NetworkTalk & BGP

A.7) Template A: basic BGP mulithoming configuration with 2 ISPs

Chapter A: BGP general notions, techniques and practices within an ISP

The following template which is very basic for many customers, describes the following configuration:

  • the router is connected to 2 isps,
  • inbound/Download traffic is not load balanced, active link is ISP-B’s one,
  • default upload traffic is going through ISP-B,
  • connectivity to ISP-C is done through multiple physical links which implies multiple sessions to the same ISP.
  • Physical Interfaces configuration : Note: The SDH interfaces have various options; the ones indicated below are of course not a reference. It can differ between ISPs.

1. interface Loopback0
description “LOOPBACK PEER 3xSTM1 AS-400 ISP-C”
ip address 11.11.226.250 255.255.255.255

2. POS1/1/1
description “STM4_1 ISP-C AS-400”
bandwidth 620000
ip address 30.30.31.22 255.255.255.252
load-interval 30
crc 32
clock source internal
pos ais-shut
pos framing sdh
pos scramble-atm
no cdp enable

3. interface POS1/1/2
description “STM4_2 ISP-C AS-400”
bandwidth 620000
ip address 30.30.31.26 255.255.255.252
load-interval 30
crc 32
clock source internal
pos ais-shut
pos framing sdh
pos scramble-atm
no cdp enable

4. interface POS1/1/3
description “STM4_3 ISP-C AS-400”
bandwidth 620000
ip address 30.30.31.30 255.255.255.252
load-interval 30
crc 32
clock source internal
pos ais-shut
pos framing sdh
pos scramble-atm
no cdp enable

5. interface POS3/0/0
description “STM16 ISP-B AS-300”
ip address 20.20.20.86 255.255.255.252
encapsulation ppp
load-interval 30
crc 32
pos framing sdh
!

6. interface Port-channel7
description “LINK TO Customer-G 11.11.224.3 ACTIVE”
ip address 11.11.224.2 255.255.255.224

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