[j-nsp] JNCIP questions: eBGP cast study

Yue Min smartsuites at gmail.com
Wed Sep 2 19:10:19 EDT 2009

wow, found a few things I did quite differently than the author does.
anyone interested to discuss? :)

1. "Ensure that all routers in your AS forward through r2 to reach
peer prefixes when r2 is operational."
The author set LP to 101 for AS1492 routes which are recieved by r2
and reflected by RR to r1. I just simply set MED 100 on r2 and MED 200
on r1 and all peering route set LP to 200. quesion: is my solution

2. cust/peer import policy
while the requirement says "Accept all customer routes that have
originated in customer sites to accommodate the C1–C2 EBGP peering
shown earlier in Figure 6.6." ( I feel confued here too. does that
mean R4 should only receive ".* 65010"? but seems the solution in book
allow R4 to receive ".* 65020" too, same on R7 ), but it doesn't say
same thing for peer, so I assume R1/R2 shouldn't use as-path ".* 1492"
as inbound filter as the bood does. any thought on this?

3. export policy
biggest difference is here. what I wrote: ( r4, for example, similar
on other routers )

policy-options policy-statement export-to-cust
term export-internal {
    from {
        route-filter exact accept;
        route-filter exact accept;
        route-filter exact accept;
term export-cust {
    from community [ learned-from-peer learned-from-transit ];
    then accep
term block-all-else {
    then reject;

I just simple use route-filter to select route to announce to peers,
and it doesn't matter the active route in my routing table is IGP
route or BGP route. ( if there're not much internal routes, we use
route-filter, if there're a lot, we use community to select route,
which the active routes have to be bgp route or use advertise-inactive
) however, the book rely on the default bgp policy to announce bgp
route out and then use a route-filter to suppress specific route and
use advertise-inactive to export inactive bgp route due to protocol
preference. my question: is my solution correct?

thanks for anyone interested in discussion. will post more questions
later probabaly...


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