My first of a series of posts for MPLS interoperability between Cisco’s IOS, Juniper’s Junos, and Brocade’s Netiron code. This post will use the same core I set up before:

L3 VPN is one of the more common applications for MPLS. This post will show a very basic three customer site. I’ll leave off all the advanced stuff for another post.

All three customers are connected to different PE routers. The PE and CE devices will run a routing protocol between then and advertise their loopback addresses to the core. This will emulate the customers LAN ranges.

I’m going to run BGP on R5 and R6 as the CE-PE routing protocol and OSPF on R7. The customer is running AS #65123 and the provider AS #100.

PE MP-BGP

The first thing we need to do is set up our MP-BGP peering between our PE routers. Let’s start off with IOS as it’s what most people know:

router bgp 100
 no bgp default ipv4-unicast
 neighbor 3.3.3.3 remote-as 100
 neighbor 3.3.3.3 update-source Loopback0
 neighbor 8.8.8.8 remote-as 100
 neighbor 8.8.8.8 update-source Loopback0
 !
 address-family vpnv4
  neighbor 3.3.3.3 activate
  neighbor 3.3.3.3 send-community extended
  neighbor 8.8.8.8 activate
  neighbor 8.8.8.8 send-community extended
 exit-address-family

Junos:

USER3:R3> show configuration routing-options
autonomous-system 100;

USER3:R3> show configuration protocols bgp
group L3VPN {
    type internal;
    local-address 3.3.3.3;
    family inet-vpn {
        unicast;
    }
    neighbor 4.4.4.4;
    neighbor 8.8.8.8;
}

Netiron:

router bgp
 local-as 100
 neighbor 3.3.3.3 remote-as 100
 neighbor 3.3.3.3 update-source 8.8.8.8
 neighbor 4.4.4.4 remote-as 100
 neighbor 4.4.4.4 update-source 8.8.8.8
!
 address-family vpnv4 unicast
 neighbor 3.3.3.3 activate
 neighbor 3.3.3.3 send-community extended
 neighbor 4.4.4.4 activate
 neighbor 4.4.4.4 send-community extended
 exit-address-family

Netiron is very similar to IOS when it comes to IGP/BGP. On all three we have simply created a vpnv4 BGP session between all three PE routers. We are not running the regular IPv4 address family on these sessions. Let’s confirm.
IOS:

7200_SRD_R4#sh bgp vpnv4 unicast all summary  | beg Nei
Neighbor        V    AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd
3.3.3.3         4   100      46      43       18    0    0 00:19:06        0
8.8.8.8         4   100      26      23       18    0    0 00:18:59        0

Junos:

USER3:R3> show bgp summary
Groups: 1 Peers: 2 Down peers: 0
Table          Tot Paths  Act Paths Suppressed    History Damp State    Pending
bgp.l3vpn.0            0          0          0          0          0          0
Peer                     AS      InPkt     OutPkt    OutQ   Flaps Last Up/Dwn State
4.4.4.4                 100         43         48       0       1       19:58 Establ
  bgp.l3vpn.0: 0/0/0/0
8.8.8.8                 100       3285       3241       0       0  1d 0:25:07 Establ
  bgp.l3vpn.0: 0/0/0/0

Netiron:

SSH@XMR_R8#sh ip bgp vpnv4 sum | beg AS#
  Neighbor Address  AS#         State   Time          Rt:Accepted Filtered Sent     ToSend
  3.3.3.3           100         ESTAB   1d 0h26m      2           0        0        0
  4.4.4.4           100         ESTAB   0h20m43s      0           0        0        0

All of our vpn4 sessions are now up.

CE-PE – R3-R6 – Junos

R6 is a regular BGP config so I’m not pasting it here. It is simply peering with AS #100 and advertising it’s loopback address. On Junos, you configure any ce-pe protocol under the routing instance you make for your customer:

USER3:R3> show configuration routing-instances
CUSTOMER1 {
    description "Our First Customer";
    instance-type vrf;
    interface fe-0/0/3.36;
    route-distinguisher 3.3.3.3:1;
    vrf-target target:100:1;
    protocols {
        bgp {
            group EXTERNAL {
                neighbor 10.0.2.13 {
                    family inet {
                        unicast;
                    }
                    peer-as 65123;
                }
            }
        }
    }
}

USER3:R3> show bgp summary instance CUSTOMER1
Groups: 1 Peers: 1 Down peers: 0
Table          Tot Paths  Act Paths Suppressed    History Damp State    Pending
CUSTO.inet.0           1          1          0          0          0          0
CUSTOM.mdt.0           0          0          0          0          0          0
Peer                     AS      InPkt     OutPkt    OutQ   Flaps Last Up/Dwn State
10.0.2.13             65123         93         98       0       0       40:54 Establ
  CUSTOMER1.inet.0: 1/1/1/0

USER3:R3> show route table CUSTOMER1 6.6.6.6

CUSTOMER1.inet.0: 6 destinations, 6 routes (6 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

6.6.6.6/32         *[BGP/170] 00:30:52, localpref 100
                      AS path: 65123 I
                    > to 10.0.2.13 via fe-0/0/3.36

