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New Member

BGP routing issue

Hi,

I have 3 sites. 2 sites were IPVPN connections provided by service provider through their MPLS cloud and the 3rd one was P2P DLL lease Line.

I recieved new lines from the same ISP for the sites and this time all 3 will be connected to the ISP and there will be no P2P lease line connection.

I recieved DSL connection for SITE 1. and ethernet connection for the other sites site 2 and site 3 and BGP configuration for neighbour.

I configured site 2 with the new neighbour and it works.

i also applied the same setting to the site 3 which was DLL p2p CONNECTION with Site 2 but the traffic is still going throuhg SITE2 instead of going direct through the Service provided MPLS cloud. since earlier there was no BGP on this router, there were static routes and also site 2 is advertising route to SITE 3 via site 2. I tried removing advertisement on site 2 for site 3 but then i lost connectivity.

When i trace from site 3 to site 1 I go through the ISP directly but when i trace from SITE 1 to site 3 It still goes via site 2.

Please some one help me resolve this issue.

Thanks

5 REPLIES

Re: BGP routing issue

ok now you have to have the following

in site 1 :

router bgp x

neighbor x.x.x.x remote-as yy    - where x.x.x.x is the ISP bgp next hop

network y.y.y.y    mask xy.xy.xy.xy    -- the network supposed to be you site 1 LAN

site 2

router bgp x

neighbor x.x.x.x remote-as yy    - where x.x.x.x is the ISP bgp next hop

network y.y.y.y    mask xy.xy.xy.xy    -- the network supposed to be you site 2 LAN

Site 3

router bgp x

neighbor x.x.x.x remote-as yy    - where x.x.x.x is the ISP bgp next hop

network y.y.y.y    mask xy.xy.xy.xy    -- the network supposed to be you site 3 LAN

this is the standard and simple way, do you have your config like this

good luck

if helpful Rate

New Member

Re: BGP routing issue

Thanks for the input. I have succefully formed BGP neighbours by doing the configuration like specified but am facing an issue not related. what can be the cause of this problem.

the performance over the wan links are not good. I am getting tremendous delay and drops on this link. I tried to connect directly to the telco modem and ping the neighbour network and didnt find any problem. there were no drops or request timeout.

Please assist in troubleshooting this problem

regards

Salim

New Member

Re: BGP routing issue

Hi,

Has this network performance degredation issue always existed? If no, what has changed? Any "upgrades/downgrades" been performed, routing changes, etc???

Please check basics:

show ip bgp

show ip route

traceroute (using source of WAN interface) (then reconnect directly to SP Modem and do the same to confirm path)

show ip cef exact-route

show interface (check for input/CRC errors/output queue)

show policy-map interface (this is if you have QoS configured)

If your bgp output (show ip bgp ) is showing routing is going via a peer it shouldn't be, ask yourself why? BGP will choose the path with the best path attributes, so this unwanted path may be advertising prefixes with better metrics that your desired path! Or, the config on your router may be setting metrics (Local Pref, MED, AS-Path List) using route-maps, filter-lists, etc, so please check these and make sure they are correct!

What is your access type (FR, ATM, Ethernet, etc)? You may need to check if there is any shaping done on your router or provider router)?

Is there a Firewall between your router and the WAN modem?

Please check the above and return with feedback/outputs!

HTH

Regards,

Joe.

New Member

Re: BGP routing issue

Hi Salim,

Any updates on your issue?

Regards,

Joe.

Re: BGP routing issue

hi salim

check the patht he traffic use in both cases and compaire it to see if there are two diffrent routes/pathes or not

please, rate the helpful  post

good luck

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