In this example, we will configure Eigrp as the PE-CE routing protocol in Mpls Vpn Environment.We will also explain POI(point of Insertion), Cost Community and SoO (Site of Origin) briefly.
Here is our topology:
PE-1 configuration:
ip vrf a
rd 1:1
route-target export 1:1
route-target import 1:1
interface Loopback0
ip address 1.1.1.1 255.255.255.255
interface Loopback100
ip vrf forwarding a
ip address 100.100.100.1 255.255.255.255
interface FastEthernet1/0
ip address 192.168.12.1 255.255.255.0
ip ospf network point-to-point
mpls ip
interface FastEthernet1/1
ip address 192.168.13.1 255.255.255.0
ip ospf network point-to-point
mpls ip
interface FastEthernet2/0
ip vrf forwarding a
ip address 10.10.1.1 255.255.255.0
router eigrp 100
auto-summary
address-family ipv4 vrf a
redistribute bgp 1
network 0.0.0.0
default-metric 10000 1000 255 1 1500
no auto-summary
autonomous-system 101
exit-address-family
router ospf 1
log-adjacency-changes
network 1.1.1.1 0.0.0.0 area 0
network 192.168.0.0 0.0.255.255 area 0
!
router bgp 1
no synchronization
bgp router-id 1.1.1.1
bgp log-neighbor-changes
neighbor 2.2.2.2 remote-as 1
neighbor 2.2.2.2 update-source Loopback0
no auto-summary
!
address-family vpnv4
neighbor 2.2.2.2 activate
neighbor 2.2.2.2 send-community extended
exit-address-family
!
address-family ipv4 vrf a
redistribute connected
redistribute static
redistribute eigrp 101
no synchronization
exit-address-family
PE-2 Configuration:
ip vrf a
rd 1:1
route-target export 1:1
route-target import 1:1
interface Loopback0
ip address 3.3.3.3 255.255.255.255
interface Loopback100
ip vrf forwarding a
ip address 100.100.100.3 255.255.255.255
interface FastEthernet1/0
ip address 192.168.23.3 255.255.255.0
ip ospf network point-to-point
mpls ip
interface FastEthernet1/1
ip address 192.168.13.3 255.255.255.0
ip ospf network point-to-point
duplex auto
speed auto
mpls ip
interface FastEthernet2/1
ip vrf forwarding a
ip address 10.10.3.3 255.255.255.0
router eigrp 100
auto-summary
address-family ipv4 vrf a
redistribute bgp 1
network 0.0.0.0
default-metric 10000 1000 255 1 1500
no auto-summary
autonomous-system 101
exit-address-family
router ospf 1
log-adjacency-changes
network 3.3.3.3 0.0.0.0 area 0
network 192.168.0.0 0.0.255.255 area 0
router bgp 1
no synchronization
bgp router-id 3.3.3.3
bgp log-neighbor-changes
neighbor 2.2.2.2 remote-as 1
neighbor 2.2.2.2 update-source Loopback0
no auto-summary
address-family vpnv4
neighbor 2.2.2.2 activate
neighbor 2.2.2.2 send-community extended
exit-address-family
address-family ipv4 vrf a
redistribute connected
redistribute static
redistribute eigrp 101
no synchronization
exit-address-family
CE-1 Configuration:
interface Loopback0
ip address 7.7.7.7 255.255.255.255
interface FastEthernet0/0
ip address 10.10.1.7 255.255.255.0
interface FastEthernet0/1
description *** Backdoor Link ***
bandwidth 1000
ip address 10.10.78.7 255.255.255.0
router eigrp 101
redistribute static
network 0.0.0.0
default-metric 10000 1000 255 1 1500
no auto-summary
ip route 70.70.70.70 255.255.255.255 Null0
CE-2 Configuration:
interface Loopback0
ip address 8.8.8.8 255.255.255.255
interface FastEthernet0/0
ip address 10.10.3.8 255.255.255.0
interface FastEthernet0/1
description *** Backdoor Link ***
bandwidth 1000
ip address 10.10.78.8 255.255.255.0
router eigrp 101
redistribute static
network 0.0.0.0
default-metric 10000 1000 255 1 1500
no auto-summary
ip route 80.80.80.80 255.255.255.255 Null0
BGP Extended Communities for EIGRP
0x8800 Flags + TAG
0x8801 Autonomous System + Delay
0x8802 Route metric information Reliability + Hop Count + BW
0x8803 Reserved field + Load + MTU
0x8804 Remote Autonomous System + Remote ID
0x8805 Remote Protocol + Remote Metric
The POI (point of insertion) is pre-bestpath.
