Riverbed SteelHead 3070-SD, Руководство пользователя

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74 | Configuring BGP and OSPF Routing Policies on SteelHead SD
Creating routing AS path lists
4. Click the search selector for community list options. In addition to the keywords below, you can also
configure numbers in the range from 1 to 65535 and numbers in AA:NN format where the range for
AA and NN is 1 to 65535.
– internet - Advertises this route to the internet community; by default, all prefixes are members
of the internet community.
– local-AS - Doesn’t advertise the route to any external peers.
– no-export - Instructs routers not to export a prefix to eBGP neighbors. For instance, subnets of
a larger block can be advertised to influence external AS best-path selection, and those not
required for this traffic engineering purpose may be tagged NO-EXPORT to prevent them from
being leaked to the internet (and thus contributing to unnecessary global routing table growth).
– no-advertise - Instructs a BGP router not to advertise the tagged prefix to any other neighbor,
including other iBGP or eBGP routers.
5. Click Submit .
6. To edit a community list, select the list in the Community List page, edit the expressions, and click
Submit .
Figure 8-6. Editing an AS path list
Tip: Click Actions to delete a list.
Creating routing AS path lists
You specify the name of the AS path list and define a regular expression that defines the attributes of the
AS path. For details on how AS path lists are used in BGP path selection, see
“Configuring BGP path
selection” on page 45 .
Important: You must be familiar with creating regular expressions (that is, regex) to create AS path lists. If you are
not familiar with regex, we recommend that you do not configure this feature.
The AS path list can be used while applying route policies at the BGP neighbor level.
To create an AS path list
1. Choose Routing > AS Path List.