Figure 15-5 illustrates a few issues you may encounter when running common industry-standard routing protocols among Juniper and Cisco routers. In this figure, devices from different vendors have been mixed in a rather haphazard way to trigger certain issues that we want to address. The figure does not necessarily reflect a layered or site-based approach to multivendor networks.
Figure 15-5. Base topology for IGP and BGP interoperability concerns
In Figure 15-5,
r5 share OSPF adjacencies, which use MD5
authentication, and Internal BGP (IBGP) relationships within AS 64512.
r5 is an External BGP (EBGP)
r1 in AS 100. Routers
EBGP peers to
r4 in AS 400.
In this example, we assume that AS 64512 contains other Cisco
devices that are connected in a partial mesh. Router
r5 represents the collection of Cisco
Before bringing up OSPF or BGP relationships among the Cisco and
Juniper devices, we must first establish simple Layer 3 connectivity.
Assuming that all physical cabling is in place, we add the necessary
configuration elements for the Cisco–Juniper connections on
r5. This snippet shows Fast Ethernet
0/1 configured with appropriate IP addresses
for connectivity to
r2. We also see the appropriate address for
0/0 and confirm that a loopback ...