Category Archives: Uncategorized

Arista – dealing with inactive routes in BGP

In EOS, BGP implementation normally considers only active routes in RIB for advertisement to its peers. In certain deployments, IGP protocol like OSPF may carry same set of prefixes as BGP (especially if we use OSPF to form iBGP). In addition, routes from OSPF and BGP may be mutually redistributed. As a result, when local… Read More »

Arista EOS – BGP remove-private-as

This is a post copied/stolen/updated from Kevin Wang’s wiznote – [EOS] [RFC6996] BGP remove-private-as.  Summary: Feature support starts from 4.19.1F and 4.18.4F “remove-private-as” works for both 2B/4B AS#.  Private AS number: 64512-65534(2B), 4200000000-4294967294(4B). convert to asdot notation is 64086.59904. “neighbor x.x.x.x remove-private-as” only works for those as-path which only have private as number present. 3. In… Read More »

BGP as-path regular expressions

A regular expression is the character pattern that can be matched against an input string. Regular expressions can be built using letters (A through Z, a through z), numbers (0 through 9) and other keyboard characters, such as the exclamation point (!) or a tilde (~). A regular expression can be a single-character pattern or… Read More »

BGP Additional Paths

BGP routers only advertise the best path to their neighbors. When a better path is found, it replaces the current path. Advertising a path and replacing it with a new path is called an implicit withdraw. Since we only advertise the best path, a lot of other possible paths are unknown to some of the… Read More »

VPN Ports

  PPTP:To allow PPTP tunnel maintenance traffic, open TCP 1723.To allow PPTP tunneled data to pass through router, open Protocol ID 47. L2TP over IPSecTo allow Internet Key Exchange (IKE), open UDP 500.To allow IPSec Network Address Translation (NAT-T) open UDP 4500.To allow L2TP traffic, open UDP 1701. OpenVPN: OpenVPN uses port 1194 udp and… Read More »