Lenovo ThinkSystem NE2552E, Application Manual

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NE2552E Application Guide for ENOS 8.4
BGP Failover Configuration
Use the following example to create redundant default gateways for a NE2552E at
a Web Host/ISP site, eliminating the possibility, should one gateway go down, that
requests will be forwarded to an upstream router unknown to the switch.
As shown in Figure 39 , the switch is connected to ISP 1 and ISP 2. The customer
negotiates with both ISPs to allow the switch to use their peer routers as default
gateways. The ISP peer routers will then need to announce themselves as default
gateways to the NE2552E.
Figure 39.
BGP Failover Configuration Example
On the NE2552E, one peer router (the secondary one) is configured with a longer
AS path than the other, so that the peer with the shorter AS path will be seen by the
switch as the primary default gateway. ISP 2, the secondary peer, is configured
with a metric of “3,” thereby appearing to the switch to be three router hops away.
1.
Define the VLANs.
For simplicity, both default gateways are configured in the same VLAN in this
example. The gateways could be in the same VLAN or different VLANs
.
2.
Define the IP interfaces with IPv4 addresses.
The switch will need an IP interface for each default gateway to which it will be
connected. Each interface must be placed in the appropriate VLAN. These
interfaces will be used as the primary and secondary default gateways for the
switch.
ISP 1
AS 100
BladeCenter
Server 1
IP: 200.200.200.10
Server 2
IP: 200.200.200.11
IP: 200.200.200.1
IP: 210.210.210.1
ISP 2
AS 200
Peer 1 Router
(Primary)
IP:200.200.200.2
Default gateway,
with routes having
shorter AS PATH
GbE Switch Module
announces routes with
metric of “3”
Peer 2 Router
(Secondary)
IP:210.210.210.2
Metric = AS path
length (metric of ‘3’) = local
AS repeated 3 times
NE2552E(config)# vlan 1
NE2552E(config)# interface ip 1 address 200.200.200.1 255.255.255.0 enable
NE2552E(config-ip-if)# exit
NE2552E(config)# interface ip 2 address 210.210.210.1 255.255.255.0 enable
NE2552E(config-ip-if)# exit