Use the following procedure to create an AS Path Access List:

config
   context context_name
      ip as-path access-list list_name [ { deny | permit } reg_expr ]

Notes:

Use the following configuration example to create a Route Map:

config
   context context_name
      route-map map_name { deny | permit } seq_number

Notes:

The example below shows a configuration that creates two route access lists, applies them to a route map, and uses that route map for a BGP router neighbor.

The example below shows a configuration that creates two route access lists, applies them to a route map, and uses that route map for a BGP router neighbor.

config
   context isp1
      route-access-list named RACLin1a permit 88.151.1.0/30
      route-access-list named RACLin1a permit 88.151.1.4/30
      route-access-list named RACLany permit any
      route-map RMnet1 deny 100
         match ip address route-access-list RACLin 1 a
         #exit
         route-map RMnet1 deny 200
         match ip address route-access-list RACLin 1 b
         #exit
      route-map RMnet1 permit 1000
         match ip address route-access-list RACLany
         #exit
      router bgp 1
         neighbor 152.20.1.99 as-path 101
         neighbor 152.20.1.99 route-map RMnet1

To add static routes to a context configuration, you must know the names of the interfaces that are configured in the current context. Use the show ip interface command to list the interfaces in the current context (Exec mode).

Information for all interfaces configured in the current context is displayed as shown in the following example.

[local]host_name# show ip interface
Intf Name: Egress 1
Description:
IP State: Up (Bound to slot/port untagged ifIndex 402718721)
IP Address: 192.168.231.5
Subnet Mask: 255.255.255.0
Bcast Address: 192.168.231.255
MTU: 1500
Resoln Type: ARP          ARP timeout: 3600 secs
L3 monitor LC-port switchover: Disabled 
Number of Secondary Addresses: 0
Total interface count: 1

The first line of information for each interface lists the interface name for the current context as shown in the example output. In this example, there is one interface with the name Egress 1.

config
   context context_name
      ip route { ip_address [ ip_mask ] | ip_addr_mask_combo } { next-hop next_hop_address | egress_name [ precedence precedence [ cost cost ] 

Notes:

Use the following configuration example to remove static routes from a context's configuration:

config
   context context_name
       no ip route { ip_address ip_mask | ip_addr_mask_combo } next_hop_address egress_name [ precedence precedence ] [ cost cost ]

Notes

OSPF is a link-state routing protocol that employs an interior gateway protocol (IGP) to route IP packets using the shortest path first based solely on the destination IP address in the IP packet header. OSPF routed IP packets are not encapsulated in any additional protocol headers as they transit the network.

An Autonomous System (AS), or Domain, is defined as a group of networks within a common routing infrastructure.

OSPF is a dynamic routing protocol that quickly detects topological changes in the AS (such as router interface failures) and calculates new loop-free routes after a period of convergence. This period of convergence is short and involves a minimum of routing traffic.

In a link-state routing protocol, each router maintains a database, referred to as the link-state database, that describes the Autonomous System's topology. Each participating router has an identical database. Each entry in this database is a particular router's local state (for example, the router's usable interfaces and reachable neighbors). The router distributes its local state throughout the AS by flooding.

All routers run the same algorithm in parallel. From the link-state database, each router constructs a tree of shortest paths with itself as root to each destination in the AS. Externally derived routing information appears on the tree as leaves. The cost of a route is described by a single dimensionless metric.

OSPF allows sets of networks to be grouped together. Such a grouping is called an area. The topology of this area is hidden from the rest of the AS, which enables a significant reduction in routing traffic. Also, routing within the area is determined only by the area's own topology, lending the area protection from bad routing data. An area is a generalization of an IP subnetted network.

OSPF enables the flexible configuration of IP subnets so that each route distributed by OSPF has a destination and mask. Two different subnets of the same IP network number may have different sizes (that is, different masks). This is commonly referred to as variable-length subnetting. A packet is routed to the best (longest or most specific) match. Host routes are considered to be subnets whose masks are "all ones" (0xffffffff).

OSPF traffic can be authenticated or non-authenticated, or can use no authentication, simple/clear text passwords, or MD5-based passwords. This means that only trusted routers can participate in the AS routing. You can specify a variety of authentication schemes and, in fact, you can configure separate authentication schemes for each IP subnet.

Externally derived routing data (for example, routes learned from an exterior protocol such as BGP) is advertised throughout the AS. This externally derived data is kept separate from the OSPF ink state data.

Each external route can also be tagged by the advertising router, enabling the passing of additional information between routers on the boundary of the AS.

OSPF uses a link-state algorithm to build and calculate the shortest path to all known destinations.

This section describes how to implement basic OSPF routing.

Much of OSPF version 3 is the same as OSPF version 2. OSPFv3 expands on OSPF version 2 to provide support for IPv6 routing prefixes and the larger size of IPv6 addresses. OSPFv3 dynamically learns and advertises (redistributes) IPv6 routes within an OSPFv3 routing domain

In OSPFv3, a routing process does not need to be explicitly created. Enabling OSPFv3 on an interface will cause a routing process and its associated configuration to be created.

This section describes how to implement basic OSPF routing.

To confirm the OSPF router configuration, use the following command and look for the section labeled router ipv6 ospf in the screen output:

show config context ctxt_name [ verbose ]

Mobile devices communicate to the Internet through Home Agents (HAs). HAs assign IP addresses to the mobile node from a configured pool of addresses. These addresses are also advertised to Internet routers through an IP routing protocol to ensure dynamic routing. The BGP-4 protocol is used as a monitoring mechanism between an HA and Internet router with routing to support Interchassis Session Recovery (ICSR). (Refer to Interchassis Session Recovery for more information.)

The objective of BGP-4 protocol support is to satisfy routing requirements and monitor communications with Internet routers. BGP-4 may trigger an active to standby switchover to keep subscriber services from being interrupted.

The following BGP-4 features are supported:

IP pool routes and loopback routes are advertised in the BGP domain in the following ways:

This section describes how to configure and enable basic BGP routing support in the system.

config
   context context_name
      router bgp AS_number
         neighbor ip_address remote-as AS_num

Notes:

Redistributing routes into BGP simply means that any routes from another protocol that meet a specified criterion, such as a route type, or a rule within a route-map, are redistributed through the BGP protocol to all BGP areas. This is an optional configuration.

config
   context context_name
      router bgp as_number
         redistribute bgp { bgp | connected | static } [ metric  metric_value ] [ metric-type { 1 | 2 } ] [ route-map  route_map_name ]

Notes:

Route filtering based on a BGP community or extended community (route target) is configured via CLI Route Map Configuration mode commands.