"P" Routers on the Ring

[junaide45]

For MPLS netwrok, why it is necessary or recommended to have only "P" Routers on your main e.g: 10G link

Why it is not recommended to have "PE" routers connected as part of Metro Ring??

[rais]

It's not necessary that your P be connected to 10G/main links. It's quite possible [and very much common] that none of your routers are purely P routers. All routers in the network could be PE and P at the same time, with each acting as P for certain LSPs and PE for others.

HTH.

[junaide45]

ahan, but m scenario is ... we have 2 PE routes connected in the middle of 2 seperate P; and they are part of the ring

CE1 ---- PE3 ---- P1 ----- PE1 ---- PE2 ---- P2 ---- PE4 --- CE2

PE2 in this topology must be working P also; and should forward packets without checking whether PE2 own that routes of particular (RT) or not

But I have observed, for some vrf which PE2 doesn't have any connected routes, is discarding the routes

as work around I created dummy interface belonging this vrf so it can have atleast one connected route belong to that vrf

does that makes? is it possible or am i missing something

Thanks for help

[rais]

I'm not getting 'Discarding the routes'? You do have PE3 and PE4 as iBGP neighbors...right?

Rais.

[junaide45]

CE1 ---- PE3 ---- P1 ----- PE1 ---- PE2 ---- P2 ---- PE4 --- CE2

                          |                                  |

                         P4 -------------PE5---------- P3

all these routers are part if same iBGP cloud, P1, P2, P3 and P4 are working as RR (ipv4 & vpnv4),

ospf is running between PE4 and CE2

and similarly ospf PE3 and CE1 ... under same vrf VPNA

mainly the traffic is flowing from CE1 to CE4 via .... PE5 path because of less isis-metric and PE5 also have connected routes of VPNA

when this link (of PE5) goes down; traffic starts flowing from P1 ----- PE1 ---- PE2 ---- P2 path

PE1 has connected routes of but PE2 doesnt have connected routes of VPN4

when traffic flows from P1 ----- PE1 ---- PE2 ---- P2 path; PE2 will check RT of VPN4 and will check that it doesnt have connected routes of VPN4, so it will not forward traffic to next hop

so when I configured one interface having connected routes of VPNA in PE2; traffic related to VPNA start flowing from CE1 to CE2 ... and where ever VPNA routes are required

This is actually my observation, this is merely my observation

This what I did as work around to solve the problme

[shreerampardhy]

Hello Muhammad,

If you want the PE router to accept the RTs which are not configured on it then you can enable command

no bgp default route-target filter

But I am a bit lost on how you have implemented your solution.

From what i understand, you are using All the P routers as RRs.

The PE routers have BGP sessions with the RRs only, while the RRs have full mesh.

Since PE2 is not reflecting the VPNV4 routes, there is no need to have the router configured with the vrf to accept the RTs.