Controlling MPLS Label Distribution – Video
I was looking through my archives to remember how to configure “controlling label distribution” and realised that I had not not made a video for this subject, so here goes.
Consider the topology below.
As we all know, LDP assigns a Label for each IGP prefix and connected route in the RIB. Therefore when we use the “Control label distribution” feature we need to ensure the ACL we use, contains an access control entry(ACE) for the neighboring loopbacks. Each Label Switch Router(LSR) then advertises a label binding for each loopback.
Lets take R3s loopback for example. R3 advertises a label for its loopback to R2. R2 has an ACE for R3s loopback and therefore sends a label to R1. R1 now has an end to end LSP to R3. If on R2 you did not have an ACE for R3s loopback, you are effectivly breaking the LSP.
Watch how to configure it below, or download it and watch in on your iPod or iPhone.
The commands used in the above video can be seen below.
R1
!
no mpls ldp advertise-labels
mpls ldp advertise-labels for LOOPBACK0
mpls label protocol ldp
!
interface Loopback0
ip address 1.1.1.1 255.255.255.255
!
interface FastEthernet1/1
ip address 10.0.0.1 255.255.255.252
ip ospf network point-to-point
mpls ip
!
router ospf 1
router-id 1.1.1.1
network 1.1.1.1 0.0.0.0 area 0
network 10.0.0.0 0.0.0.3 area 0
!
ip access-list standard LOOPBACK0
permit 1.1.1.1
permit 2.2.2.2
permit 3.3.3.3
!
mpls ldp router-id Loopback0
!
R2
!
no mpls ldp advertise-labels
mpls ldp advertise-labels for LOOPBACK0
mpls label protocol ldp
!
interface Loopback0
ip address 2.2.2.2 255.255.255.255
!
interface FastEthernet1/0
ip address 10.0.0.2 255.255.255.252
ip ospf network point-to-point
mpls ip
!
interface FastEthernet1/1
ip address 10.0.0.5 255.255.255.252
ip ospf network point-to-point
mpls ip
!
ip access-list standard LOOPBACK0
permit 2.2.2.2
permit 3.3.3.3
permit 1.1.1.1
!
mpls ldp router-id Loopback0
!
R3
!
no mpls ldp advertise-labels
mpls ldp advertise-labels for LOOPBACK0
mpls label protocol ldp
!
interface Loopback0
ip address 3.3.3.3 255.255.255.255
!
interface FastEthernet1/0
ip address 10.0.0.6 255.255.255.252
ip ospf network point-to-point
mpls ip
!
router ospf 1
router-id 3.3.3.3
log-adjacency-changes
network 3.3.3.3 0.0.0.0 area 0
network 10.0.0.4 0.0.0.3 area 0
!
ip access-list standard LOOPBACK0
permit 3.3.3.3
permit 1.1.1.1
permit 2.2.2.2
!
mpls ldp router-id Loopback0
Great video Zarar, hope to see more on CCIE SP, as I am heading to this test.
Hi Artur
Time is not on my side at the moment, give me a week or so and i’ll be back on the case.
Zarar