Subject: RE: [Isis-wg] doubts on IS-IS topology and addressing

From: Jeff Parker <[email-masked]>
Date: Fri, 10 Aug 2001 15:04:59 -0400

> 1. Is it must for Level-1 IS to have a adjacency maintained 
> with a Level-2 IS or can the Level-1 IS communicate with a 
> Level-2 IS via Level-1 IS?

No, yes.  In the figure below, IS A can communicate with IS C via IS B.

	L1 A ====== L1/2 B ==== L2 C

> 2.Regarding the ISO DCC addressing format adopted for Is-IS 
> addresses using semi-octet decimal digits representation, the 
> DSP is allocated 0-35 digits. Assuming CFI =1 (single digit), 
> then CDI = 3digits,ESI = 31 digits, which adds up the total 
> digits in the DSP to 35 digits. How is SEL field of the DSP 
> accomodated in this case?
>
> Manigandan

There is a great deal of structure embedded in the ISO area
field.  However, the good news is that routers that don't need
to route OSI traffic don't need to pay attention to this, and
can treat the addresses as opaque tokens.  Likewise, an OSPF 
area is formated like IP addresses, but is not interpreted as such.

- jeff parker
- axiowave networks
_______________________________________________
Isis-wg mailing list  -  [email-masked]
http://external.juniper.net/mailman/listinfo/isis-wg