Path Attributes; Figure 4: Routing Without Cidr; Figure 5: Routing With Cidr - Juniper BGP - CONFIGURATION GUIDE V 11.1.X Configuration Manual

JUNOSe 11.1.x BGP and MPLS Configuration Guide

Figure 4: Routing Without CIDR

With CIDR, the ISP can aggregate the routes as 192.168.128.0/17 and advertise a
single address to that prefix, as shown in Figure 5 on page 10.

Figure 5: Routing with CIDR

Path Attributes

A path attribute provides some additional information about a route. If a BGP speaker
has more than one route to the same destination prefix, it selects one of those routes
to use (the " best" route) based on the path attributes. BGP as implemented on the
Juniper Networks E Series Broadband Services Router specifies detailed and complex
criteria for picking the best route; this helps ensure that all routers will converge to
the same routing table, a necessary behavior to avoid routing loops. See "Selecting
the Best Path" on page 106 for more information.
10
Overview