BGP Path Selection Juniper vs. Cisco vs. HP/Huawei

This is just a sort summary sheet about how the BGP path selection process is done by different vendors:

Cisco Juniper HP and Huawei
1 Path with highest WEIGHT Path with highest WEIGHT (PreVal)
2 Path with highest LOCAL_PREF Path with highest LOCAL_PREF Path with highest LOCAL_PREF
3 Lowest AIGP attribute
4 Path originated by the local router Path originated by the local router
5 Path with shortest AS_PATH Path with shortest AS_PATH Path with shortest AS_PATH
6 Path with lowest origin code Path with lowest origin code Path with lowest origin code
7 Path with lowest MED Path with lowest MED Path with lowest MED
8 Striclty prefer internal paths
8 Prefer eBGP over iBGP paths Strictly prefer external BGP paths Prefer eBGP over iBGP paths
9 Path with lowest IGP metric to the BGP next hop Path with lowest IGP metric to the BGP next hop Path with lowest IGP metric to the BGP next hop.
10 Determine if BGP multipath is needed Prefer the path with maximum IGP next hops
11 eBGP Path that was received first eBGP Path that is currently active
12 Prefer the path with lowest router ID Prefer the path with lowest router ID
13 Path with shortest CLUSTER_LIST Path with shortest CLUSTER_LIST Path with shortest CLUSTER_LIST
14 Path with smallest ORIGINATOR_ID
15 Prefer the path with lowest router ID
16 Path that comes from the lowest IP address Prefer the path with lowest peer IP address Path that comes from the lowest IP address

Book list for JNCIE-SEC

Must read!

I would suggest the following books for your preparation towards JNCIE-SEC.

Free available:

Must buy:

What else?

I didn’t read any workbook from iNET Zero/Proteus or Twine, so I can’t suggest them. But maybe you have some experience with them and leave comment!  Do you know more good sources of informations for JNCIE-SEC?

Ping to multiple IPs permanently with RPM

In your exam you should always check the connectivity to all your devices, after configuration changes. Just to make sure everything working as expected. You can use RPM Services to send continually pings to the routers in your network. If the ping fails you can check it by an operational mode command or see it in your /var/log/messages.

Example configuration:

services {
    rpm {
        probe R1 {
            test ping-R1 {
                probe-type icmp-ping;
                target address 10.0.1.1;
                test-interval 30;
                thresholds {
                    successive-loss 1;
                }
            }
        }
        probe R2 {
            test ping-R2 {
                probe-type icmp-ping;
                target address 10.0.1.2;
                test-interval 30;
                thresholds { 
                    successive-loss 1;
                }
            }
        }
    }
}

Now your router send every 30 seconds (test-interval) a icmp request (probe-type) to your destinations (target address).

To monitor the operation and even see failures you can use the following commands:

  • show services rpm history-results
  • show services rpm probe-results
  • look in /var/log/messages for PING_TEST_FAILED

 

 

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