Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

Replacing Point-Point T1 with MPLS Managed Circuit

RouterA and RouterB are both running ospf as their IGP. My company has decided to replace the point to point t1 with a managed mpls circuit.

According to the new provider it should transparent and will just be an ”Ethernet handoff. " Question: what do I configure on RouterA to connect through the mpls cloud over to RouterB? Do I configure ebgp and perform bi-directional redistribution? Do I create a GRE tunnel from RouterA to RouterB?

Sorry, connectivity through a managed mpls provider cloud is new to me. Thanks in advance.

2 ACCEPTED SOLUTIONS

Accepted Solutions

Re: Replacing Point-Point T1 with MPLS Managed Circuit

Hi,

Yes.. we need to redistribute BGP routes into IGP so that Lcation B Networks will be reachable via BGP and vice versa.

The best way to advertise the network into MPLS cloud is use network command instead of redistributing into BGP.

Redistribute BGP routes into OSPF, But advertise the OSPF routes into BGP via "Network" Command.

Example : Advertise Location A network into BGP via network command at the same device redistribute BGP routes into OSPF, The same thing vice vera in Location B side.

As per BGP rule, the network which we are advertising into BGP, that should be reachable via IGP then only that route will be installed into BGP routing table else it will be in BGP table not into BGP Routing Table.

so the traffic flow from Location A to Location B is like this

User Location A  ---(IGP)--- > CE(A side)--- Look up Destination in BGP Routing Table ---> MPLS CLoud --- > CE(B Side) --- (IGP) --- > User Location B.

Regards

Karuppu

Hall of Fame Super Gold

Re: Replacing Point-Point T1 with MPLS Managed Circuit

Ethernet handoff should mean you will have L2 connectivity.

Even if it is not that (L3 MPLS), it is not said you will have to configure BGP or other routing protocols to them.

Ask your SP for a detailed axplaination of the service given.

5 REPLIES

Re: Replacing Point-Point T1 with MPLS Managed Circuit

Hi,


Better to have MPLS instead of P2P Link

Since you are going to buy MPLS link, they will provide one /30 IP address for your one side location(Router A - CE IP address) and the same another /30 IP address they will provide for your another Location and they will let you know their /30 IP address as well (PE IP address)

CE - Customer Edge that is your IP address , PE - Provider Edge that is Service Provider IP address

Now you have to replace with your OSPF  into BGP.

Router A  --(eBGP)-- > Service Provider (A Side) ----(MPLS Cloud)----> Service Provider(B Side) ---(eBGP)---> Router B

You need to configure eBGP between your Router A(CE) to Service Provider(A) and Router B(CE) to Service Provider(B) then advertise your network into the MPLS cloud via your BGP .

Sample Config:

router bgp 12345(your private AS number)
no synchronization
bgp log-neighbor-changes
network 10.10.0.0 mask 255.255.0.0  // advertising your network into MPLS cloud//
network 10.46.202.0 mask 255.255.255.0
neighbor remote-as
no auto-summary

regards

Karuppu

New Member

Re: Replacing Point-Point T1 with MPLS Managed Circuit

Dont he need mutual redistribution

Re: Replacing Point-Point T1 with MPLS Managed Circuit

Hi,

Yes.. we need to redistribute BGP routes into IGP so that Lcation B Networks will be reachable via BGP and vice versa.

The best way to advertise the network into MPLS cloud is use network command instead of redistributing into BGP.

Redistribute BGP routes into OSPF, But advertise the OSPF routes into BGP via "Network" Command.

Example : Advertise Location A network into BGP via network command at the same device redistribute BGP routes into OSPF, The same thing vice vera in Location B side.

As per BGP rule, the network which we are advertising into BGP, that should be reachable via IGP then only that route will be installed into BGP routing table else it will be in BGP table not into BGP Routing Table.

so the traffic flow from Location A to Location B is like this

User Location A  ---(IGP)--- > CE(A side)--- Look up Destination in BGP Routing Table ---> MPLS CLoud --- > CE(B Side) --- (IGP) --- > User Location B.

Regards

Karuppu

New Member

Re: Replacing Point-Point T1 with MPLS Managed Circuit

Thanks Karuppu. What if the ISP gave me one single AS# for all my sites.

Will I need to run iBGP? Is it even neccessary? I just want the prefixes on RtrA to be seen on RtrB and vice versa so that they can communicate with each other.

Hall of Fame Super Gold

Re: Replacing Point-Point T1 with MPLS Managed Circuit

Ethernet handoff should mean you will have L2 connectivity.

Even if it is not that (L3 MPLS), it is not said you will have to configure BGP or other routing protocols to them.

Ask your SP for a detailed axplaination of the service given.

1562
Views
1
Helpful
5
Replies