Importing Routes from Global Table into a VRF Table

Every time I saw that we leake route from VRF to global routing table, So VRF can use the Global routing table for Internet Accsess ( Internet over L3 VPN ) or for specific network access.

But heere we are going to see that If we want to import routes from Global routing table to VRF then how  we can configure the network device .

Using the feature know as Import Route Map  ( import ipv4 unicase | multicast )

The BGP Support to Import routes  from Global Table into a VRF Table feature introduces the capability to import IPv4 unicast prefixes from the global routing table into a Virtual Private Network (VPN) routing/forwarding instance (VRF) table using an import route map.

Below is the Example :

ip prefix-list chetan seq 10 permit x.x.x.x/x


ip prefix-list chetan seq 20 permit x.x.x.x/x
ip prefix-list chetane seq 30 permit x.x.x.x/x
!

ip vrf ckumar
rd 50:1

import ipv4 unicast map CHETAN_IMPORT
route-target export 50:1

route-target import 50:1

!

exit

!

route-map CHETAN_IMPORT permit 10

match ip address prefix-list chetan

SSO/NSF with GR and / or NSR

Some definitions


HA- High AvailabilityHigh level terminology

SSO -StatefulSwitchover

StatefulSwitchoverAn operating mode where a dual processor router has transferred state information to a standby processor to allow the standby to pickup necessary router functions in the event of an active failure. Mostly refers to L2 information (PPP state, FIB ect) but some L3 applicability. In this operating mode both processors must run identical software versions.


NSF-Non Stop ForwardingNSF


NSF refers to a routers ability to almost immediately start forwarding packets following an active processor failure. The FIB (Forwarding Information Base) is initially transferred and actively updated so that when a failure occurs, the router is able to forward packets while the control plane is rebuilt or refreshed


GR-Graceful Restart


IETF specified mechanisms for interaction between routing protocol peers which allow the peer of a failing device to continue forwarding packets to that device, even though the neighbor relationship has been destroyed.


NSR –Non Stop Routing


A routing protocol operating mode where all information needed to fully maintain the neighbor relationship and all its relevant routing information is transferred (or "checkpointed") to the standby processor. No additional communication or interaction with the routing protocol peer is needed in this mode.Some implementations allow the use of both GR and NSR for the same protocol, but single routing protocol session must be either GR or NSR.






BGP NSF Awareness Timers

This section documents the configuration of the BGP graceful restart timers.

(Optional) The restart-time argument determines how long peer routers will wait to delete stale routes before a BGP open message is received. The default value is 120 seconds.

(Optional) The stalepath-time argument determines how long a router will wait before deleting stale routes after an end of record (EOR) message is received from the restarting router. The default value is 360 seconds