Below you'll find a list of all posts that have been tagged as “BGP”
AS-PATH prepending stand for announce my prefix with a low priority. This technique, in a multihomed BGP scenario, it is used to lighten the traffic coming from a peer. The BGP route selection process prefer prefix with a short AS-PATH instead a long AS-PATH. FIRST create an ACL to select your source prefix the traffic to prepend: SECOND create a …
Have you ever received many networks from your customers without being able to summarize with an IGP? And… have you ever had to make BGP transit for these messy networks to a carrier that accepts only /20 networks or even worse check on RIPE.NET database? Little trick with aggregate command: Warning: aggregate command not work if you advertize messy networks …
as Internet Service Provider you must ensure that packets are passing your network reach the destination as quickly as possible and with the least number of hops. To do this you should exchange your networks with others: Peering. Mosts internet peerings in the world is maded by Handshake Agreement. Here you can find a draft with all important information to …
Yesterday, 20190624, a routes leak hit majors Internet player like Cloudflare, Verizon and Amazon AWS that were obfuscated by a network outage. An impressive recon and report were made by CloudFlare that early detect the problem and helped AS33154 to solve the problem. You can find the complete report here. But what happened? Briefly, it seems that a BGP protocol …
by default a BGP session do not shutdown until the Hold timer times out. In Huawei Keep-alive is 60s and Hold-time is 180s. So if we are in multi ISP environment and internet peer go down, the networks preferred by the failed peer are black-holed. With the command: ebgp-interface-sensitive The BGP router clear the peer session immediately if the interface …
Routing table represent all the information the bgp protocol collect from his peers to build the IP Routing table. On these examples you can find small details that are useful for troubleshooting. Of course every time you type the display bgp routing-table command you have a little codes legend: But dig a little bit: Status codes are the very firsts …
Protecting the internal network or a public network segments is the Network Engineer mission’s. Usually, we have firewalls for the perimetral security, but how do we do if we want to protect public transit IP? Some public IP addresses configured on Customer Edge Routers, provide only the traffic routing from the client side to the ISP so there is no …