Underlay Network
Physical Connectivity Diagram
Description of the Physical Layer
The Underlay represents the IP/MPLS connectivity between the BNG MASTER and SLAVE, the L3 connections to the Carriers, and the L2 connections to the OLT and auxiliary services.
Underlay IP Addressing
Inter-BNG (IS-IS/LDP/iBGP)
| Segment | Grid | BNG MASTER | BNG SLAVE |
|---|---|---|---|
| Inter-BNG | 172.99.1.0/31 | .0 | .1 |
| Loopback | /32 | 10.0.0.1 | 10.0.0.2 |
| Redundant IF | 192.168.12.0/31 | .0 | .1 |
BNG to Carrier 1 (172.16.1.x/31)
| Segment | Grid | BNG | Carrier 1 |
|---|---|---|---|
| MASTER → C1 | 172.16.1.0/31 | .0 | .1 |
| SLAVE → C1 | 172.16.1.2/31 | .2 | .3 |
BNG to Carrier 2 (172.16.2.x/31)
| Segment | Grid | BNG | Carrier 2 |
|---|---|---|---|
| MASTER → C2 | 172.16.2.0/31 | .0 | .1 |
| SLAVE → C2 | 172.16.2.2/31 | .2 | .3 |
BNG to LIG
| Segment | Grid | BNG | LIG |
|---|---|---|---|
| MASTER → LIG | 172.19.1.0/30 | .2 | .1 |
| SLAVE → LIG | 172.20.1.0/30 | .2 | .1 |
Routing Protocols
IS-IS (Inter-BNG)
The link between BNG MASTER and SLAVE runs IS-IS Level 2 as the routing protocol for the MPLS underlay:
/configure router "Base" isis 0 admin-state enable
/configure router "Base" isis 0 level-capability 2
/configure router "Base" isis 0 area-address [49.0001]
/configure router "Base" isis 0 interface "system" admin-state enable
/configure router "Base" isis 0 interface "to_SLAVE" admin-state enable
/configure router "Base" isis 0 interface "to_SLAVE" interface-type point-to-point
LDP (MPLS Label Distribution)
LDP is used to establish LSPs between BNGs, necessary for the redundant-interface SDP and VPN-IPv4/v6 transport:
/configure router "Base" ldp interface-parameters interface "to_SLAVE" admin-state enable
/configure router "Base" ldp targeted-session peer 10.0.0.2 admin-state enable
iBGP (VPN-IPv4/v6)
iBGP between loopbacks carries the VPN-IPv4 and VPN-IPv6 routes of VPRNs 9998 and 9999:
/configure router "Base" bgp group "iBGP" admin-state enable
/configure router "Base" bgp group "iBGP" type internal
/configure router "Base" bgp group "iBGP" local-address 10.0.0.1
/configure router "Base" bgp group "iBGP" family vpn-ipv4 true
/configure router "Base" bgp group "iBGP" family vpn-ipv6 true
/configure router "Base" bgp group "iBGP" local-as as-number 65510
BNG Port Configuration
| Port | Encapsulation | Destination | Function |
|---|---|---|---|
| 1/1/c1/1 | dot1q | BNG Peer | IS-IS/LDP/iBGP |
| 1/1/c2/1 | qinq | OLT | Subscriber access + SRRP |
| 1/1/c3/1 | dot1q | LIG | Lawful Interception |
| 1/1/c4/1 | hybrid | DNS64 | DNS64 for NAT64 |
| 1/1/c5/1 | dot1q | Carrier 1 | eBGP upstream |
| 1/1/c6/1 | dot1q | Carrier 2 | eBGP upstream |