North American Network Operators Group

Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical

Re: IS-IS reference

  • From: Alex P. Rudnev
  • Date: Wed Sep 15 14:03:21 1999

First of all. I should apologize for this thread - seems it is one more 
grinding of the well-known things. And I never opposed to you.

Second, it seems for me there is really a lack of the good books about 
the INTERNET and it's routing. The book mentioned below (btw, the 
author's name at the paper book is Bassam Halabi, and differ slightly 
from the one at the CCO server) describe BGP brightly, but do not explain 
HOW TO DESIGN SIMPLE single-homed customer's network; multi-homed 
customer's network; non-transit ISP; transit ISP...

And then (It's more the request to those who write the books) there is a 
lack of the books explaining _what for this protocol was designed_ and 
_how to use it in the 90%  cases_. Good example #1 - OSPF - all books 
describe AREAS, STUB's, DEAD INTERVAL, etc etc - but the first idea of 
OSPF was _to be very simple in the simple cases_. It causes the students 
(I had a time to watch their attempts to do simple labs here) to write a 
complex, 100 lines-at-the-size configs from the first minute they began 
to type in something into the router, or write terrible _redistribute_, 
_stub_ etc when this configs are not necessary at all. This resulted to 
the myths about the _complexity_ or _unstability_ or _difficulty to 
config_ etc etc...

BGP - the same problem. Halabi write the excellent book; but try to 
configure the simple _multi-homed_ customer's network guided by this 
tool? First of all, no one word about IGP backgrounding network; second, 
no distinction between the _SIMPLE_ cases (when it's better to write

 router bgp 1111
 neig remote-as 1112
 ip route Null0 254

and the complex cases when you should transit third-party BGP routes by 
your multi-area backbones. 

And it's amazing - we are talking (this days) about L2/L3 switching, 
about MPLS, tagging etc etc - and we just have almost ready 2-level 
network (IGP - IBGP), but withouth any attempting to use any packet 
tagging. Think - edge router receive the packet, and find the appropriate 
route in BGP table; this route reference to the BGP next hop (outgoing 
edge router). Instead of the tagging this packet by this _NEXT HOP_ 
address (and marking it's CoQ and other attributes) it send it unchanged 
to the next core router and the whole indentification repeats again... 
and again... And then some folks cry _we can use ATM background instead 
of IGP background_ and draw MPLS heap of comlexity...

Btw, if summ everything was saying here in nanog by this Sublect, we 
could collect a good FAQ by this subject _how to build simple ISP 
backbone_ -:).

Aleksei Roudnev, Network Operations Center, Relcom, Moscow
(+7 095) 194-19-95 (Network Operations Center Hot Line),(+7 095) 230-41-41, N 13729 (pager)
(+7 095) 196-72-12 (Support), (+7 095) 194-33-28 (Fax)