MPLS vpnv4 mp-bgp

[B@B@r]

Dear  all,

        i am running MPLs vpnv4 using mp bgp.

my CA1 and CA2 both are running ospf  protocol on vrf CA and on PE router on both sides i redistribute the routes form ibgp to ospf and ospf to ibgp.

My question is that in CA routeing table the redistribution from iBGP routes should be E2 or E1 but the routes are O IA how come my vrf ospf knows that the redistribution from ibgp is basically O routes before IBGP.

thankx

[loris.marcellini · Accepted solution]

Hey there,

Background:

• MPLS backbone runs OSPF internally, it is also referred to as OSPF superbackbone (meaning you could even connect non-zero areas to it without incurring in LSA type 3 not being propagated).
• You could read more about the way OSPF works in MPLS but (https://supportforums.cisco.com/t5/mpls/superbackbone-ospf-domainin-mpls/td-p/306477) this is not the main reason why you see routes as IA.

Why you see routes as O IA:

• A parameter called OSPF domain-id comes into play here, (more at http://wiki.kemot-net.com/mpls-vpn-ospf#toc3) for instance if domain-id matches between the OSPF peers' routes then those routes will be seen as IA a not as E1/2 anymore.

PS:

For academic purpose, If I were you I would also take a look at how the sham-link works and how that would play a role in this scenario.

Hope this helps, L.

[B@B@r]

Thank-you for such a nice explanation.
so can we check the domain-id which matches OSPF peers Routes when they are carrying by BGP. i mean directly some show command of BGP which tell us that these BGP routes are from OSPF and its domain-id as that.

[loris.marcellini · Accepted solution]

yup! the following show command shows domain-id set for the specific route (I have replaced real subnets and info wit letters):

show ip bgp vpnv4 vrf Test x.x.x.x/xx

BGP routing table entry for rd:x.x.x.x/xx, version x
Paths: (1 available, best #1, table Test)
Flag: 0x820
  Not advertised to any peer
  Local
   y.y.y.y (metric N) from y.y.y.y(y.y.y.y)
      Origin incomplete, metric 0, localpref 100, valid, internal, best
      Extended Community: RT:rt OSPF DOMAIN ID:domain-id
        OSPF RT:0.0.0.0:2:0 OSPF ROUTER ID:f.f.f.f
        mpls labels in/out nolabel/19

[B@B@r]

sound great!!!!
what are the other four types and what if we change the type manually?
why ospf choose domain ID type 0x0005 by default?
0005 Type 0x0005
0105 Type 0x0105
0205 Type 0x0205
8005 Type 0x8005

and can we run eigrp as IGP ?

[loris.marcellini]

DOMAIN-ID is locally computed based on several OSPF parameters, to make it match with your peer, you must run OSPF with the same process ID and area on both sides. It cannot be manually set AFAIK.

Hope this helps. L.

[B@B@r]

[loris.marcellini]

super! I did not remember It could.