# Revision history [back]

You assume that the AS's in a path segment are being processed as a set. But what you ask for is the 'as4', or in your later example 'as2' fields (bgp.update.path_attribute.as_path_segment.as2) . When you look at the packet in detail you'll see that each AS4, and AS2, field is added individually to the tree; each is handled individually and therefore shown as such. At that field level there is no notion of groups or sets.

One level up though is where the the grouping comes into view. The AS Path Segment item in the tree nicely shows the collection of AS's in that path segment. So it would be nice if we could use bgp.update.path_attribute.as_path_segment. Unfortunately this item is of type FT_NONE, thus has no value. It is merely a hook to append text to. If you use that as a field to output you'll only be informed of the presence of the item, by means of a 1 in the output.

What seems to be lacking here is assigning some value (a string from the looks of it) to this tree item, so that it can be used as such, producing useable output when used as a field in the output. So in short, no this is currently not possible. I'm not even sure that is possible at all. It would be an enhancement to be looked into.

You assume that the AS's in a path segment are being processed as a set. But what you ask for is the 'as4', or in your later example 'as2' fields (bgp.update.path_attribute.as_path_segment.as2) . When you look at the packet in detail you'll see that each AS4, and AS2, field is added individually to the tree; each is handled individually and therefore shown as such. At that field level there is no notion of groups or sets.

One level up though is where the the grouping comes into view. The AS Path Segment item in the tree nicely shows the collection of AS's in that path segment. So it would be nice if we could use bgp.update.path_attribute.as_path_segment. Unfortunately this item is of type FT_NONE, thus has no value. It is merely a hook to append text to. If you use that as a field to output you'll only be informed of the presence of the item, by means of a 1 in the output.

What seems to be lacking here is assigning some value (a string from the looks of it) to this tree item, so that it can be used as such, producing useable output when used as a field in the output. So in short, no this is currently not possible. I'm not even sure that it is possible at all. It would be an enhancement of the BGP dissector to be looked into.