Cost Community is considered in BGP path selection process before any other comparision steps. Cost community for EIGRP over MPLS VPN is turned on automatically in the case of EIGRP as thePE-CE routing protocol. The costcommunity ID is either 128 or 129.
- 128 for EIGRP internal routes
- 129 for EIGRP external routes
The path with the lowest Eigrp cost is prefered.So internal routes are prefered over external routes.
Lets check route and BGP tables for vrf a on PE-1:
PE-1#show ip route vrf a
Routing Table: a
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route
Gateway of last resort is not set
100.0.0.0/32 is subnetted, 3 subnets
B 100.100.100.4 [200/0] via 4.4.4.4, 00:54:58
C 100.100.100.1 is directly connected, Loopback100
B 100.100.100.3 [200/0] via 3.3.3.3, 00:54:58
70.0.0.0/32 is subnetted, 1 subnets
D EX 70.70.70.70 [170/514560] via 10.10.1.7, 00:18:11, FastEthernet2/0
80.0.0.0/32 is subnetted, 1 subnets
B 80.80.80.80 [200/514560] via 3.3.3.3, 00:18:05
7.0.0.0/32 is subnetted, 1 subnets
D 7.7.7.7 [90/156160] via 10.10.1.7, 00:22:21, FastEthernet2/0
8.0.0.0/32 is subnetted, 1 subnets
D 8.8.8.8 [90/2716160] via 10.10.1.7, 00:12:42, FastEthernet2/0
10.0.0.0/24 is subnetted, 4 subnets
C 10.10.1.0 is directly connected, FastEthernet2/0
B 10.10.3.0 [200/0] via 3.3.3.3, 00:25:24
B 10.10.4.0 [200/30720] via 3.3.3.3, 00:16:23
D 10.10.78.0 [90/2588160] via 10.10.1.7, 00:12:52, FastEthernet2/0
PE-1#show ip bgp vpnv4 vrf a
BGP table version is 85, local router ID is 1.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
Route Distinguisher: 1:1 (default for vrf a)
*> 7.7.7.7/32 10.10.1.7 156160 32768 ?
*> 8.8.8.8/32 10.10.1.7 2716160 32768 ?
*> 10.10.1.0/24 0.0.0.0 0 32768 ?
*>i10.10.3.0/24 3.3.3.3 0 100 0 ?
*>i10.10.4.0/24 3.3.3.3 30720 100 0 ?
*> 10.10.78.0/24 10.10.1.7 2588160 32768 ?
*> 70.70.70.70/32 10.10.1.7 514560 32768 ?
*>i80.80.80.80/32 3.3.3.3 514560 100 0 ?
*> 100.100.100.1/32 0.0.0.0 0 32768 ?
*>i100.100.100.3/32 3.3.3.3 0 100 0 ?
*>i100.100.100.4/32 4.4.4.4 0 100 0 ?
7.7.7.7/32 is internal Eigrp route.So cost community id should be 128
PE-1#show ip bgp vpnv4 vrf a 7.7.7.7
BGP routing table entry for 1:1:7.7.7.7/32, version 59
Paths: (1 available, best #1, table a)
Advertised to update-groups:
1
Local
10.10.1.7 from 0.0.0.0 (1.1.1.1)
Origin incomplete, metric 156160, localpref 100, weight 32768, valid, sourced, best
Extended Community: RT:1:1 Cost:pre-bestpath:128:156160 0x8800:32768:0
0x8801:101:130560 0x8802:65281:25600 0x8803:65281:1500
mpls labels in/out 25/nolabel
70.70.70.70/32 is internal Eigrp route.So cost community id should be 129
PE-1#show ip bgp vpnv4 vrf a 70.70.70.70
BGP routing table entry for 1:1:70.70.70.70/32, version 65
Paths: (1 available, best #1, table a)
Advertised to update-groups:
1
Local
10.10.1.7 from 0.0.0.0 (1.1.1.1)
Origin incomplete, metric 514560, localpref 100, weight 32768, valid, sourced, best
Extended Community: RT:1:1 Cost:pre-bestpath:129:514560 0x8800:0:0
0x8801:101:258560 0x8802:65281:256000 0x8803:65281:1500
0x8804:0:117901063 0x8805:3:0
mpls labels in/out 27/nolabel
When the router receives a route across the interface with this route map configured and the SoO(Site of origin) of the route matches the configured SoO the router rejects the route.SoO helps to speed up the convergence when a route disappears.
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