CE-PE – R4-R7 – IOS

R7 is a simple OSPF config over area 0 advertising it’s loopback interface. The PE router is configured like so:

ip vrf CUS1
 rd 4.4.4.4:1
 route-target export 100:1
 route-target import 100:1
!
interface FastEthernet1/0.47
 encapsulation dot1Q 47
 ip vrf forwarding CUS1
 ip address 10.0.2.18 255.255.255.252
 ip ospf network point-to-point
 ip ospf 2 area 0
!
router ospf 2 vrf CUS1
 redistribute bgp 100 subnets
!
router bgp 100
 !
 address-family ipv4 vrf CUS1
  no synchronization
  redistribute ospf 2 vrf CUS1
 exit-address-family

7200_SRD_R4#sh ip ospf neighbor fa0/0.47

Neighbor ID     Pri   State           Dead Time   Address         Interface
7.7.7.7           0   FULL/  -        00:00:39    10.0.2.17       FastEthernet1/0.47

7200_SRD_R4#sh ip route vrf CUS1 7.7.7.7

Routing Table: CUS1
Routing entry for 7.7.7.7/32
  Known via "ospf 2", distance 110, metric 1, type intra area
  Redistributing via bgp 100
  Advertised by bgp 100
  Last update from 10.0.2.17 on FastEthernet1/0.47, 00:32:06 ago
  Routing Descriptor Blocks:
  * 10.0.2.17, from 7.7.7.7, 00:32:06 ago, via FastEthernet1/0.47
      Route metric is 1, traffic share count is 1

CE-PE – R8-R5 – Netiron

Standard config on the CE router once again. PE router configured as follows:

vrf CUS1
 rd 8.8.8.8:1
 address-family ipv4
   route-target export 100:1
   route-target import 100:1
 exit-address-family
exit-vrf
!
interface ve35
 vrf forwarding CUS1
 ip address 10.0.2.2/30
!
router bgp

 address-family ipv4 unicast vrf CUS1
 neighbor 10.0.2.1 remote-as 65123
 exit-address-family

SSH@XMR_R8#show ip bgp vrf CUS1 summary | beg AS#
  Neighbor Address  AS#         State   Time          Rt:Accepted Filtered Sent     ToSend
  10.0.2.1          65123       ESTAB   0h18m57s      1           0        4        0

SSH@XMR_R8#sh ip route vrf CUS1 5.5.5.5 | beg Des
        Destination        Gateway         Port          Cost          Type Uptime src-vrf
1       5.5.5.5/32         10.0.2.1        ve 35         20/0          Be   10m58s -

At this point each PE router is running their PE-CE protocol with their CE peer and learning the loopback address. Without configuring anything else, do we see any of the routes from the other PE devices?

USER3:R3> show route table CUSTOMER1 7.7.7.7

CUSTOMER1.inet.0: 6 destinations, 6 routes (6 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

7.7.7.7/32         *[BGP/170] 00:31:46, MED 1, localpref 100, from 4.4.4.4
                      AS path: ?
                    > to 10.0.4.14 via ae1.13, label-switched-path TO-R4

USER3:R3> show route table CUSTOMER1 5.5.5.5

CUSTOMER1.inet.0: 6 destinations, 6 routes (6 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

5.5.5.5/32         *[BGP/170] 00:21:03, localpref 100, from 8.8.8.8
                      AS path: 65123 I
                    > to 10.0.4.14 via ae1.13, label-switched-path TO-R8

Junos sees both loopbacks. Note too that the next-hops are both via LSPs. One to R4 and one to R8.

SSH@XMR_R8#show ip route vrf CUS1  6.6.6.6
Type Codes - B:BGP D:Connected I:ISIS O:OSPF R:RIP S:Static; Cost - Dist/Metric
BGP  Codes - i:iBGP e:eBGP
ISIS Codes - L1:Level-1 L2:Level-2
OSPF Codes - i:Inter Area 1:External Type 1 2:External Type 2 s:Sham Link
STATIC Codes - d:DHCPv6
        Destination        Gateway         Port          Cost          Type Uptime src-vrf
1       6.6.6.6/32         DIRECT          lsp TO-R3     200/0         Bi   42m12s -
SSH@XMR_R8#show ip route vrf CUS1 7.7.7.7
Type Codes - B:BGP D:Connected I:ISIS O:OSPF R:RIP S:Static; Cost - Dist/Metric
BGP  Codes - i:iBGP e:eBGP
ISIS Codes - L1:Level-1 L2:Level-2
OSPF Codes - i:Inter Area 1:External Type 1 2:External Type 2 s:Sham Link
STATIC Codes - d:DHCPv6
        Destination        Gateway         Port          Cost          Type Uptime src-vrf
1       7.7.7.7/32         DIRECT          lsp TO-R4     200/1         Bi   33m17s -

Netiron also sees both with a next-hop of each respective LSP.

