MPLS CHAPTER 7

MPLS CHAPTER 7
QUESTIONS :
23. What command is used to enter the "VPNv4 Section" of BGP ?
24. What is use of Extended Community ?
25. Why would you activate VPNv4 capability with an iBGP peer ?
26. What are to commands to activate VPNv4 feature ?
Solution:

23. What command is used to enter the "VPNv4 Section" of BGP ?
24. What is use of Extended Community ?

- VPNv4 Route
. RD + Prefix makes VPN routes globally unique
- MPLS VPN label
. PE routers exchange label for each customer route via VPNv4
- Transport Label
. Label towards PE's BGP next-hop

VPNv4 bgp has two jobs to get the label information , remote label
information.

payload information:

|transport lable|vpn label|IP | TCP | WWW |
(which PE)       (which cust)
 
Route distinguiser (RD)

- ASN:nn or IP-addres:nn
  vrf rd are locally significant to give them globally significance
  we are using route-targets.
 
  VPNv4 Route Target:
. 8 byte field per RFC 4360 "BGP Extended Communities Attribute"
. Format Similar to route distinguisher
- ASN:nn or IP-addres:nn
. VPNv4 speakers only accept VPNv4 routes with a route-target matching
  a local VRF
  - Route reflection exception
  - no bgp default route-target filter
 
  Controlling VPNv4 Routes:
. Route distinguisher used solely to make route unique
. New BGP extended Community "route-target" used to control
  what enters/exits VRF table
. "export" route-target  vrf ----> bgp
. "import" vrf <----- bgp
. Allows granular control over what sites have what routes
- import map & export map allow control on a per prefix basis

26. What are to commands to activate VPNv4 feature ?

In diagram let us enable VPNv4 on both PE's

dia:

on PE-R1
PE0R1#sh run | se bgp
router bgp 100
 no synchronization
 bgp log-neighbor-changes
 neighbor 3.3.3.3 remote-as 100
 neighbor 3.3.3.3 update-source Loopback1
 no auto-summary
 !
 address-family vpnv4
  neighbor 3.3.3.3 activate
  neighbor 3.3.3.3 send-community extended
 exit-address-family

 on PE-R3
 PE0R3#sh run | se bgp
router bgp 100
 no synchronization
 bgp log-neighbor-changes
 neighbor 1.1.1.1 remote-as 100
 neighbor 1.1.1.1 update-source Loopback1
 no auto-summary
 !
 address-family vpnv4
  neighbor 1.1.1.1 activate
  neighbor 1.1.1.1 send-community extended
 exit-address-family

some more verification commands:

PE0R1#sh ip bgp neighbors | se capabilities
  Neighbor capabilities:
    Route refresh: advertised and received(old & new)
    Address family IPv4 Unicast: advertised and received
    Address family VPNv4 Unicast: advertised and received

# sh control-plan host open-ports