[nsp] BGP Advertisements

From: Vinod Anthony Joseph Cherunni (vac@antarix.net)
Date: Sat Feb 03 2001 - 02:12:42 EST


Dear All,

Once again some queries in my mind. Out of a /18 address block that has
been allocated to me, which I am further subnetting to achieve multiple
/30 prefixes to allocate addresses for all my links. The following queries
arise in my mind.

(a) How would I announce those /30 prefixes to an upstream provider. I
mean that If I am using the following /24 block "202.9.4.0/24" to break it
into multiple /30 prefixes which would effectively give me 64 of such
prefixes, & assuming only two /30 prefixes are put into use.. This means
that only two /30 prefixes will be in my IGP routing table. Now how will I
aggregate these multiple /30 prefixes into a single probably /24 block &
announce it

If I have currently only allocated 202.9.4.4/30 & 202.9.4.8/30 for two
links & the remaining /30 prefixes are unused. Can I summarize them as
follows in BGP

router bgp 1076
no auto-summary
no synchronization
neighbor a.b.c.d remote-as x
aggregate-address 202.9.4.0 255.255.255.0 summary-only (Is this okay or else will I have to list the two /30's using "network"
statements. Feel it won't scale since the number will grow large.)

(b) Also I am starting off with using private addresses at small portions
of my internal network due to some reasons, & use NAT for translating an
internal private IP Prefix to a valid IP /24 prefix. How could I announce
it to an external peer. Because I would'nt have any entry in the internal
routing table for the NAT public prefix.

(c) Lastly is it advicable to announce the entire /18 allocated to me
using an ip route to null for the entire /18 even though its not being
fully utilized, if I would need to do that.

Kindly enlighten me.

With warm regards,

Vinod.



This archive was generated by hypermail 2b29 : Sun Aug 04 2002 - 04:12:27 EDT