7200_SRD_R4#sh ip route vrf CUS1 6.6.6.6

Routing Table: CUS1
Routing entry for 6.6.6.6/32
  Known via "bgp 100", distance 200, metric 0
  Tag 65123, type internal
  Redistributing via ospf 2
  Advertised by ospf 2 subnets
  Last update from 3.3.3.3 00:46:36 ago
  Routing Descriptor Blocks:
  * 3.3.3.3 (default), from 3.3.3.3, 00:46:36 ago
      Route metric is 0, traffic share count is 1
      AS Hops 1
      Route tag 65123
      MPLS Required
7200_SRD_R4#
7200_SRD_R4#sh ip route vrf CUS1 5.5.5.5

Routing Table: CUS1
Routing entry for 5.5.5.5/32
  Known via "bgp 100", distance 200, metric 0
  Tag 65123, type internal
  Redistributing via ospf 2
  Advertised by ospf 2 subnets
  Last update from 8.8.8.8 00:24:47 ago
  Routing Descriptor Blocks:
  * 8.8.8.8 (default), from 8.8.8.8, 00:24:47 ago
      Route metric is 0, traffic share count is 1
      AS Hops 1
      Route tag 65123
      MPLS Required

IOS has the routes, but there is an issue. IOS does not use the RSVP-TE tunnels for anything unless we tell it to. We can prove this to R5 like so:

7200_SRD_R4#sh ip cef vrf CUS1 5.5.5.5 detail
5.5.5.5/32, epoch 0
  recursive via 8.8.8.8 label 500000
    nexthop 10.0.4.10 FastEthernet1/0.24

Traffic would never hit the other PE routers. We need to ensure IOS actually uses these tunnels:

7200_SRD_R4#conf t
7200_SRD_R4(config)#int tun 0
7200_SRD_R4(config-if)#tunnel mpls traffic-eng autoroute announce
7200_SRD_R4(config-if)#int tun 1
7200_SRD_R4(config-if)#tunnel mpls traffic-eng autoroute announce

7200_SRD_R4#sh ip cef vrf CUS1 5.5.5.5 detail
5.5.5.5/32, epoch 0
  recursive via 8.8.8.8 label 500000
    nexthop 8.8.8.8 Tunnel1

So now our PE routers have all the required routes. They have also correctly installed these routes to go over the RSVP-TE tunnels. There is another issue to resolve though, and that’s the fact that R5 and R6 are in the same AS number. Remember with BGP, it uses the AS-PATH as a loop prevention mechanism. Therefore if R5 received a BGP update from it’s PE router with it’s own AS number in the path, that route will get dropped.
I can configure both CE routers to accept routes with their own AS number in like so:

USER5:R5> show configuration routing-options
autonomous-system 65123 loops 2;

R5 now sees R6′s route:

USER5:R5> show route 6.6.6.6

inet.0: 9 destinations, 9 routes (9 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

6.6.6.6/32         *[BGP/170] 00:03:04, localpref 100
                      AS path: 100 65123 I
                    > to 10.0.2.2 via ae1.35

But R6 still does not see R5′s route:

USER6:R6> show route 5.5.5.5

USER6:R6>

The reason why is more clear from R3, the PE’s perspective. Is R3 even advertising that route?

USER3:R3> show route advertising-protocol bgp 10.0.2.13

CUSTOMER1.inet.0: 6 destinations, 6 routes (6 active, 0 holddown, 0 hidden)
  Prefix                  Nexthop              MED     Lclpref    AS path
* 7.7.7.7/32              Self                                    ?
* 10.0.2.16/30            Self                                    ?

No it isn’t. Let’s go back to the Netiron and see if it was advertising everything over:

SSH@XMR_R8#sh ip bgp vrf CUS1 neighbors 10.0.2.1 advertised-routes
       There are 4 routes advertised to neighbor 10.0.2.1
Status A:AGGREGATE B:BEST b:NOT-INSTALLED-BEST E:EBGP I:IBGP L:LOCAL
       Prefix             Next Hop        MED        LocPrf     Weight Status
1      10.0.2.12/30       10.0.2.2                              0      BI
         AS_PATH: 100
2      10.0.2.16/30       10.0.2.2        0                     0      BI
         AS_PATH: 100
3      7.7.7.7/32         10.0.2.2        1                     0      BI
         AS_PATH: 100
4      6.6.6.6/32         10.0.2.2                              0      BI
         AS_PATH: 100 65123

The Netiron was always sending everything. Initially R5 was simply dropping those updates. As an optimisation, Junos will not bother advertising a route with the same AS path as the session as it knows the other side will just drop it. So why bother time advertising it to begin with? You need to specifically tell Junos to advertise under these circumstances:

USER3:R3# set routing-instances CUSTOMER1 protocols bgp group EXTERNAL advertise-peer-as

R6 now received the route:

USER6:R6> show route 5.5.5.5

inet.0: 13 destinations, 14 routes (13 active, 0 holddown, 1 hidden)
+ = Active Route, - = Last Active, * = Both

5.5.5.5/32         *[BGP/170] 00:00:20, localpref 100
                      AS path: 100 65123 I
                    > to 10.0.2.14 via ae1.36

That’s it for part one. If I don’t split this post I’ll never get it finished. If you’ve made it this far, congratulations! :)

You can find part 2 over here: http://mellowd.co.uk/ccie/?p=3456