origin incomplete, metric 0, localpref 100, valid, external, best

MPLS1#

HQ Router when interface is back up:

HQR1#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is 192.168.1.254 to network 0.0.0.0

12.0.0.0/30 is subnetted, 2 subnets

C 12.100.1.0 is directly connected, Serial0/0

B 12.100.1.4 [20/0] via 12.100.1.1, 00:07:18

C 192.168.1.0/24 is directly connected, FastEthernet0/0

B 192.168.2.0/24 [20/0] via 12.100.1.1, 00:07:18

S* 0.0.0.0/0 [1/0] via 192.168.1.254

HQR1#show ip bgp

BGP table version is 39, local router ID is 192.168.1.253

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

r 0.0.0.0 192.168.1.254 0 32768 ?

r> 12.100.1.1 40000 1000 65011 65011 65011 65011 65011 65011 ?

r> 12.100.1.0/30 12.100.1.1 0 40000 1000 i

r 0.0.0.0 0 32768 i

*> 12.100.1.4/30 12.100.1.1 0 40000 1000 i

*> 192.168.1.0 0.0.0.0 0 32768 i

*> 192.168.2.0 12.100.1.1 40000 1000 65011 i

HQR1#show ip bgp 0.0.0.0

BGP routing table entry for 0.0.0.0/0, version 39

Paths: (2 available, best #2, table Default-IP-Routing-Table, RIB-failure(17))

Not advertised to any peer

Local

192.168.1.254 from 0.0.0.0 (192.168.1.253)

Origin incomplete, metric 0, localpref 100, weight 32768, valid, sourced

1000 65011 65011 65011 65011 65011 65011

12.100.1.1 from 12.100.1.1 (12.100.1.17)

Origin incomplete, localpref 100, weight 40000, valid, external, best

HQR1#

MPLS router when interface is back up, still using RS1 default route:

MPLS1#

MPLS1#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is 12.100.1.6 to network 0.0.0.0

12.0.0.0/30 is subnetted, 2 subnets

C 12.100.1.0 is directly connected, Serial0/0

C 12.100.1.4 is directly connected, Serial0/1

B 192.168.1.0/24 [20/0] via 12.100.1.2, 00:08:37

B 192.168.2.0/24 [20/0] via 12.100.1.6, 16:44:21

B* 0.0.0.0/0 [20/0] via 12.100.1.6, 00:04:34

MPLS1#show ip bgp

BGP table version is 15, local router ID is 12.100.1.17

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*> 0.0.0.0 12.100.1.6 0 0 65011 65011 65011 65011 65011 65011 ?

*> 12.100.1.0/30 0.0.0.0 0 32768 i

*> 12.100.1.4/30 0.0.0.0 0 32768 i

*> 192.168.1.0 12.100.1.2 0 0 65010 i

*> 192.168.2.0 12.100.1.6 0 0 65011 i

MPLS1#show ip bgp 0.0.0.0

BGP routing table entry for 0.0.0.0/0, version 15

Paths: (1 available, best #1, table Default-IP-Routing-Table)

Flag: 0x820

Advertised to update-groups:

65011 65011 65011 65011 65011 65011

12.100.1.6 from 12.100.1.6 (192.168.2.253)

Origin incomplete, metric 0, localpref 100, valid, external, best

MPLS1#

Shut / no shut MPLS interface on HQ router:

HQR1#

*Mar 1 16:49:49.383: %SYS-5-CONFIG_I: Configured from console by consoleshow ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is 192.168.1.254 to network 0.0.0.0

12.0.0.0/30 is subnetted, 2 subnets

C 12.100.1.0 is directly connected, Serial0/0

B 12.100.1.4 [20/0] via 12.100.1.1, 00:00:46

C 192.168.1.0/24 is directly connected, FastEthernet0/0

B 192.168.2.0/24 [20/0] via 12.100.1.1, 00:00:46

S* 0.0.0.0/0 [1/0] via 192.168.1.254

HQR1#show ip bgp

BGP table version is 49, local router ID is 192.168.1.253

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*> 0.0.0.0 192.168.1.254 0 32768 ?

