10-08-2008 12:43 AM - edited 03-03-2019 11:50 PM
2 mpls wan link , getting terminated on 2 different routers. each router connected to a single 6509 siwtch.
so router A---6509 A and router B ---6509 B
6509 A --- 6509 B --HSRP
the routers A and B are going to exchange routes with providers routers running bgp respectively.They have thier own data path
the 6509 are LAN gateways and will do routing.
how to achieve?
preferred routing via 6509
say subnet A to use route path via router A
say subnet B to use route path via router B
also redundancy in case if
6509 A fails
6509 B fails
router A fails or the MPLS link to which it is connected
router B fails or the MPLS link to which it is connected
Which routing protocol to select
can it be OSPF between all 4 devices
or IBGP between all 4 devices and run ospf between 6509
Thanks
10-08-2008 04:39 PM
Assuming your EBGP isn't Internet, you might run both OSPF and IBGP on all four routers. All four then would "know" both inside and outside topologies and there would be no need to redistribute between OSPF and BGP.
If possible, would avoid preferred paths. Likely this could be supported via PBR, but often a maintenance headache. You could consider using OER/PfR on routers A and B so that, at least for outbound, best performance path would be chosen and/or dynamically load balance outbound links.
You could also consider using GLBP on LAN 6500s instead of HSRP.
10-09-2008 02:43 AM
Thanks
No its not internet
i m not sure why to use both protocols on all 4 routers. can u pls ellaborate
cant i achieve LB and failover using routing protocols, is it compulsory to use OEF/PfR
10-09-2008 03:23 AM
"cant i achieve LB and failover using routing protocols, is it compulsory to use OEF/PfR"
No and no. (Note your first question was a negative.)
"i m not sure why to use both protocols on all 4 routers. can u pls ellaborate "
You don't have to run both protocols on all 4 routers. You will need to run EBGP on routers A and B, I assume, to peer with external provider routers. There's probably benefit to using OSPF for your internal routing protocol. If you're going to run both protocols, your left with the issue of making internal routes known to the routers A and B and BGP external routes known to 6500s A and B. There are different ways of doing this, usually doing some form of redistribution, or you could even use statics, but if you run both OSPF and BGP on all routers, all 4 routers will dynamically "know" both the inside and outside topologies.
PS:
If you use EBGP internally, one issue that might arrise is Cisco BGP's default of only placing one path in route table. You can adjust this using multipath, but not 100% certain IBGP will then automatically install multiple paths in route table.
10-09-2008 06:49 AM
Hello Munaf,
just to add to what Joseph had written:
use OSPF on all four routers
have RA and RB have eBGP sessions and iBGP session between them
Have RA and RB to generate in OSPF a default-route of type O E1 in this way you can satisfy all your requirements
In normal conditions C6509A will exit via RA and C6509B via RB in case of failures the recovery will be managed by OSPF and the iBGP session.
As a plus you could have a route-map to have the O E1 default-route sent out if the eBGP session is active (check the presence of a BGP default-route with a specific BGP next-hop)
router ospf 10
default-information originate route-map check-bgp
access-list 10 permit 0.0.0.0
access-list 20 permit host
route-map check-bgp permit 10
match ip address 10
match ip next-hop 20
set metric-type type-1
set metric 50
Do this on both routers RA and RB with the correct eBGP next-hop in each case we used this for some years in a network
Hope to help
Giuseppe
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