BGP using route-maps within network command

[David Warren]

Hello,

I am hoping to get some advice regarding BGP and route-map configuration that we have on our MPLS router.  This config was implemented before my arrival and it has me somewhat confused.  We are advertising many networks out of our main office, even though the only networks that reside here are 10.10.x.x and 10.100.x.x.  The network commands have a route-map attached to them and I am not quite sure what this acheives.  Below are my config snippets.  I want to remove these excess network statements from BGP as I think they are creating routing loops within BGP. 

BGP Config

router bgp XXXXX

bgp log-neighbor-changes

network 10.10.0.0 mask 255.255.0.0

network 10.20.0.0 mask 255.255.0.0 route-map NoStatic

network 10.30.0.0 mask 255.255.0.0 route-map NoStatic

network 10.40.0.0 mask 255.255.0.0 route-map NoStatic

network 10.50.0.0 mask 255.255.0.0 route-map NoStatic

network 10.60.0.0 mask 255.255.0.0 route-map NoStatic

network 10.80.0.0 mask 255.255.0.0 route-map NoSt atic

network 10.90.0.0 mask 255.255.0.0 route-map NoStatic

network 10.100.0.0 mask 255.255.0.0

aggregate-address 10.100.0.0 255.255.0.0 summary-only

neighbor 10.254.100.2 remote-as 64663

neighbor 10.254.100.2 soft-reconfiguration inbound

neighbor 10.254.100.2 prefix-list harwood-out-tw out

Route-map Config

route-map NoStatic deny 10

match tag 30 40 50 60 80 90 100

!

route-map NoStatic permit 20

Tagging Config

ip route 10.20.0.0 255.255.0.0 10.250.20.2 250 tag 100 name BACKUP_ROUTE_GRE_HOUSTON

ip route 10.30.0.0 255.255.0.0 10.250.30.2 250 tag 30 name BACKUP_ROUTE_GRE_AUSTIN

ip route 10.40.0.0 255.255.0.0 10.250.40.2 250 tag 40 name BACKUP_ROUTE_GRE_FORTWORTH

ip route 10.50.0.0 255.255.0.0 10.250.50.2 250 tag 50 name BACKUP_ROUTE_GRE_WASHINGTON_DC

ip route 10.60.0.0 255.255.0.0 10.250.60.2 250 tag 60 name BACKUP_ROUTE_GRE_SANANTONIO

ip route 10.80.0.0 255.255.0.0 10.250.80.2 250 tag 80 name BACKUP_ROUTE_GRE_CHARLOTTE

ip route 10.90.0.0 255.255.0.0 10.250.90.2 250 tag 90 name BACKUP_ROUTE_GRE_WOODLANDS

[Lei Tian]

Hi David,

I guess the use for route-map is not advertise the routes if it is tagged with the number. But I am not sure if BGP looks tag. Do a show ip bgp 10.20.0.0, see if the router advertises the route in BGP table.

HTH,
Lei Tian

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[David Warren]

So this is the weird thing, and the reason I want to get rid of these network commands.  When everything is up and running normally, my router is only advertising two routes, 10.10.x.x and 10.100.x.x.  See Info below.  However, if one of my sites loses MPLS connectivity, lets say 10.50.x.x, then that route will then start advertising out of this site.  So the below output would then have 10.50.0.0/16.  Does that make sense? 

Router> show ip bgp nei 10.254.100.2 advertised-routes

BGP table version is 2376, local router ID is 10.250.90.10

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

              r RIB-failure, S Stale, m multipath, b backup-path, x best-external, f RT-Filter

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

   Network          Next Hop            Metric LocPrf Weight Path

*> 10.10.0.0/16     10.100.87.5         257024         32768 i

*> 10.100.0.0/16    10.100.87.5         257024         32768 i

[Lei Tian]

Hi David,

So I guess the static routes are floating routes with AD 250, and the router learns those routes from other routing protocol in normal siatuation. I am wondering why is the router not advertising those routes in that case. Can you post the output of show ip route 10.20.0.0 from the router, and the full config for BGP section?

HTH,

Lei Tian

[JohnTylerPearce · Accepted solution]

Sounds like redundancy has been built in somehow. Are there any macros, seem scrips, or ip SLA configured?


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[Simon Brooks]

Agreed john. Let us see full run config.


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[David Warren]

I think I have it figured out.  We have a backup VPN that connects a remote site (lets call it Site A) to the main office (Site B). The reason the remote site networks are advertised from the main office is so Site C can access Site A through Site B when the backup VPN is up.

Thanks for taking time to respond.