r> 12.100.1.0/30 12.100.1.1 0 40000 1000 i

r 0.0.0.0 0 32768 i

*> 12.100.1.4/30 12.100.1.1 0 40000 1000 i

*> 192.168.1.0 0.0.0.0 0 32768 i

*> 192.168.2.0 12.100.1.1 40000 1000 65011 i

HQR1#show ip bgp 0.0.0.0

BGP routing table entry for 0.0.0.0/0, version 40

Paths: (1 available, best #1, table Default-IP-Routing-Table)

Advertised to update-groups:

Local

192.168.1.254 from 0.0.0.0 (192.168.1.253)

Origin incomplete, metric 0, localpref 100, weight 32768, valid, sourced, best

HQR1#

MPLS Router after shut / no shut

MPLS1#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is 12.100.1.2 to network 0.0.0.0

12.0.0.0/30 is subnetted, 2 subnets

C 12.100.1.0 is directly connected, Serial0/0

C 12.100.1.4 is directly connected, Serial0/1

B 192.168.1.0/24 [20/0] via 12.100.1.2, 00:01:52

B 192.168.2.0/24 [20/0] via 12.100.1.6, 16:47:47

B* 0.0.0.0/0 [20/0] via 12.100.1.2, 00:01:52

MPLS1#show ip bgp

BGP table version is 18, local router ID is 12.100.1.17

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

*> 0.0.0.0 12.100.1.2 0 0 65010 ?

*> 12.100.1.0/30 0.0.0.0 0 32768 i

*> 12.100.1.4/30 0.0.0.0 0 32768 i

*> 192.168.1.0 12.100.1.2 0 0 65010 i

*> 192.168.2.0 12.100.1.6 0 0 65011 i

MPLS1#show ip bgp 0.0.0.0

BGP routing table entry for 0.0.0.0/0, version 18

Paths: (1 available, best #1, table Default-IP-Routing-Table)

Flag: 0x820

Advertised to update-groups:

65010

12.100.1.2 from 12.100.1.2 (192.168.1.253)

Origin incomplete, metric 0, localpref 100, valid, external, best

MPLS1#

Re: Floating static route higher AD BGP

milan.kulik — Thu, 17 Feb 2011 17:27:51 GMT

Hi,

I see you are using weight=40000 for prefixes received from the MPLS neighbor in your HQ.

Which means: When the interface 192.168.1.254 goes up again, the BGP process running on your HQ router inserts the static route to the BGP table with weight 32768..

But as there was also the default route received from the MPLS neighbor in the meantime with weight=40000, it remains the best!

You can see that from your output:

HQR1#show ip bgp

BGP table version is 39, local router ID is 192.168.1.253

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

r 0.0.0.0 192.168.1.254 0 32768 ?

r> 12.100.1.1 40000 1000 65011 65011 65011 65011 65011 65011 ?
...

Generally, playing with these preferences needs careful analysis: You need to think "what happens, when the prefix comes first from this direction and what about when it comes first from the other direction,...".

That explains what happens when you shutdown the interface connecting your HQ router to the MPLS neighbor:

The BGP table clears totally, the static routes gets inserted to the BGP database on your HQ router and when the BGP peering starts with the MPLS neighbor, the HQ router advertises the default route to the MPLS. As it has a shorter AS_PATH, it beats the default route received from the remote site and everything is OK again.

So IMHO, you need to decrease the weight assigned to the default route received from your MPLS neighbor in the HQ and everything should start working.

Just be careful not to break anything else - I don't see the reason why you are preferring the routes received from your neighbor here.

Notice there is an exactly opposite request here in the HQ comparing to what you want on the remote site: When a locally originated default route exists in HQ, it should beat the one received from your backbone!

HTH,

Milan