Hi Peter,
Thank you very much.
After it is included in draft-ietf-lsr-dynamic-flooding, we can work
together to reduce the side effect.
Best Regards,
Huaimo
________________________________
From: Peter Psenak <[email protected]>
Sent: Friday, May 24, 2019 5:35 AM
To: Huaimo Chen; Tony Li; [email protected]
Subject: Re: [Lsr] Enhancements on encoding of router IDs and DR IDs
Hi Huaimo,
thanks for the suggestion, I think it's good one to include.
One side effect of your proposal is that when the new ID or DR ID is
inserted, it may cause other IDs/DR IDs to change their index, as you
can not assume you can simply add to the end of the list anymore.
thanks,
Peter
On 23/05/2019 20:47 , Huaimo Chen wrote:
> Hi Tony,
>
>
> Enhancements on encoding the IDs are described below for
> discussions. A .pdf file is attached in the case that the formats below
> are messed up.
>
>
> Currently for OSPFv2, OSPFv2 Area Router IDs TLVs are used to represent
> a sequence of router IDs or DR IDs (addresses). Each of IDs is encoded
> as an OSPFv2 Router IDs TLV Entry of 8 bytes.
>
> 0 1 2 3
>
> 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
>
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
> | Conn Type | Reserved |
>
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
> | Originating Router ID/DR Address (4 bytes) |
>
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
> (Current) OSPFv2 Router IDs TLV Entry
>
>
>
> To represent N router IDs or DR addresses, we need N entries, which
> occupies 8*N bytes in the OSPFv2 Area Router IDs TLVs. Each entry
> represents just only one router ID or DR address.
>
>
>
> An enhancement below is to allow one entry to represent a number of
> router IDs or a number of DR addresses. This can be achieved by using
> two bytes of the Reserved field to indicate the number M of router IDs
> or a number of DR addresses contained in the entry. The value of the
> two bytes can be the number of IDs/Addresses (i.e., M) or the number of
> octets used (i.e., 4*M). The former is preferred.
>
>
>
> 0 1 2 3
>
> 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
>
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
> | Conn Type | NumberOfIDs (M) | Reserved |
>
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
> | 1st Originating Router ID/DR Address (4 bytes) |
>
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
> | 2nd Originating Router ID/DR Address (4 bytes) |
>
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
> | |
>
> ~ . . . . . . ~
>
> | |
>
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
> | M-th Originating Router ID/DR Address (4 bytes) |
>
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
> (Enhanced) OSPFv2 Router IDs TLV Entry
>
>
>
> To represent N router IDs or N DR addresses using the enhanced entry, we
> need just one or a few entries. Using X entries occupies 4*(N + X) bytes
> in the OSPFv2 Area Router IDs TLVs.
>
>
>
> Consider the case where there are 1000 routers in an area. To represent
> 1000 router IDs,
>
> Using the current OSPFv2 Router IDs TLV Entries occupies 8*1000 = 8000
> bytes;
>
> Using the enhanced OSPFv2 Router IDs TLV Entries occupies 4*(1000 + 1) =
> 4004 bytes.
>
> 8000/4004 = 1..998. The saving on space is about 50% in this case.
>
>
>
> Similarly for OSPFv3, OSPFv3 Area Router IDs TLVs are used to represent
> a sequence of router IDs or DR IDs. Each of router IDs is encoded as an
> OSPFv3 Router IDs TLV Entry of 8 bytes. Each of DR IDs is encoded as an
> OSPFv3 Router IDs TLV Entry of 12 bytes.
>
>
>
> 0 1 2 3
>
> 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
>
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
> | Conn Type | Reserved |
>
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
> | Originating Router ID (always present) |
>
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
> | Interface ID (present for DRs) |
>
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
> (Current) OSPFv3 Router IDs TLV Entry
>
>
>
> An enhancement below is to allow one entry to represent a number of
> router IDs or a number of DR IDs. This can be achieved by using two
> bytes of the Reserved field to indicate the number M of router IDs or a
> number of DR IDs contained in the entry. The value of the two bytes can
> be the number of IDs (i.e., M) or the number of octets used (i.e., 4*M
> for M router IDs or 8*M for M DR IDs). The former is preferred.
>
>
>
> 0 1 2 3
>
> 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
>
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
> | Conn Type | NumberOfIDs (M) | Reserved |
>
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
> | 1st Originating Router ID (always present) |
>
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
> | 1st Interface ID (present for DRs) |
>
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
> | 2nd Originating Router ID (always present) |
>
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
> | 2nd Interface ID (present for DRs) |
>
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
> | |
>
> ~ . . . . .. . ~
>
> | |
>
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
> | M-th Originating Router ID (always present) |
>
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
> | M-th Interface ID (present for DRs) |
>
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
> (Enhanced) OSPFv3 Router IDs TLV Entry
>
>
>
>
> Best Regards,
>
> Huaimo
>
>
>
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