update¶

Modify UPDATE message attributes.

Synopsis¶

bgpipe [...] -- update [OPTIONS]

Description¶

The update stage modifies BGP UPDATE messages in-flight. It can rewrite next-hop addresses and manipulate community attributes. Non-UPDATE messages pass through unchanged.

This stage supports bidirectional operation with -LR. Without -LR, it applies only to messages in the stage direction. Combine with --if to apply modifications only to messages matching a filter.

Options¶

Next-hop¶

Option	Type	Default	Description
`--nexthop4`	string		Set next-hop for IPv4 prefixes to this address
`--nexthop6`	string		Set next-hop for IPv6 prefixes to this address
`--nexthop-self`	bool	`false`	Set next-hop to our own IP address (when available)

Communities¶

Option	Type	Default	Description
`--add-com`	string		Add a standard BGP community (`ASN:value`)
`--add-com-ext`	string		Add an extended BGP community (JSON, see below)
`--add-com-large`	string		Add a large BGP community (`G:L1:L2`)
`--drop-com`	bool	`false`	Remove the COMMUNITY attribute entirely
`--drop-com-ext`	bool	`false`	Remove the EXT_COMMUNITY attribute entirely
`--drop-com-large`	bool	`false`	Remove the LARGE_COMMUNITY attribute entirely

Unlike its siblings, --add-com-ext takes the JSON object format used in the EXT_COMMUNITY attribute output, e.g. '{"type": "TARGET", "value": "65000:100"}' (or a JSON array of such objects).

For each attribute, drop takes precedence: when both --drop-com* and the matching --add-com* are given, the attribute is dropped and the add is ignored.

Messages without reachable prefixes (pure withdrawals) are passed through unmodified: per RFC 4271 section 4.3, a withdrawal must not carry path attributes.

Examples¶

Rewrite next-hop for all updates:

bgpipe \
    -- connect 192.0.2.1 \
    -- update --nexthop4 10.0.0.1 \
    -- connect 10.0.0.1

Add a community to tag traffic from a specific peer:

bgpipe \
    -- connect 192.0.2.1 \
    -- update --add-com 65000:100 \
    -- connect 10.0.0.1

Strip all communities before forwarding:

bgpipe \
    -- connect 192.0.2.1 \
    -- update --drop-com --drop-com-ext --drop-com-large \
    -- connect 10.0.0.1

Conditionally modify: add a community only to RPKI-invalid updates:

bgpipe \
    -- connect 192.0.2.1 \
    -- rov --invalid keep \
    -- update --if 'tag[rov/status] == INVALID' --add-com 65000:666 \
    -- connect 10.0.0.1

Set next-hop to self (useful when proxying):

bgpipe \
    -- listen :179 \
    -- update --nexthop-self \
    -- connect 192.0.2.1