MPLS Design Queries

[Steev112]

Hi,

I have MPLS rings Topology and no P as the scenario as follow

1. Head Office has two chassis 6500-VSS connected to access switches, Firewall and internet router as well as MPLS cloud.
2. All PEs connected to CEs.
3. All remote branches take the services from HQ (Internet, IP phone, application …).
4. I have one ISP connected to internet routers and will use default route to access internet no BGP

My Queries

1. C6500-VSS will be consider as Internet Gateway what is the configuration between the PE and this switch, can I consider these switch as CE?

Thanks for help in advanced

[Amit Goyal]

Hi,

>Yes VSS should be considered as CE.

>You can consider eBGP for connectivity between CE and PE. 

>You can use any IGP protocol on Head quarters for internal communication and do mutual redistribution of routes between IGP and eBGP.

>Originate a default route from Head quarters so that all internet traffic from remote CEs can go via Head Quarters only. 

HTH

-Amit

[Steev112]

Hi Amit,

Thanks for your reply, i will use OSPF between PE and CE each CE has different subsets and i have one VRF for all sites, and bellow the configuration 

router ospf 300 vrf INTRANET

network x.x.x.x x.x.x.x area 0
redistribute bgp 65530 subnets

My question is do i need to configure these parameters  under router ospf 300 vrf INTRANET :

1. Router ID.

2.  auto-cost reference-bandwidth.

3. max-metric router-lsa on-startup , timers throttle spf and timers lsa arrival

since i applied the above parameters when i configured IGP between PEs.

4. Do I need Domain ID?

5. do you recommend to use area 0 between PE to  CE or different area for each site?

thanks in advanced to help me for these quires?

[Amit Goyal · Accepted solution]

Hi Steven,

First of all check with your ISP if they are ready to support OSPF as PE-CE routing protocol. Because there is little complexity at provider end while using OSPF between PE-CE.

1. Router ID

Ans: Please do so as per your requirement. Otherwise router will choose an OSPF router ID its own.

2. auto-cost reference-bandwidth.

Ans: if you a link fatser then 100 Mb in your network and you want more granularity of metric. You can use this command.

3. max-metric router-lsa on-startup , timers throttle spf and timers lsa arrival

Ans: Since i applied the above parameters when i configured IGP between PEs.

4. Do I need Domain ID?

Ans: Domain tag is a loop prevention mechanism while using OSPF as PE-CE protocol.

Please refer below link.

http://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/118800-configure-ospf-00.html

If your network resembles to the scenario explained in above link, you can use Domain TAG/DN bit mechanism.

5. do you recommend to use area 0 between PE to CE or different area for each site?

Ans: I believe you can use are 0 on all sites.

You can go through below link as well.

https://networkinferno.net/ccie-study-ospf-sham-link

Please rate if it helped.

HTH

-Amit

[Steev112]

Thanks a lot for your help